THE RELATION OF BODY TO ENVIRONMENTAL 



TEMPERATURES IN TURTLES, CPIRYSEMYS 



MARGIN AT A BELLI (GRAY) AND 



CHELYDRA SERPENTINA 



(LINN.). 



FRANCIS MARSH BALDWIN*. 

 IOWA STATE COLLEGE, AMES. 



Although a considerable number of workers have recorded 

 their observations on the relation of body temperature to that 

 of the environment of different so-called cold-blooded animals, 

 only a comparatively few of these refer especially to the reptiles, 

 as a group, or to the turtles in particular. With but the excep- 

 tions indicated below, all the records from the early \vorkers 

 were based upon a limited number of individuals taken for the 

 most part at random within narrow limits of normal but slight 

 environmental changes. It has thus become quite generally 

 assumed by biologists that turtles together with other cold- 

 blooded animals approximate the temperature of their sur- 

 roundings. In view of the fact that turtles as a representative 

 group of the reptiles have an unique phylogenetic position, 

 spanning the gap as it were between the warm-blooded birds 

 on the one hand, and the cold-blooded amphibians on the other, 

 it was thought that a study of their body-temperature changes 

 when followed through high and low critical temperatures as well 

 as the ordinary non-critical ranges, might yield interesting data. 



The earliest observation of the body temperature in turtles is 

 probably recorded by Walbaum (i), in 1782. He found the 

 temperatures differed only one or two degrees from that of its 

 environment and fluctuated with it. Following Walbaum a 

 considerable number of workers made similar observations during 

 the first half of the nineteenth century. Milne- Ed wards (2) in 

 1863, after giving a critical review of the work done on these 

 forms by Czermach (3), Murray (4), Tiedemann (5), Davy, J. 

 (6), and Valenciennes (7), concluded that the body temperatures 



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