 Section 22 of the Science History of the Universe, Volume 6. This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer, please visit LibriVox.org. Recording by Melanie Young. The Science History of the Universe, Volume 6. Edited by Francis Roteweeler. Botany, Taxonomic Botany, Part 1. The first great division of the plant kingdom comprises the algae and fungi, grouped under the term thalophytes, meaning plants wherein such special vegetative organs as leaves and roots are either lacking or rudimentary. The algae grow in the water and hence their habits are adapted to a water environment. They are often called seaweeds, but although they are very abundant along sea coast, they are also found in fresh waters. Some of them are so small that the individual bodies are visible only under the microscope, but others are large, the sea kelp having been known to have a stem 900 feet long. Although all algae contain chlorophyll, and hence are able to make their own food, they do not all appear green. For in many of them the chlorophyll is obscured by other coloring matters. The four great groups of algae are named from the general color of their bodies. The blue-green algae, or the green slimes, form blue-green or olive-green patches on damp tree trunks, rocks, and walls. The name of the group refers to the fact that in addition to the chlorophyll, the cells contain a characteristic blue coloring matter, which does not mask the green, but combined with it, gives a bluish-green tint to the plants when seen in masses. Not all the blue-green algae are bluish-green in tint, however, for the presence of other substances may disguise it, and the color may be yellow or brown or even reddish. The color of the red sea, which has given it its name, is due to the presence under certain conditions of immense quantities of one of the blue-green forms. The green algae are so named because the green of the chloroplasts is neither modified nor obscured by other colors, and the plants have a characteristic grass-green color. Some of the green algae are associated with the blue-green algae in the pollution of water reservoirs. The brown algae, of which the giant kelp of the Pacific coast, with a length of 900 feet is the largest, are all anchored plants, chiefly marine. The first great group of brown algae, of which a small form, ectocarpus, is a well-known representative, is distinguished by its swimming spores and its similar gametes. The smaller group, besides the common rockweed, or cucas, contains the famous gulfweed, or sargassoweed, which makes a floating bank of dense weed in the North Atlantic, known as the sargasso-sea. These differ from the first group in producing no swimming spores, and in its dissimilar gametes, eggs and sperms. The red algae are mostly marine forms and receive their name from the fact that a red-coloring matter completely masks the chlorophyll. As a consequence, the plants are various shades of red, violet, dark purple, and reddish brown, often beautifully tinted. In general, the bodies are much more graceful and delicate than those of the brown algae. There is the greatest variety of forms, branching filaments, ribbons, and filmy plates, prevailing, and often profuse branching occurs, the plants resembling mosses of delicate texture. The reproduction of the red algae is very peculiar, being entirely unlike that of the other algae. No swimming spores are produced, but sporangia occur that produce and discharge spores without the ability to swim. Since each sporangium usually produces four such spores, they are called tetraspores. Floating about in the water instead of actively swimming, they finally germinate and produce new plants. The sexual reproduction, however, is most remarkable. The sperms, like the tetraspores, are without cilia and simply float into contact with the carpagonium, whose form is like that of a flask with a long, narrow neck. In the bulbous base of the carpagonium, the female cell is developed. In a very simple case, the floating sperm comes in contact with the long neck. The two walls become perforated at the point of contact. The contents of the sperm enters and passes to the carpagenic cell, and thus fertilization is accomplished. As a result of fertilization, there appears on the plant a spore-containing structure, like a little fruit. The spores it contains produce the algae plants again. The fungi do not contain chlorophyll, and this fact forms the sharpest contrast between them and the algae. The presence of chlorophyll enables the algae to be independent of any other organism, since they can manufacture food out of carbon dioxide and water. The absence of chlorophyll compels the fungi to be dependent upon other organisms for their food. This food is obtained in two general ways. Either one, directly from living plants and animals, or two from organic waste products or dead bodies. In case a living body is attacked, the attacking fungus is called a parasite, and the plant or animal attacked, the host. In case the food is obtained in the other way, the fungus is called a saprophite. For example, the rust that attacks wheat is a parasite, and the wheat is the host. While the mold, which often develops on stale bread, is a saprophite. Bacteria include the smallest known living forms of fungi, some of which are spherical cells, only one 25,000 of an inch in diameter. It is estimated that 1,500 of certain rod-shaped forms placed end to end would about stretch across the head of an ordinary pen. Even to distinguish ordinary bacteria, therefore, the highest powers of the microscope are necessary. However, they are so very important to man, on account of their useful and destructive operations, that every student should have some information about them. Public attention has been drawn to them chiefly on account of the part they play in many infectious diseases. Bacteria are found almost everywhere, in the air, in the water, in the soil, in most foods, and in the bodies of plants and animals, as regular inhabitants. Many of them are entirely harmless, some are useful, and others are very dangerous. The pure water of springs and wells contains abundant bacteria. While in stagnant water and sewer water, they swarm in immense numbers. Reproduction is by cell division, as among the blue-green algae, a group which the bacteria resemble in many ways. This cell division is remarkably rapid in bacteria, resulting in such prodigious multiplication of individuals in a comparatively short time that it is impossible to imagine what would happen if bacteria were left free to reproduce to their full capacity. Bacteria have been observed to reproduce themselves in 15 to 40 minutes after their formation. That is, a single generation of such bacteria is that length of time. It would be interesting to determine the number of progeny from a single bacterium at the end of 24 hours if such a rate were maintained. Yeast are much larger than bacteria and have a more complex cell structure, for there is present a clearly defined nucleus. These cells reproduce in a peculiar method called budding. This consists in a cell putting out one or more projections, which gradually enlarge and finally become pinched off. Often the cells thus produced cling together in short irregular chains. The chief interest in connection with yeast is the important part they play in the fermentation of sugar solutions. Splitting the sugar into alcohol and carbon dioxide, a process also induced by certain bacteria, but chiefly by the yeast. Fermentation by yeast is employed on a large scale in the manufacture of beer, wine, and spirits, and in the making of bread. In the last named process, the dough is inoculated with yeast plants and placed in a sufficiently warm temperature to induce rapid growth. The plants begin to reproduce actively by budding. The sugar in the dough is split into alcohol and carbon dioxide, and the latter, a gas, expands and puffs up the dough, making it light and porous, that is causing it to rise. One of the most common of the mucors, or bread molds, forms white furry growths on damp bread, preserved fruits, manure heaps, etc. It may be grown easily by keeping a piece of moist bread in a warm room under a glass vessel. The sources of its food supply indicate that it is a saprified. Rust are destructive parasites that attack almost all seed plants, but those that attack the cereals are of special importance. Wheat, oats, rye, and barley all have their rusts, and in the United States there is a yearly loss of several million dollars on account of the ravages of the wheat rust alone, scarcely a field being entirely free from the pest. Naturally these parasites have been investigated persistently, but while very much has been learned about their life histories and behavior, no remedy has been discovered. It has been found that certain varieties of wheat resist the rust better than others, and that varieties ripening early escape serious injury, and these facts may lead to the breeding of resistant and early races. The popular idea of a fungus is that of a fleshy, colorless form, such as the mushroom. This name is very indefinite being sometimes applied to any of the fleshy fungi of the umbrella form, and sometimes including among such forms only those that are edible, the poisonous forms being spoken of as toadstools. The life history of the ordinary edible mushroom of the markets will serve as an illustration. The mycelium of white branching threads spreads extensively through the substratum of decaying organic material, and by those who grow mushrooms is called spawn. This mycelium, although the least conspicuous part of the mushroom is, of course, the real vegetable body. Upon this underground mycelium little knob-like protuberances arise, or buttons, growing larger and larger until they develop into the umbrella-like structures commonly spoken of as mushrooms. This umbrella-like structure, however, corresponds to the sporophores that arise from the mycelia of other groups of fungi, except that it includes a large number of sporophores organized into a single large body. Therefore, the real mushroom body is a subterranean mycelium, upon which the structures commonly called mushrooms are the spore-bearing branches. In pulling up a mushroom, fragments of the mycelium may often be seen attached to it looking like small rootlets. The puffballs are fleshy fungi that differ from the mushrooms, and having the spores enclosed until they are ripe. There is a subterranean mycelium, as in the mushrooms, but the spore-bearing structure is a fleshy globular body containing irregular chambers lined with the spore-producing layer. When young, this body is solid and white, but as the spores mature, it becomes yellowish and brownish, gradually dries up. And finally is only a brown parchment-like shell containing innumerable exceedingly small spores that are discharged by the breaking of the shell. Some of the puffballs become very large, reaching a diameter of 12 to 18 inches. Likens are abundant everywhere, forming splotches of various colors on tree trunks, rocks, old boards, etc. They have a general greenish-gray color, but brighter colors also may be observed. The great interest connected with likens is that they are not single plants, but that each lichen is formed of a fungus and an algae, living together so intimately as to appear like a single plant. In other words, a lichen is not an individual, but a firm of two individuals vary unlike one another. If a lichen be sectioned, the relation between the two constituent plants may be seen. The fungus makes the bulk of the body with its interwoven mycelial threads and the meshes of which lie the algae, sometimes masked. It is these enmeshed algae showing through the transparent mycelium that give the greenish tint to the lichen. It has been found that the lichen algae can live quite independently of the lichen fungus. On the other hand, it has been found that the lichen fungus is completely dependent upon the algae. For the germinating spores of the fungus do not develop far unless the young mycelium can lay hold of suitable algae. Artificial likens also have been made by bringing together wild algae and lichen fungi. Likens, therefore, are really combinations of a parasitic fungus and its host, the parasitism being peculiar in that the host is not injured. The fungus lives upon the food made by the algae and the relation suggested is that the algae is enslaved by the fungus. With the liverworts, a new division of the plant kingdom is entered, known as the bryophytes, possessing archegonia, but no vascular system. Among these, the simplest of the archegonia forms are found. Mosses are very abundant and familiar plants. They grow in all conditions of moisture. Many of them can endure drying out wonderfully, and hence they can grow in very much exposed situations, as do many lichens. In fact, lichens and mosses, being able to grow in the most exposed situations, are the first plants to appear upon bare rocks and ground, and are the last plants seen in climbing high mountains or in going to very high latitudes. Mosses have great power of vegetative multiplication, new leafy branches putting out from old ones indefinitely, thus forming thick carpets and masses. Bog mosses often completely fill up bogs or small ponds and lakes with a dense growth, which dries below and continues to grow above, so long as the conditions are favorable. These quaking bogs or mosses, as they are sometimes called, furnish very treacherous footing and less rendered firmer by other plants. The conspicuous part of an ordinary moss plant consists of a more or less erect and usually branching stem bearing numerous delegate leaves. The plant is evidently able to make its own food and it is anchored to its substratum by hair-like rhizoids. Its power of vegetative propagation has been described. At certain times there appears at the end of the main stem or at the end of a branch a rosette of leaves, often called the moss flower. In the center of this rosette there is a group of antheredia and archegonia, sometimes both kinds of organs and a single rosette, sometimes only one kind. From the fertilized egg cell of the archegonium arises the capsule containing spores or sporophyte from which the new moss plant springs. End of Section 22 Recording by Melanie Young Section 23 of the Science History of the Universe This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer, please visit LibriVox.org. Recording by Melanie Young The Science History of the Universe Volume 6 edited by Francis Rowe Wheeler. Botany Taxonomic Botany Part 2 The Third Division, or Turidophytes is represented first by the ferns, but also includes the horsetails and club mosses. The ferns are well-known plants and the ordinary forms are easily recognized. In fact, the general appearance of the large compound leaves is so characteristic that when a leaf is said to be fern-like, a particular appearance is suggested. In the tropics not only are great masses of the low forms to be seen from those with delicate and filmy moss-like leaves to those with huge leaves, but also tree forms with cylindrical trunks encased by the rough remnants of fallen leaves and sometimes rising to a height of 35 to 45 feet with a crown of great leaves 15 to 20 feet long. If an ordinary fern be examined it will be discovered that it has a horizontal underground stem or rootstock, which sends out roots into the soil and one or more large leaves into the air. These leaves, appearing to come directly from the soil, were once supposed to be different from ordinary leaves and were called fronds. But although the name is still used in connection with fern leaves, it is neither necessary nor accurate. These leaves are usually compound, branching either penately or palmately. There are two peculiarities about fern leaves that should be noted. One is that in expanding the leaves seem to unroll from the base as though they had been rolled from the apex downward, the apex being in the center of the roll. When unrolling this gives the leaves a crossier-like tip. The other peculiarity is that the veins fork repeatedly. This combination of unrolling leaves and forking veins is very characteristic of ferns. Probably the most important fact about the fern body, says Coulter, is that it contains a vascular system. The appearance of this system marks some such epoch in the evolution of the plants as is marked among animals with the appearance of the backbone. As animals are often grouped as vertebrates and invertebrates, so plants are often grouped as vascular plants and non-vascular plants. The latter being the thalophytes and the brioophytes, the former the ferns and the seed plants. The presence of this vascular system means a special conducting system and in connection with it the most roots and the first complex leaves. On account of the vascular system and other resistant structures the remains of ferns have been preserved in great abundance in the rocks. These records show that the ferns are a very ancient group occurring in special abundance during the coal measures. Another striking fact about this leafy body of the ferns is that it never produces ferns but does produce spores abundantly. This means that it is the sporophyte in the life history of the fern and when it is contrasted with the sporophyte of brioophytes the differences are remarkable. Among the liverworts and the mosses the sporophyte is a leafless structure attached to the gametophyte and dependent on it while the gametophyte is the leafy body of all work. Among the ferns however the sporophyte is an elaborate leafy structure and entirely independent. Therefore when one ordinarily speaks of a moss and a fern the gametophyte is referred to in the former case and the sporophyte in the latter. This means that in passing from mosses to ferns plants have transferred the chief work of food manufacturer from the gametophyte to the sporophyte which has thus become the conspicuous generation. The sharp and easily marked distinction between the profilus or gametophyte and the fern plant itself sporophyte has led certain writers on biology to consider the fern as a typical plant for the purpose of comparison with certain typical animals which are assumed to represent a similar stage of evolutionary development. Aside from the dangers which arise of fern it must be said that in many respects ferns are not typical. They should not be regarded as the ancestors of the present flowering plants. But as a somewhat highly specialized offshoot from the main line of descent which at the present geological age is not biologically successful in competition with the seed bearing forms. The gymnosperms are one of the two groups of seed plants. The most familiar ones in temperate regions being pines, spruces, hemlots, cedars, etc. the group commonly called evergreens. It is an ancient group for its representatives were associated with the giant club mosses and horsetails in the forest vegetation of the coal measures. Only about 400 species exist today as a remnant of its former display. Although it still forms extensive forest. Gymnosperms are very diverse in habit. They are all woody forms but they may be gigantic trees trailing or straggling shrubs or high climbing vines. There are two prominent living groups of gymnosperms. Psycads are tropical forms with large fern-like leaves. These stem is either a columnar shaft crowned with a rosette of large compound leaves with the general habit of tree ferns and palms. Or they are like great tubers crowned in the same way. The tuberous stems are often more or less buried. In ancient times psycads were very abundant but now they are represented by about 80 species scattered through the oriental and occidental tropics. They are especially interesting in their resemblances to ferns and some of them might be mistaken for ferns did they not bear large seeds. Conifers are the common gymnosperms often forming great forests in temperate regions. Some of the forms are widely distributed as the pines while some are now very much restricted as the gigantic redwoods or sequoia of the pacific slope. The habit of the body is quite characteristic of the central shaft extending to the very top. In many cases the branches spread horizontally with diminishing length at the top forming a conical outline as in the ferns. This habit gives the conifers an appearance very distinct from that of the other trees. The large cone of the pine is made up of sporefills that become very thick and hard and that are packed closely together to let out the seeds. On the upper side of each sporefill near its base there are two sporangia in each one of which there is a single large spore or megaspore. So large is the spore that it looks like a conspicuous cavity in the center of the sporangium. These structures also bear old names that may be used. The sporangia were called ovules and the sporefill bearing them was called a carpal. The large spore was regarded only as a cavity in the ovule. The cone therefore is a group of carpals and to distinguish it from the staminate cone it may be called the carpalate cone. It is evident that the pine tree bearing the sporangia is the sporefite in the life history. That is it is the sexless generation. The sporefite has now become so prominent that it seems to have become the whole plant. The pine being hetero sporus there are male and female gametophytes. The small spores or pollen grains germinate and produce very small male gametophytes. Only a few cells are formed and these remain in the pollen grain. The single large spore within the ovule is peculiar in never leaving it. It is never shed but produces a female gametophyte which lies embedded in the center of the ovule. The reason therefore why the gametophytes of such plants are not ordinarily seen is that one is within the pollen grain and the other within the ovule. Before fertilization can take place remarks Coulter, the pollen grain which develops the male gametophyte with its sperms must be brought to the ovule since the female gametophyte with its archegonia. The pollen grains or microspores are formed in very great abundance, are dry and powdery and are scattered far and wide by the wind. In the pines and their allies the pollen grains are winged so they are well organized for wind distribution. So abundant is the pollen of conifers that it sometimes falls like a yellow shower and the occasionally reported showers of sulfur are really showers of pollen from some forest of conifers. Some pollen must reach the ovules and to ensure this it must fall like rain. To aid in catching the falling pollen the scale-like carpals of the cones spread apart and the pollen grains sliding down their sloping surfaces collect in a little drift at the bottom of each carpal where the ovules are found. In this position each of the most favorably placed pollen grains begins to put forth a tube a pollen tube. This tube containing the two sperms in its tip grows through the ovule and reaches the archegonia. Then the sperms are discharged and when they reach the egg fusion takes place and fertilization is accomplished. The angiosperms are the flowering plants. In many flowers there is no regularity in the number of members in each set. For example in the water lily petals and stamens occur in indefinite numbers and in the buttercup the same is true of stamens and carpals. In most flowers however definite numbers appear either in some of the sets or in all of them. When these definite numbers are present they are prevailing either three or five that is there are either three or five sepals, petals, stamens and carpals although it is very common to have two sets of stamens in which case they number six or ten. These numbers appear so constantly in great groups that the two grand divisions of angiosperms called monocotyledons and dicotyledons are characterized by them the former having the parts the flower in threes the latter in fives. This does not mean that all flowers of these two divisions have one or the other number but that these are the prevailing numbers in case there is a definite number at all. Not a few dicotyledons have flowers with the parts in threes and a still larger number have them in fours. In many cases stamens and pistols are not found together in the same flower. In such cases there are stamina flowers that is those without pistols and pistolet flowers that is those without stamens. These two kinds of flowers may be born upon the same plant which is then said to be monetius or one household or upon different plants which are then said to be dicetius or two households. These terms are applied indifferently to the plants or to the flowers either the plants or the flowers being spoken of as monetius or dicetius. About 40 monocotyledonus families are recognized containing numerous genera and about 20,000 species. The dicotyledons are a much larger group than the monocotyledons containing more than 200 families and about 100,000 species. Most of them are easily recognized by the floral number 5 or 4, the net veined leaves and the arrangement of the vascular bundles of the stem and a hollow cylinder. In the lower stretches of the dicotyledons there are a number of small families that include the most common hardwood or deciduous trees and this assemblage of conspicuous forms may be considered together without selecting any special family. They include elms, sycamore, walnuts, hickories, oaks, chestnuts, willows, poplars, cottonwoods, birches, beech, etc. These trees are all characterized by their simple and inconspicuous flowers which are usually wind pollinated. Passing from these forms which in the older terminology are not in aptly described as apitalius There is the very large group of plants which have distinct and separate petals which are well described by the adjective polypedalis. It would be impossible in this space at command to adequately describe or even name the important plants which come under this head. As a type one might perhaps take the flower of the flax the parts of which are regular and symmetrical and show except in the ovary no fusion. But there may be wide departure from forms like these and the habit of considering any one flower as a type and the other forms as deviations from that type is one which the modern botanist eschews. It is not unreasonable to suppose however in a general way that the irregular flowers like the sweet pea for example have in the evolutionary sense been the result of later development than the simpler and symmetrical forms. One potent factor in the development of partial fusions and of flowers which are not radially symmetrical is probably that of the relation of the flower to insect visitation for the furthering of cross-pollination. A tendency is found in general toward modifications which as they can be interpreted make for the restrictions of the movements of insects or parts of insects among the floral organs and thus render more probable the carrying of pollen from one flower to another. The culmination of this tendency along with condition known as epigene, the insertion of the calyx, corolla and stamens on the ovary is seen in the sympathelius dichotoledinous type. In the sympathelius or gamopotelius flower the petals are fused into a bell or tube. A condition which may or may not be accompanied by other fusions. It is conceded that the compositi sunflower, daisy, asters which are of this sympathelius type represent the final and highest development of the dichotoledinous flower. Composites are found everywhere but are most numerous in temperate regions where they are usually herbs. The name of the family suggests a conspicuous feature, namely the organization of the numerous small flowers into a compact head which resembles a single flower formerly called a compound flower. So common are the composites that the general structure of the head should be understood. Taking the head of arnica as a type, the outermost set of organs consist of more or less leaf-like bracts or scales and volucur which resemble saples. Within these, there is a circle of flowers with conspicuous yellow corollus or rays which are split above the tubular base and flattened into a strap-shaped body and much resembling petals. Within the ray flowers is the broad expanse called the disc which is closely packed with very numerous small tubular flowers known as disc flowers. If a disc flower be removed it will be discovered that the ovary is inferior and that arising from it around the tubular corolla, there is a tuft of delicate hairs or papus which represent the saples. This papus surmounting the achine in composites may be lacking and of Section 23 Recording by Melanie Young Section 24 of the Science History of the Universe Volume 6 This is a LibriVox recording while LibriVox recordings are in the public domain. For more information or to volunteer, please visit LibriVox.org The Science History of the Universe Volume 6 Edited by Francis Rolt Wheeler Botany Chapter 5 Development of Morphology Part 1 We owe the term Morphology to Goethe to quote from Gable. He says Scientific men in all times have striven to recognize living bodies as such to understand the relations of their external, visible tangible parts and to interpret them as indications of what is within and thereby in some measure to gain a comprehensive notion of the whole. We find therefore in the march of art of knowledge and of science many attempts to found and construct a doctrine which we may name the Morphology. It is quite evident then that Morphology does not deal merely with the distinction and the naming of the outer parts of plants, although this which really belongs to terminology has been in part incorrectly called Morphology. Morphology does demand the knowledge of the different appearances of the members of the plant body but only as a means to an end. It requires not isolated facts but the relation of facts to one another. Terminology can be based on the study of dried plants but Morphology has as Goethe stated to do with living bodies which are involved in changes of a fixed character and are subjected to the influences exercised upon them by the outer world. It has in other words to do with that part of life phenomena which finds expression in the external configuration. In nature the form and function of an organ stand in the most intimate relation to each other. Herbert Spencer says everywhere structures in great measure determine functions and everywhere structures are incessantly modifying structures. In nature the two are inseparable cooperators and science can give no true interpretation of nature without keeping their cooperation constantly in view. An account of organic evolution in its more special aspects must be essentially an account of the interactions of structures and functions. The first question to which we have to find an answer is how came it that the functions of organs were entirely divorced from Morphology continues Gable. It is and rightly so one of the fundamental declarations of this study that the function of an organ tells nothing of its morphological significance. Or in other words the same function may be performed by organs of very different morphological value. Homologous organs must be distinguished from analogous ones. The tendrils of the vine and of the passion flower for example are chute axes whose leaves are entirely or almost entirely suppressed but the tendrils of the leguminose and of other plants although alike in form and function to those of the vine and passion flower are transformed leaves. The tendrils in the two cases are analogous. They are not homologous. This knowledge is one of the weightiest acquisitions of morphology but it has been the cause of an incorrect generalization because organs of like morphological significance may take on different functions the functions which they perform have been considered as of subordinate importance and therefore of no moment recognition of the characters of the organs. Hence it has been concluded that they must be entirely neglected in the grouping of the different members of plants in general categories. This conclusion is erroneous. It has led to an untenable position especially in that fundamental problem of morphology which from the time of Goethe has been styled the doctrine of morphophysis. By this we understand the fact that manifold as are the organs of plants they can be referred back to a few fundamental forms through whose transformation many and different members of the plant body have arisen. When we inquire how these primary forms and their transformations have been represented to us we meet with different conceptions that are part of those authors who have taken pains to reflect upon the idea with which they dealt. In the idealistic morphology as it was expounded by Goethe A. Brown and Hans Steen the doctrine of metamorphosis concerned itself with an essentially theoretical construction. Goethe himself has plainly stated his view as follows That which according to our idea is equal may in reality appear either as equal or as similar or indeed is completely unequal and dissimilar. This is the essence of the plant life of nature. In somewhat other form this idealistic notion has been preserved in as much as the history of development was raised by the labors of K. F. Wolf R. Brown and Schleiden to the rank of one of the most important aids to organography. The view which I have called the differentiation theory is based as indeed the whole of the doctrine of metamorphosis on the study of the transformation of leaves, the manifold character of which is well known. The differentiation theory assumes that at the vegetative point of the shoot indifferent primordia arise which are capable of development according to the needs of the plant in manifold ways but have this in common they are leaves. The other view assumes a real transformation of a primordium in such a way that, for example the primordium of a foliage leaf instead of developing actually into a foliage leaf can become in the mature condition a leaf of quite a different character. That the study of morphology should not have developed as rapidly as that of systematic is not to be wondered at and other than the passing references which will be found it would be purposeless to dilate upon the crude ideas of the earlier writers. While it cannot be said that he was by any means the first to consider morphological problems, in many ways decandoles work afforded a sounder foundation for proper morphological conceptions than most of his predecessors. The efforts of Jusso, Bicandole, and Robert Brown were directed to the discovery of the relationship between different species of plants by comparing them together, says Sacks. The doctrine of metamorphosis founded by Goethe set itself from the first to bring to light the hidden relationship between the different organs of one and the same plant. As Dicandole's doctrine of symmetry derived the different species of plants from an ideal plan of symmetry or type so the doctrine of metamorphosis assumed an ideal fundamental organ from which the different leaf forms in a plant could be derived. The stem came into consideration only as carrying the leaves. The root was almost entirely discarded. As the resemblance of nearly allied species of plants suggests itself naturally and unsought to the mind of the unbiased observer so also does the connection between different organs of a leafy nature in one and the same plant. Goethe's conception of the matter was from the first much less clear and chiefly because he was never able to bring the abnormal into its true connection with the normal or ascending metamorphosis. In the first sentence of his doctrine of metamorphosis 1790 he says that is open to observation that certain exterior parts of plants sometimes change and pass into the form of adjacent parts either wholly or in greater or less degree. In the cases of which Goethe is here thinking a distinct meaning can be fixed to the word metamorphosis. If for example the seeds of a plant with normal flowers produce a plant which has petals in place of stamens or in which the ovaries are resolved into green expanded leaves it is actually the case that a plant of a known form has given rise to another plant of a different form. In other words a change or metamorphosis has really taken place. But we cannot reason in this way in the case of that which Goethe calls normal or ascending metamorphosis. For the plant taken as constant the idea of metamorphosis has only a figurative meaning. The abstraction performed by the mind is transferred to the object itself if we ascribe to it a metamorphosis which has really taken place only in our conception. The case would be different if we could assume that the stamens and other organs of the plants lying before us were ordinary leaves in their progenitors. So long as this assumption of an actual change is not even hypothetically made the expression change or metamorphosis is a mere idea. This distinction Goethe has not made. He did not clearly see that his normal ascending metamorphosis can only have the meaning of a scientific fact if a real change is assumed to take place in the course of propagation, in this case as in that of abnormal metamorphosis or misinformation. In the years immediately before and after 1840 a new life began to stir in all parts of botanical research. In anatomy, physiology and morphology. Morphology was now specially connected with renewed investigations into the sexuality of plants and to embryology and attention was no longer confined to the fenerograms or flowering plants but was extended to the higher and later on to the lower cryptogams or flowerless plants. The Old Division of Linnaeus. These researches into the history of development first became possible when Van Moll had restored the study of anatomy and Nigele had founded and elaborated the theory of cell formation about the year 1845. The success of both these inquirers was due to the previous development of the art of microscopy. It was the microscope which revealed the facts on which the foundations of the new research were laid, while its promoters at the same time started from other philosophical principles than those which had hitherto prevailed among botanists. Serious attention to microscopy was one of the causes which introduced the best observers to the practice of inductive inquiry and gave them an insight into its nature and in a few years time when the actual results of these investigations began to appear and when a wholly new world disclosed itself to botanists, especially in the cryptogams, then questions arose on which the dogmatic philosophy had not assayed its ancient strength. The facts and the questions were new and untouched and presented themselves to unprejudiced preservation in a purer form than those which during the first three centuries had been so mixed up with the old philosophy and with the principles of scholasticism. Von Moll, who only occasionally occupied himself with morphological subjects, says Sacks, was a firm adherent of the inductive method and was bent on the establishment of individual facts rather than general principles. But the founders also of the numorphology, Schleiden and Negelli, started from philosophical points of view which, different as they were in the two men, had yet two things in common. A demand for severely inductive investigation as the foundation of all science and the rejection of all teleological modes of explaining phenomena in which latter point, their opposition to the idealistic nature philosophy school was most distinctly manifested. They had indeed one very important point of contact with the school. The belief in the constancy of organic forms, but this belief not being connected with the platonic doctrine of ideas, was with them only a recognition of everyday observation, and was therefore of less fundamental importance, being felt merely as an inconvenient element in the science. Treating the question in this way and influenced by the results of the new researchers, they either inclined to entertain the idea of descent before the appearance of Darwin's great work, or gave a ready ascent to the principle of the new doctrine, though expressed some doubts respecting matters of detail. Hofmeister's researches in morphology and embryology, threw an entirely new light on the relations of affinity between the great groups in the vegetable kingdom, and were leading more and more to the view that there must be some special peculiarity in the question of the constancy of organic forms. But the idea of evolution in the vegetable kingdom brought more distinctly home to men's minds by paleontological researches. Unger especially, while advancing the knowledge of the structure of cells and of vegetable anatomy and physiology, and generally taking a prominent part in the development of the new botany, applied the results of its investigations to the examination of primeval vegetation, and showed the morphological and systematic relations between past and existing florists. After twenty years of preliminary study, he declared distinctly in 1852 that the immutability of species is an illusion that the new species which have made their appearance in geological periods are organically connected, the Unger having arisen from the Elder. In the year that Darwin's book on the origin of species appeared, Gele wrote, external reasons, supplied by the comparison of the florists of successive geological periods, and internal reasons given in physiological and morphological laws of development, and in the variability of the species, leaves scarcely a doubt that species have preceded one from another. Though these words might not contain a theory of descent capable at once of scientific application, yet they show that the latest researches and candid appreciation of facts were compelling the most eminent representatives of the botany of the day to give up the constancy of forms. At the same time, in the genetic morphology, which had developed itself mainly under Negelli's guidance since 1844, and still more in embryology, which in Hofmeister's hands was leading to results of the greatest systematic importance, there lay a fruitful element, destined to correct and enrich Darwin's doctrine of descent in one essential point. That doctrine, in its original form, sought to show that selection, the result of the struggle for existence, combined with perpetual variation, was the sole cause of progressive improvement in organic forms. But Negelli, relying on the results of German morphology, was able, as early as 1865, to point out that this explanation was not satisfactory, because it leaves unnoticed certain morphological relations, especially between the large divisions of the vegetable kingdom, which scarcely seem explainable by mere selections and breeding, while Negelli showed that Darwin's principle of selection was well adapted to explain fully the adaptation of organisms to their environment, and the suitableness and physiological peculiarities of their structure. He pointed out that in the nature of plants themselves there are intimations of law of variations, which lead to a perfecting of organic forms, and to their progressive differentiation independently of the struggle for existence, and of natural selection. The importance of this result of morphological research has since been recognized by Darwin. Thus, Negelli supplied what was wanting in the theory of descent and gave it the form in which it is adequate to explain the problem already recognized by the systematists of the old persuasion, namely how it is possible for the morphological affinity of species in the system to be in so a high degree independent of their physiological adaptation to their environment. Modern teaching on vegetable cells, modern anatomy, and morphology, and the improved form of the theory of selection are the product of inductive inquiry since 1840. It is one of the characteristic features of the theory of botany that morphology enters into the closest connection with the doctrine of the cell with anatomy and embryology and that researches, especially into the process of fecundation and the formation of the embryo form to some extent the central point of morphological and systematic investigations. At this time when there was such a necessity for general critical coordination and attack on the methods of the day, Schleiden began his writing and all his work were to be found side by side with facts of real importance, reflections of the man himself and generally coarse polemic, coupled with a free praise or blame of other workers. Schleiden's greatest contribution was his establishment of the true nature of the cell and the propounding of what may be called the cell doctrine of the structure of plants. This was published in 1848, a year before the appearance of a similar contribution by Schwann as regards animal forms. Both of these investigations mark a new epic in the study of the structure of organic forms and from that the researches into the inner morphology of plants made rapid progress. Schleiden's mode of dealing with the natural system must be reckoned among the good services which he rendered to method, not because his classification of the vegetable kingdom presents any specially interesting features or brought to light any new affinities, but because we see an attempt made for the first time to give detailed characters drawn from morphology and the history of development to the primary divisions and because by this means the positive and distinct nature of the cryptogams was from the first clearly brought out. The old way of treating morphology as though there were only Phanaro-gams in the world and then having recourse to unmeaning negatives in dealing with the cryptogams was thus set aside, much to the profit of the immediate future which directed its attention especially to the cryptogams. End of Part 1 End of Section 24 Section 25 of the Science History of the Universe Volume 6 This is a LibriVox recording while LibriVox recordings are in the public domain. For more information or to volunteer please visit LibriVox.org The Science History of the Universe Volume 6 Edited by Francis Rold Wheeler Botany Chapter 5 Development of Morphology Part 2 Soon after Schleden first stirred the scientific world a man of a very different character of mind began to address himself to the great task. This was Carl Nigelli whose researches from this time onward laid the foundations of knowledge in every department of botany. Like others he felt the necessity of first determining his position with respect to the philosophical principles of the investigation of nature but he did not proceed to give a general exposition of the inductive method as opposed to the dogmatism of the idealistic school. He went straight to the application of the laws of induction to the most general problems of organic nature and specially of vegetation. It is easy to say remarks von Sachs treating of his work that the task of natural science is simply to deduce conceptions and laws from the facts of experience by aid of exact observation. Many considerations present themselves as soon as the attempt is made to satisfy this demand for it is not enough merely to accumulate individual facts. The point to which the inductive inquiry is to lead must be kept constantly and clearly before the mind. Nigelli insisted that it is only in this way that facts and observations of any scientific value that the one important thing is to make every single conception obtained by induction find its place in the scheme of all the rest of our knowledge. Since in nature everything is in movement and every phenomenon is transitory, presenting itself to us in organic life especially as the history of development all do regard must be paid to this condition of constant motility informing scientific conceptions. History of development is not merely to be treated generally as one of various means of investigation but as identical with investigation into organic nature. Nigelli set himself in earnest to meet the demands of inductive inquiry such as he had himself described them. Moreover he connected his own morphological investigations as far as possible with the lower cryptogams extending them afterward to the higher cryptogams and to the fenerogams that is he proceeded from simple and plain facts to the more difficult thus not only introducing the cryptogams into the field of systematic investigation but making them its starting point. In this way morphology not only secured a foundation in exact historical development but it assumed a different aspect in as much as the morphological ideas hitherto drawn from the fenerograms or now examined by the light of the history of development in the cryptogams. This was one innovation the second closely connected with it was the way in which Nigelli made the new doctrine of the cell the starting point of morphology. Both the first commencement of organs and their further growth were carried back to the formation of the separate cells and the remarkable result was to show that in the cryptogams especially whose growth is intimately connected to the formation precise conformity to law obtains in the succession and direction of the dividing walls and that the origin and further growth of every organ is affected by cells of an absolutely fixed derivation. The most remarkable thing was that every stem and branch every leaf or other organ has a single cell at its apex and that all succeeding cells are formed by division by fixed laws so that the origin of all cell tissue can be traced back to an apical cell. While important fragments as to their life histories and structures were described they had little connected scientific value save perhaps the discovery that the fertilization in certain cryptogams as in animals was effected by spermatozoids as to the flower in the plants and the formation of the pollen tube and of the development of the embryo was not at all understood. This important question was set at rest by Wilhelm Hofmeister. He showed that the egg cell is formed in the embryo sac before fertilization and that it is this which is excited to further development by the appearance of the pollen tube and produces the embryo. Hofmeister had observed the organization of the ovule the nature of the embryo sac and of the pollen green and the formation of the embryo from the fertilized egg cell step by step and cell by cell and his account of these processes was aided by the light which Negelli's theory of the cell and his reference of all processes of development to the processes of cell formation had thrown upon the history of development. He went on to apply the same method to the study of the embryology of the mosses and the vascular cryptogams and followed the development of the sexual organs cell by cell in a large number of species. The intimate connection between such different organisms as the live of warts, the mosses, the ferns, the horsetails, the club mosses, the conifers, the monocotyledons and dicotyledons could now be surveyed in all its relations with the stankness never before attained. Alternation of generations lately shown to exist though in quite different forms in the animal kingdom was proved to be the highest law of development and to reign according to a simple scheme throughout the whole long series of these extremely different plants. It appeared most clearly in the ferns and mosses though at the same time with a certain difference in each in the ferns and allied cryptogams a small and conspicuous body grows out of the asexually produced spore and immediately produces the sexual organs. From the fertilization of these organs proceeds the root bearing and leafy stem of the fern which in its turn again produces only asexual spores. In the mosses on the other hand a much differentiated fully long-lived plant is developed from the spore and this plant proceeds again after some time to form sexual organs the product of which is the so-called moss plant the first generation that arose from the spore the sexual is in the moss, the vegetative plant while in the ferns and their allies the whole fullness of vital activity and of morphological differentiation is unfolded in the second generation which is asexually produced. Here all was at once clear and obvious but Hofmeister's researches also showed that the same scheme of development holds good in the rhizocarp and celiginelli where two kinds of spores are formed and it appeared plainly from their case that the recognition of the true relation between the production of spores and sexual organs matched the guide to the morphological interpretation when the processes and the large female spore of the most perfect of the cryptogams was known the formation of the seeds and the conifers was at once understood the embryo sac in these answered to this large spore while the endosperm represented the prothalium and the pollen grain the microspore the last trace of alternation of generations so obvious in the ferns and mosses was seen in the formation of the seed in the fenerogams the changes which the alternation of generations passes through from the mosses upward to the fenerogams were, if possible still more surprising than the alternation of generations itself. The reader of Hofmeister's Vergleichende und Tussuchen was presented with a picture of genetic affinity between cryptogams and fenerogams which could not be reconciled with the then reigning belief in the constancy of species he was invited to recognize a connection of development which made the most different things appear to be closely united together the simplest moss with palms, conifers and angiospermus trees and which was incompatible with a theory of original types the assumption that every natural group represents an idea was here quite out of place the notion entertained up to that time of what was really meant by the natural system had to be entirely altered it could as little pass for a body of platonic ideas as for a mere framework of conceptions but the effect of the work was great in respect to the system also the cryptogams were now the most important objects in the study of morphology the mosses were the standard by which the lower cryptogams must be tried the ferns were the measure for the fenerogams embryology was the thread which guided the observer through the labyrinth of comparative and genetic morphology metamorphosis now received its true meaning when every organ could be referred to its parent form the stamina and capillary leaves of the fenerogams for example to the spore bearing leaves of the vascular cryptogams that which hacle after the appearance of Darwin's book called the phylogenetic method Hofmeister had long before actually carried out and with magnificent success when Darwin's theory was given to the world eight years after Hofmeister's investigations the relations of affinity between the great divisions of the vegetable kingdom were so well established and so patent that the theory of descent had only to accept what genetic morphology had actually brought to view but the algae, fungi and leachens presented a chaotic mass of obscure forms in contrast with the well ordered knowledge of the mosses and vascular plants there was a difficulty in drawing the boundary line between the lower animals and plants the difficulty was solved by classing all objects capable of independent movement with animals thus whole families of algae were claimed by the zoologists and when the swarm spores of the genuine algae were seen for the first time in the act of escaping the phenomenon was described as the changing of the plant into an animal such was the condition of affairs with respect to the algae about the year 1850 when Hofmeister made the formation of the embryo in the Phanerograms the vascular cryptogams and the mosses the central point of investigation in morphology and systematic botany he made it clear that a perfect insight into the whole cycle of development and into its affinities can only be obtained in making its sexual propagation the first commencement of the embryo the starting point of the investigation it was natural to expect as happy results from the embryology of the algae as had been obtained in the case of the higher plants it was important therefore that the observer should no longer rest satisfied with a knowledge of the sexual multiplication of the algae he must inquire into their asexual propagation and by its aid discover the complete history of their development former observations suggested the probability that here too sexual propagation is the prevailing rule a splendid result appeared in 1853 in Tourette's account of the fertilization of the genus Fuchus this was a simple process as a matter of embryology but the sexual act was so clear and even open to experimental treatment that it threw light at once upon other cases more difficult to observe then followed discoveries by different workers of sexual processes and rapid succession Pringzheim however was not content with carefully observing the sexual act he gave detailed descriptions of growth in the same families in its progress cell by cell of the formation of the sexual organs and the development of the sexual product the asexual propagations which are intercalated into the vegetation and embryology were shown in their true connection processes were recognized which often recalled the alternation of generations in the mucinette it was shown that very different forms of sexuality and of general development occur in the algae and these led to the formation of systematic groups quite different from those founded on the superficial observation of collectors from the confused mass of forms not before understood Pringzheim brought out a series of characteristic groups which thoroughly examined and skillfully described in words and by figures stood out as islands in the chaotic sea of still unexamined forms and through light in many ways on all around them the algae offer at present a great variety in the processes of development than any other class of plants sexual and asexual propagation and growth work one into the other in a way which opens entirely new glimpses into the nature of the vegetable world some useful observations also had been accumulating for some time on the fungi as early as 1729 P. A. Michelli 1679-1737 had collected the spores of numerous fungi had sewn them and obtained not only mycelia but also spore of forests fructifications yet Rudolfi and Link at the beginning of the last century ventured to deny the germination of the spores of fungi persumed in 1818 thought that some fungi grew from spores others from spontaneous generation the study of the lower fungi presented many difficulties but by the method of carefully working out complete life histories or at least attempting to do so progress was being made to the brothers to lasny belongs the credit to first breaking ground in this direction but mycology owes its present form to none more than to Anton de Barry with a correct understanding of the only means which can lead to sure results in this difficult branch of study de Barry made it his first endeavor to perfect the methods of observation and not only sought for the stages of development of the lower fungi in their natural places of growth but cultivated them himself with all possible precautions and thus obtain complete and uninterrupted series of developments by these means he succeeded improving that parasitic fungi make their way into the inside of healthy plants and animals that this is the explanation of the remarkable fact that fungi live in the apparently uninjured tissue of other organisms a fact which formally had led to the supposition that such fungi owe their origin to spontaneous generation or to the living contents of the cells of their entertainers Pring-Sime had already observed these occurrences in 1858 in the case of an unusually simple water fungus, Pythium de Barry showed that the intrusive parasite vegetates inside the plant or animal which is its host and afterward send out its organs of propagation into the open air and that at a given time the organism attacked by the fungus sickens or dies these investigations were not only of high scientific interest to the biologist but they produced a series of results of the greatest importance to agriculture and forestry and even to medicine with the fungi more than the algae the chief difficulty in making out a complete series of developments in the history of each species arose from the frequent intercalation of the asexual mode of multiplication into the course of its development and in the further peculiarity that the several stages of development in some cases could only be completed on different substrates one of the most important tasks was to refine the sexual organs the existence of which was rendered probable by various analogies and after de Barry had observed the sexual organs in the Piranospore in 1861 he succeeded in 1863 in proving for the first time that the whole fruit body of an asco mycete is itself the product of the sexual act which takes place on the threads of the mycelium but the most important result remains to be told it is that the two classes of algae and fungi hitherto kept strictly separate must obviously be now united and an entirely new classification adopted in which algae and fungi recur as forms differing only in habit in various divisions founded on their own morphology a few words must be given here to lesions they are the division of the phallophytes whose true nature was last recognized and that only in modern times till after 1850 scarcely more was known of their organization than Walroth had discovered in 1825 namely that green cells known as gonidia are scattered through the fungus-like hyphal tissue of the phallus after moles investigation in 1833 it was known that free spores were formed in the tubes of the fructifications apothecia and that a dust collected from the phallus and consisting of a mixture of gonidia and hyphae was in a condition to propagate the species the genetic relation between the chlorophyll containing gonidia and the fungus-like hyphae long continued to be obscure till at last after 1868 it was shown that the gonidia are true algae and the hyphal tissue a genuine fungus and that therefore the lesions are not a class coordinating with the algae and fungi but a division of ascomycetes which have this peculiarity that they spin their threads round the plants on which they feed and take them up in their tissue end of chapter 5 end of section 25 section 26 of the science history of the universe volume 6 this is a LibriVox recording all LibriVox recordings are in the public domain for more information or to volunteer please visit LibriVox.org recording by Madison Rutherford the science history of the universe volume 6 edited by Francis Rottweiler botany chapter 6 organogony and adaptation reference has already been made to the service which Sliden did in promulgating the idea of the cell as the morphological unit of plant structure as will be seen he was not indeed the first to observe them though he was the first to properly understand their significance since the cell is the ultimate unit to which morphological discussions must necessarily hark back it is well to examine a little more closely just what these cells are a thin cross section from the stem or leaf of any plant shows when magnified a network of cells not unlike those of the honeycomb this fact was first discovered in 1667 by Robert Hook an Englishman who happened to take such a section to test the improvements he was making on the microscope the first real study of cell structure was made by Malfigi an Italian in the year 16171 the section thus examined appears to be divided into small chambers or cavities separated from each other by a common wall the single cavity with its enclosing wall like a room in a house received the name of cell the origin of these cells or elements of plant structure was at first supposed to be similar to that of air bubbles in a somewhat viscous liquid but this supposition was soon found untenable as in no young growing tissues was there found any indication of the liquid in which the bubbles were supposed to form at a much later period it was discovered that the wall or membrane which gave the name to the cavity which it surrounds was really the less important part and that the cell contents were the only necessary element this is shown by the fact that the wall is a product of the contents and that at certain periods of the plant's life the cell may exist without it discoveries of this kind gave rise to entirely different conception of the nature of the plant cell it is now known that this and its simplest or least differentiated condition consists of a small portion of the viscous liquid known as protoplasm in which under ordinary magnification no structures are visible it is in this general sense that Reiki defines a plant cell as follows an individualized not further divisible structure consisting of or containing protoplasm which either shows life processes or has shown them in studying the anatomy of a plant cell says E. L. Gregory and elements of plant anatomy it will be necessary to consider one in its ordinary condition of development that is as an element of any plant differentiated sufficiently to perform the ordinary functions of plant cells such cells are usually considered as consisting of two parts wall and sentence as it is frequently stated wall and protoplasm the latter including a nucleus and one or more vacuoles before taking up the study of these parts separately it may be well to examine the cell as a whole in reference to several features namely size, form mechanical and physiological principles and finally to discuss briefly certain theories concerning organized structures in general by far the greater number of plant cells are microscopic but they vary in size the smallest occur among the organisms known as bacteria some of these are spherical in form and measure from 7 tenths to 1 micromilometer in diameter cells vary as much in form as in size those without a membrane inclined to the spherical shape since the protoplasm composing them is in a half liquid state many swarm spores are pear shaped but they generally assume a spherical form oncoming to rest on the subject to rapid change in all the higher plants new cells are formed by the growth of walls across the cavities of the old cells the new walls join the old at certain angles and when the cells are young they are inclined to a hexagonal form as growth continues the form is liable to change in various ways if the cell should grow equally fast in all parts it would tend to retain its original form this very rarely happens and even when it does such a cell is influenced in a greater or less degree by the manner of growth of those surrounding it as the growing wall is flexible in its shape easily changed by pressure or traction from without the individuality of the cell is shown by the fact that each has its own predetermined manner of development all young cells of any plant are at first nearly similar in form and size but later on each cell is seen to follow certain laws of growth which are to a certain extent independent of all external forces from these laws together with various mechanical causes arises the great variety of form in the cells of ordinary plants the peculiar forms common to certain unicellular plants illustrate even better than those of higher ones the inherent tendency of cells to grow in a certain manner from the small size of the average cell two advantages result to the plant first, strength and solidity secondly, the greatest possible amount of surface for the transfer of cell contents the first ensures mechanical support the second is connected with those changes in the chemical nature of the cell contents by which the life processes of the plant as a whole are carried on Herbert Spencer included a consideration of plants in his scheme of the principles of biology however, some of his deductions may be regarded at the present time the fact remains that he summed up in at least a convenient form the ideas of morphological differentiation as influenced by the idea of evolution it is true that Spencer's knowledge of plants was much of its second hand but his treatment of the subject was a philosophical one and in the main sound the problems of morphology fall into two distinct classes answering respectively to the two leading aspects of evolution evolution, says Spencer in his principles of biology implies insensible modifications and gradual transitions which render definition difficult which make it impossible to separate absolutely the phases of organization from one another thus on inquiring what is the morphological unit whether a plant or of animals we find that the facts refuse to be included in any rigid formula the doctrine that all organisms are built up of cells or that the cells are the elements out of which every tissue is developed is but approximately true there are living forms of which cellular structure cannot be asserted and in living forms that are for the most part cellular there are nevertheless certain portions which are not produced by the metamorphosis of cells obviously the earliest forms must have been minute since in the absence of any but diffused organic matter no form but a minute one could find nutriment obviously too it must have been structureless since as differentiations are producible only by the unlike actions of incident forces there could have been no differentiations before such forces had had time to work hence, distinctions of parts like those required to constitute a cell were necessarily absent at first and we need not therefore be surprised to find, as we do find specks of protoplasm manifesting life and yet showing no signs of organization a further stage of evolution is reached when the imperfectly integrated molecules forming one of these minute aggregates become more coherent at the same time as they pass into heterogeneity gradually increasing in its definiteness that is to say we may look for the assumption by them of some distinction of parts such as we find in cells and in what are called unicellular organisms they cannot retain their primordial uniformity and while in a few cases they may depart from it slightly they will and the great majority of cases acquire a decided multi-formity there will result the comparatively integrated and comparatively differentiated protophyta and protozoa the production of minute aggregates of physiological units being the first step and the passage of such minute aggregates into more consolidated and more complex forms being the second step it must naturally happen that all higher organic types subsequently arising by further integrations and differentiations will everywhere bear the impress of this earliest phase of evolution of heredity considered as extending to the entire succession of living things during the earth's past history it follows that since the formation of these small simple organisms must have preceded the formation of larger and more complex organisms the larger and more complex organisms must inherit their essential characters we may anticipate that the multiplication and combination of these minute aggregates or cells will be conspicuous in the early developmental stages of plants and animals and that throughout all subsequent stages cell production and cell differentiation will be dominant characteristics the physiological units peculiar to each higher species will speaking generally pass through this form of aggregation on their way toward the final arrangement they are to assume because those primordial physiological units from which they are remotely descended aggregated into this form gobel more recently and it is said that the of my certain socks as one who has contributed in a special degree to the science of organography has preceded along somewhat similar lines though with a far wider knowledge of the actual facts in discussing the question of the elaboration of the plant body his introductory statements are illuminating it is manifest he says that the distinction of organs must have originally been based indicates that the original conception of a leaf was that of a flat organ which was distinguished by this character from the usually cylindric stem under the designation route all subterranean organs were reckoned it is however now generally known that there are leaves which have all the appearance of shoots and the converse is also the case external form is closely connected with function and with anatomical structure in the vegetative organs the form may change, accompanied by a change in anatomical structure metamorphosis may take place and a flower leaf is the amalogue of a foliage leaf not withstanding that it has quite a different form the history of development of the stem of the leaf is usually different and the first place the duration of development is unlike leaves have limited growth shoots have unlimited growth but there are many shoots which normally exhibit limited growth for example the short shoots or spur shoots of many conifers and broadleaf plants in the world in this genus the floating shoots of the water form as well as the creeping stolons of the land form are homologous with leaves but the difference between stem and leaf has entirely disappeared the organs which are homologous with leaves produce flowers and other shoots and exhibit unlimited growth and that they are really leaves with prolonged apical growth is only to be determined by a careful comparative study every distinction then that we may draw between shoot and leaf is only relative is not fundamental there is however this point still to notice leaves are in most cases outgross of shoe axes and they arise on their vegetated point as lateral members nevertheless terminal leaf organs organs arising from the end of a shoe axis are known they occur in the flowers of many plants the codilodon and many monocodiladenous plants is terminal in the embryo there are also monocodiladenous embryos upon which leaves arise although no vegetated point of the axis is visible and a similar condition is also found in iso eats further the vegetated body of lemna is nothing else than a leaf producing leaves it is not a leafless twig as is commonly assumed a plant body in which the shoe axis does not exhibit differentiation into stem and leaf is termed a thallus the expression thallus which signifies nothing more than shoot was first used by acrius in describing the lichens and subsequently it was extended to the algae the fungi and the thallus liverworts there is no sharp limitation between a thallus and a leafy shoot the external relationships of configuration of the bodies of plants are determined by the peculiarities of their living substance the protoplasm which in the higher plants is enclosed within the numerous cells which compose the plant it is only among the lower plants that we find unicellular bodies in lamb plants the cellular structure is general and the several cell chambers are separated from one another by firm walls here gobel speaks of socks definition of the entergid as the unit of cell structure quoting socks you says entergid I mean a single nucleus with the protoplasm which it dominates thus he distinguishes the moneragic type of plant which is unicellular but has a single nucleus i.e. is a single entergid and the polyeragic forms which have many entergids that are usually separated into individual cells by cell walls though in some of the lower forms they may not be it has been possible he continues in a large number of cases to discover a relationship between their forms and their life functions we see this for example among diatoms the moneragic cells of fixed species have a different construction from that which obtains in the actively moving or floating species it is also clear that the paralike form of most swarm spores is especially favorable for their movements in other cases however we know so little regarding the special life relationships of the plants that we are quite unable to speak with certainty we cannot for example say whether the rod-like or sickle-like desmids have relationships of a kind different from those of the plate forms the degree in which the single entergids are united with one another may be more or less intimate a polyeragic plant is either an entergid colony or synobium cellular or non-cellular in which a division of labor between the several entergids has not yet appeared and each entergid is capable of living for itself or the entergids exhibit a division of labor and although in unison with one another are there in different from one another they form an entergid dominion this is what has come to pass in the majority of the polyeragic plants there are of course many transitions between these two conditions and their separation is a measure artificial being based upon extreme relationships in the higher plants the shoe is differentiated into shoe axis and leaf in all cases except in some degenerate parasites there are, it is true, leafless shoots of limited growth but these are quite exceptions in the lower forms of plant life such a differentiation of the shoe may also take place the sexual generation of many liverworts and of the whole of the mosses shows an evident division into shoe axis and leaf and as has been above explained this addition is reached among the liverworts and the most different cycles of affinity which have developed quite independently one of the other that the leaves of the sexual generation of mosses are not homologous with those of the asexual generation of the pterodephida is sufficiently clear but terminology is only a means to an end and I have no hesitation in calling the leaf like organs which we find in many phthalophyta leaves the development of morphology both as it applies to cell and tissue structure alone and as it applies to the study of life histories has made rapid advances in the last few decades there have been and are numerous keen investigators covering all morphological fields the present knowledge of the structure of the individual cell has greatly increased and the store of information regarding the embryology of the higher plants though founded on the classic work of Hofmeister is well nigh a new science the study of life histories and as complete a way as possible is now the aim of morphological investigators the morphologist says H. M. Richards who devotes his time to the study of life histories is engaged in the work of tracing the race history plants from the comparison of the individual development of more or less nearly related forms thus the homologies which have been traced among the flowering plants and the nearest allies among the ferns and other forms indicate to us the probable race history of these groups it is true that the beginning of this work dates back some decades but it is still to a large extent an open field and numerous investigators are actively prosecuting research along these lines for example the alternation of a sexual and non-sexual generation of plants which has long been known as characteristic of the life histories of higher forms has recently been established among the lower groups and thus a much clear view of the whole series of the plant kingdom is being obtained the branch of botanical research known as ecology is one of the most inclusive it may be regarded as an attempt to grasp the full meaning of the morphological and physiological manifestations of the living plant not only as a concern itself but also in the relation to all factors of its environment whether with other organisms or with purely physical agents it is evident that the problem is a stupendous one and in the present state of knowledge both of physiology and morphology it cannot be expected that necessarily permanent results are to be obtained nevertheless it serves a highly important end in calling attention to and insisting upon the fact that environmental factors must influence the individual that no organism even a plant is a free agent in determining its career or the career of its progeny ecology is the application in a broad and more philosophical way of the methods of the physiological anatomist coupled with those of the taxonomist but in addition the work of the botanist touches the field of the physiographer and geologist ecology says H. M. Richards and his botany is the endeavor to uncover the plan of nature as it governs the relations of the different plant forms in a given area to understand the why and the where for of the association of very different forms in one locality the keynote of the philosophical development of this topic rests on the conception of the constant struggle of individuals or groups of individuals to maintain themselves against other forms which leads to a balanced relation of the different species in the given flora from the beginning one of the greatest of ecological problems has been that of the origin and significance of adaptations in other days remarks Henry C. cows and his trend of ecological philosophy the solution was sought in special creation one of the most unscientific of all theories because all together subversive of experiment the entire question was at the outset the theory of special creation however has not been especially harmful because it has generally seemed so unlikely as to have received but little support from scientific men perhaps the most painful of all ecological theories has been the Lamarckian theory of direct adaptation the theory of natural selection has worked great harm in the ecological study of plant structures thorny plants have been supposed to be selected by reason of animal incursion and such complex things as floral structures have been supposed to be the result of parallel selection on the part of flowers and insects there is no adequate evidence experimental or otherwise for views of this character such experimental work as has been done appears to show that the success or failure of a plant rarely depends upon this or that little advantage upon which natural selection may be supposed to work but rather that its perpetuation depends for the most part upon other things than its so-called adaptations few more perfect adaptations for their function can be thought of than the digestive glands of insectivorous plants and yet there is no evidence in support of the idea that such plants have been able to survive by reason of these glands the evolution of such a complex flower as that of the orchid along lines that are parallel with the evolution of the mouth parts of a special insect requires a nice operation that seems staggering and all the more because the flower at least seems to have evolved so far along the lines of psychomorphy as to be a source of disadvantage rather than of advantage an impossible idea to the natural selectionist the facts of regeneration show that plants and animals are often in a position to make an instant new reaction to conditions unlike those to which they have ever been accustomed and that these reactions may or may not be advantageous in any case natural selection can have no possible connection with their origin the trend of the time especially among botanists is unmistakably toward the abandonment of natural selection as a theory of evolution but ecological work is finding a dominant place for it as one of the controlling factors in succession the student of vegetative dynamics more perhaps than any other finds displayed before him an incessant struggle for existence in the changing conditions the fitness of an old species to remain or of a new species to displace it is commonly a matter profound importance in the vegetative change produced to the working ecologists the necessary consequences of the abandonment of the idea of adaptation and natural selection as a positive factor are most vital first and foremost there comes a possibility of disadvantageous trends in evolution to some extent such tendencies will be checked by the destructive operation of natural selection so that only such new species as our most fit are likely to survive and have progeny but in view of the ideas that have generally prevailed in past years it cannot be emphasized too strongly that plants may retain useless structures and even structures that are moderately harmful and yet live on if they also possess other structures or habits that are sufficiently advantageous this conception at once relieves ecologists of one of the most arduous of their former duties the establishment of an advantageous function for every organ and of a benefit in every function end of section 26 botany organography and adaptation recording by Madison Reutherford