 Pigmentation in the iris has the same function as it does in the skin, protection against strong sunlight. And pigmentation or the degree of pigmentation is the primary indicator of constitution. So primary constitution is a colour typology. In a dark iris the pigmentation permeates the whole iris. In a light brown or hazel iris the pigmentation is partial. We'll see some pictures of this in a minute. And a blue or blue grey iris has little or no pigmentation. And as we've said before the blue in a blue iris comes from the base leaf or the pigmented epithelium of the iris. Which is a midnight blue layer of tissue that lies behind all the fibres that we can see in that complicated structure that we've been looking at. So here are our three primary constitutional types. And this is a little bit of a preview of what we're going to be doing next in our next lesson. And we're going to start putting the names in here too. The correct iridological constitutional names. So for the blue iris no pigmentation. Because pigmentation in the iris is always in the yellow brown red spectrum. And we call this the lymphatic type. And you can already start to see lymphatic. That's got to be something to do with the lymph and the lymph system. You'd be absolutely right. We'll discuss that in more detail as we go through. Next to that we have the intermediate type. Brown grey or sometimes described as hazel. And the thing about this is that it can be quite pale or it can be almost completely dark. It's a very wide range of, you know, spectrum of colour that you can see in this particular type. We call this the mixed type because it is a mixture of the two pigmented and unpigmented. Sometimes also called the mixed biliary type. And that word biliary refers to the liver and gallbladder. So we know there's something to do with liver, something to do with the gallbladder, maybe to do with digestion affecting these types. And then lastly on the right hand side we have the pure dark brown iris. That's fully pigmented with no, and you can see in the mixed iris in the middle that you can't see much of the fibre structure in the middle where the pigment is densest, but as it fades towards the edge of the iris you can start to see the fibres underlying it. Whereas in the far right picture, the dark brown iris, you see no fibre structure, at least not in the ciliary zone. And the name that we give to that is hematogenic. And those of you who are familiar with your anatomical language might already know that that's going to have something to do with blood. So blood composition is the important factor in determining that particular constitutional type. And that's the primary classification. We have a lot more detail to add to that in the next class, but that's where we start with our constitutional analysis by looking at what colour the iris, and then asking relevant questions about the individual's health experience. If you enjoyed this video, please give it a like and subscribe below so you don't miss any future content. To learn more about CNN or its courses, head to www.naturopathy-uk.com