CHAPTER XYI 



APPLICATIONS OF CHRONOPHOTOGRAPHY TO 

 EXPERIMENTAL PHYSIOLOGY 



Summary. — Numerous applications of chronophotography ; it supple- 

 ments the information derived from the graphic method— Study 

 of the movements of the heart by means of the graphic method — 

 Photography of the successive phases of cardiac action in a 

 tortoise under conditions of artificial circulation — Variations in 

 shape and capacity of the auricles and ventricles during a cardiac 

 cycli — Mechanism of cardiac pulsation studied by means of 

 chronophotography — Comparative advantages of mechanical and 

 chronophotographic registration — Determination of the centres of 

 movements in joints. 



Almost all vital functions are accompanied by move- 

 ment ; but any attempt to investigate them is beset 

 with extreme difficulty, for the majority of them are 

 very complicated or very rapid. Sometimes, on the 

 other hand, they are extremely slow and difficult to 

 observe. 



The methods employed by physiologists are gene- 

 rally devised with a view to elucidate what the unaided 

 eye cannot discover for itself. 



It might reasonably be predicted that chronopho- 

 tography might be found useful in this domain. It 

 might show, for instance, the part played from moment 

 to moment by the different parts of the thorax in the 

 act of respiration. It might follow the peristaltic and 

 the antiperistaltic contractions of the intestines through 

 all their phases and under the various conditions which 

 modify the characters of these movements. In a word, 



