Adaptation to Environment 335 



pigment and trimethylamine at 35 . Davenport and 

 Castle 1 found that tadpoles of a frog kept at 15 went 

 into heat rigour at 40.3 C, while those kept for twenty- 

 eight days at 25 were not affected by this temperature 

 but went into heat rigour at 43.5°. When the latter 

 tadpoles were put back for seventeen days to a tem- 

 perature of 1 5 they had lost their resistance to high 

 temperature partially, but not completely, since they 

 went into heat rigour at 41. 6°. The authors suggest 

 that this adaptation to a higher temperature is due to 

 a loss of water on the part of protoplasm, whereby 

 the latter becomes more resistant to an increase in 

 temperature. This idea was put to a test by Kryz 2 , 

 who found that the coagulation temperature of their 

 muscle plasm is not altered by keeping cold-blooded 

 animals at different temperatures. 



Loeb and Wasteneys 3 found that Fundulus taken 

 from a low temperature of io° C. die in less than two 

 hours when suddenly transferred to sea water of 29 C. ; 

 and in a few minutes if suddenly transferred to a tem- 

 perature of 35 C. If, however, the fish were trans- 

 ferred to a temperature of 27 C. for forty hours they 

 could live indefinitely in sea water of 35 . By exposing 

 the fish each day two hours to a gradually rising tem- 



1 Davenport, C. B., and Castle, W. E., Arch. f. Entwcklngsmech., 

 1896, ii., 227. 



a Kryz, F., Arch.f. Entwcklngsmech., 1907, xxiii., 560. 



* Loeb, J., and Wasteneys, H., Jour. Exper. Zobl., 1912, xii., 543. 



