AGE, GROWTH, AND DEATH 



There are animals, like the frogs and salamanders, 

 which will live at a very considerable range of tem- 

 perature and thrive, apparently. No ultimate injury 

 is done to them by a change of their bodily tempera- 



FIG. 26. FOUR TADPOLES OF THE EUROPEAN 

 FROG Kana fusea. After Oskar Hertwig. The 

 four animals are all of the same age (three days) and 

 raised from the same batch of eggs, but have been 

 kept at different temperatures. 



A at 11.5 centigrade. B at 15.0 centigrade 



C " 20.0 " D " 24.0 " 



ture. Here we have four young tadpoles, (Fig. 26), 

 all of which are exactly three days old. The first of 

 these has been kept at a temperature not much above 

 freezing; the fourth at a temperature of about twenty- 



