TEMPERATURES IN TURTLES. 433 



varied hut little from that of the environment wherein the 

 limits did not exceed 4 degrees C. It is of interest that the 

 same author noted the observations of Valenciennes (7) which 

 \vrrr later substantiated by Sclater (8), that the female python 

 when coiled about the eggs during incubation, maintained a 

 body temperature considerably above that of the surrounding 

 air. Sclater found on comparing the body temperature of the 

 incubating ft -male with that of the male, that during the height 

 of incubation the difference was as much as 10 degrees C., and 

 tint -he was some 20 degrees C. above the surrounding air. 

 \Ylu-t h< T this marked increased in heat production was brought 

 about l.y luiirjng into play a thermal regulatory mechaniMii. 

 i.r was <lue io other causes was not stated and has not yet been 

 iie<|. Similar observations were reported in 1881 by Forlu-- 

 9 , with -oincwhat less conspicuous differences. The greatest 

 dili< "f tlu- air and the surface coils of the snake was about 



' <!' in the male, and about 9 degrees C., in the female. 



It wa> noted in this study that the female took no food and was 

 comparatively inactive for weeks before and during incubation. 



In 1903, Martin (io) working with the respiratory exchaiu 

 in Monotremea and Marsupials included some observations on 

 the blue-tongue lixards (Cyclodus gigas}. These, five in number, 

 In- carried t hi < nigh changes in temperatures varying from 5 to 

 .\n deg] , within a calorimeter. At room temperature they 



\\eiv comparatively active but became quite inactive at 5 

 ' >n warming they increased in activity up to until 

 about 30 d - and above this their activity diminished. The 



I'oily fluctuations accompanying these changes were noted. 

 Throughout the middle ranges (10-35 degrees C.) the body 

 1 1- m pi -ratine was a function of the environment but the CO 2 

 production \\a- fairly constant. At the extremes (below io and 

 above 35) as -hown in his plots, Fig. 3, sharp breaks occur, 

 \\ith approximation to Yan't Hoff's law. Notwithstanding that 

 IK- kept the animals in an environment of between ,v and 40 

 degrees < ., for over two hours he was unable to get their mean 

 temperature above 38.5. In their work on certain of the cold- 

 blooded animals Rogers and Lewis (io) followed the body 

 temperature lluctuations in only two representatives of the 

 \ertebrate-. the fishes (goldfish) and the amphibians (sala- 



