THE 



CANADIAN RECORD 



OF SCIENCE. 



VOL. II. JULY, 1886. NO. 3. 



Studies in the Comparative Physiology of the i.***-****^*** 



Heart. J&**?** 



By T. Wesley Mills. 

 (Concluded.) 



ON THE PHYSIOLOGY OF THE HEART OP THE ALLIGATOR. 



The animals experimented upon belonged to the species 

 Alligator Mississippiensis. The heart in the Crocodilia, with 

 its two auricles and paired ventricles, though showing much 

 resemblance to lower forms and retaining the pulsatile sinus 

 venosus, both in its general appearance and in its action, 

 approximates sufficiently to that of the higher vertebrates to 

 suggest on superficial examination the heart of a mammal 

 or bird (with slower action) . The blood, too, is more highly 

 oxidized than in the Chelonians, so that altogether the cir- 

 culatory system shows physiological as well as anatomical 

 advance. With the exception of G-askell's short paper on the 

 crocodile, (Journal of Physioloqy, Yol. V., No. I), nothing has 



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