2IO THEO. C. BURNETT. 



mer et le milieu vital du Vertebre, il y a physiologiquement 

 identite." 



Summary. 

 i. Strips of the ventricle of the turtle's heart will live as long 

 in isotonic sea water as in Ringer's solution. 



2. After "sodium chloride arrest," strips of ventricle will re- 

 cover as well in isotonic sea water as in Ringer's solution. 



3. The whole heart will beat as long in isotonic sea water as 

 in Ringer's solution. 



This problem was suggested to me by Professor Loeb, and I 

 have to thank him for many helpful hints. 



Note. — At the time these experiments were begun and the 

 paper was in preparation, I was ignorant of the work of Mayer * 

 on the embryo heart of the loggerhead turtle, which should be 

 referred to. 



1 Mayer, Alfred G. , "Rhythmical Pulsations in Scyphomedusae," Carnegie Institu- 

 tion of Washington, Publication 47, 1906. 



