278 MOVEMENT 



the heart, he would derive from the curves an exact 

 knowledge of the blood-pressure obtaining in the 

 cardiac chambers, and of the ever-changing force to 

 which the exploring apparatus was exposed in its con- 

 tact with the ventricular walls. Further, he would 

 notice the exact sequence of these changes : but from 

 these curves alone he would gain no information con- 

 cerning the organ which brought about these changes. 

 It would be possible for him to picture to himself a 

 system of pistons, pumps, and valves capable of pro- 

 ducing similar results, but he would never succeed in 

 realizing the actual shape of the heart and the altera- 

 tion in appearance and volume which the different 

 cavities of this organ present from moment to moment. 



Further, as no analogous phenomenon is to be found 

 outside the animal kingdom, the physician would 

 doubtless be at a loss to understand the mechanism 

 of the ventricular contractions, namely, the centrifugal 

 impulse given by the organ at the moment of systole. 



Even physiologists must acquire some preliminary 

 knowledge, by means of vivisection, of the shape of 

 the heart and its peculiar movements before they can 

 understand the real significance of a cardiogram ; 

 but our eyes are hardly capable of following the 

 rapid and complicated variations presented by a 

 heart in motion, the shape of the various cavities 

 whether being filled or emptied, the moment of 

 distension of the blood-vessels of the heart, or the 

 contractions of the muscular fibres, etc. 



As soon as Ave had at command a method of chrono- 

 photography which faithfully interpreted the changes 

 in shape and position of moving bodies, we sought to 

 derive from tins method information supplemental to 

 thai furnished by the graphic method. The following 

 experiments were our first attempts in that direction. 



Photography of the Successive Phases of Cardiac 



