252 



H. C. VAN DER HEYDE. 



The figures for the total nitrogen are graphically represented 

 in Fig. i. 



It is clear that temperature has in reality a tremendous in- 

 fluence on the frog's catabolism. From o till about 20 this 

 increase is only relatively slight. After 20 however the curve 

 rises almost vertically. When we compare our curve with that 



da 



j-Iotf 



1C 



11 



em. 



p 



FIG. i. The influence of temperature on the total nitrogen excretion. 



given by Lusk 10 after the figures of H. Schultze, we notice a 

 striking similarity between the two curves. It is clear moreover 

 that this fact has a great biological importance. The frog in 

 his hibernating stage at 4 in the mud can not have the intensive 

 metabolism which the frog in midsummer "as he sits on the 



10 Graham Lusk, "The Elements of the Science of Nutrition, "3d edition, W. B. 

 Saunders Co., Philadelphia and London, p. 115. 



