 New students, in this topic we shall discuss chymography. A chymograph is an instrument that graphically records changes in the mechanical activities of animal tissues. The word chymograph comes from the latent word which means wave writer. This term is used because of the graphical records produced by this instrument. The chymograph is used in physiological experiments related to the study of skeletal muscle contractions, for example twitch and tetanus. It is also used to study the cardiac muscle activities, for example cardiac cycle. It is also used for the measurement of blood pressure and rate of respiration. A chymograph apparatus consists of a revolving drum to which a writing stylus is attached. The stylus records changes over time on a paper, which is surrounded by this drum. Every drum moves or revolves, these writing pens and stylus are made and run. Dear students, now we shall take an example of chymography of frog's heart, which is generally carried out in physiology labs. This chymography provides us an understanding of the cardiac cycle of frog. It also gives the clues of the site of origin of heartbeat in frog and its control. It also provides us the understanding of coordination of contractions of chambers of the heart. The diagram or graph we are seeing here is a chymograph of frog's heartbeat. In which we can see different phases in which the contraction of sinus venousus occurred on the face. The contraction of oracles is also shown with a wave deflection or the deflection of ventricles is also shown. This pattern is repeated for the heartbeats of frog's heart. Dear students, chymography also helps us to study the effect of various factors on cardiac output. For example, when we want to study the effect of temperature or various ions or acetylcholine or epinephrine, we use chymography.