Physiology of the Heart. 9*7 



Studies in the Comparative Physiology of the 



Heart. 1 



By T. Wesley Mills. 

 RHYTHM AND INNERVATION OF HEART OF SEA TURTLE. 



This investigation was undertaken partly as a continua- 

 tion of previous work on the sea turtle, a short account of 

 which had already been published in the Journal of Physi- 

 ology, but chiefly as a continuation of my work on Chelonian 

 heart physiology in general. A paper of mine, on the ter- 

 rapin's heart, has recently appeared in Vol. VI, Nos. 4 and 

 5, of the journal referred to ; but the whole of my work on 

 the Chelonians is intended to furnish a systematic compari- 

 son from a physiological point of view of several of the 

 genera and species of the Chelonians. It is thought that no 

 such systematic comparison has ever before been attempted 

 for physiology, though it is constantly being done in mor- 

 phology. 



The investigation on the terrapin was carried on in the 

 Biological Laboratory at Baltimore ; those on the sea turtle, 

 alligator and fish, at the Marine Laboratory at Beaufort, 

 N". C. Only a very brief account of this work is furnished 

 here, the papers in extenso having been sent for publication 

 in the Journal of Physiology of Cambridge, England, in which 

 also due acknowledgement is made of my indebtedness to 

 the authorities and teachers of the Johns Hopkins Univer- 

 sity for facilitating these investigations. 



In all of them the direct method of observation has been 

 used and the heart has been experimented upon mostly in 

 situ. For electric stimulation, a Du Bois induction coil, fed 

 by one Daniell's cell has been used, except in the case of 

 one set of experiments on the alligator, in which a Bunsen's 

 cell was substituted. 



In order to insure the specimens of the sea turtle 

 being in the best possible condition, those not used at once 



1 Contributed by Prof. Mills, of McGill University, Montreal, to 

 John Hopkins University Circulars. 



1 



