DESCRIPTION OF THE APPARATUS 



7S) 



In our attempts to represent, by ehronophotographic 

 means, the various changes in shape and appearance of 

 an animal's heart, as occurring in the auricles and 

 ventricles, we met this difficulty in its extreme form, 

 since the red colour of the muscles and of the blood 

 made no impression on the photographic plate. 



Fig. 53.— Extent of the movements of tho le^-s obtained by Messrs. Demeny and 

 Quenu iu a dark iooui. 



By painting the surface of the heart with a solution 

 of Chinese white we have found it possible to take a 

 photograph of it, and we have obtained excellent 

 results with very short exposures. We need say but 

 little about the best conditions for illuminating: the 

 contour of objects. In this respect photographers 



