50 HELEN DEAN KING. 



in the toad tadpole as it is in the Mexican axolotl according to 

 the observations of Shufeldt (12). The mortality in this lot was 

 very low, only 18 individuals having died at the time the record 

 was made. 



Lot B. — The tadpoles fed on wheat were, as a whole, con- 

 siderably smaller than those fed on meat, and they were more 

 uniform in size, the greatest number having a length of about 22 

 mm. By June 7, three individuals in this lot had begun their 

 metamorphosis, and 38 individuals had died. 



Lot C. — The smallest and least developed tadpoles were those 

 that were fed on a mixed diet. The greatest extremes in size 

 were also found in this lot, the body length varying from 10-21 

 mm. in different cases. In many individuals the hind legs were 

 only just visible, and in the largest individuals they were poorly 

 developed as compared with those of the individuals in other lots. 

 The mortality in this lot was very great, 97 individuals having 

 died by June 7. 



Lot D. — The great majority of the tadpoles fed on the yolk 

 of egg were intermediate in size between those fed on meat and 

 those that had received a purely vegetable diet, the average length 

 of these tadpoles being 22-24 mm. The individuals in this lot 

 had developed much more rapidly than those in any of the other 

 lots. By the seventh of June, 8 individuals had begun meta- 

 morphosis and many more were on the point of doing so. The 

 mortality in this lot also was very great as 63 individuals had 

 died. 



The differences between the individuals in the various lots of 

 Series II. were of the same character and as strongly marked as 

 were those in Series I. The death rate in Series II. was practi- 

 cally the same as in Series I.; the fewest deaths occurring among 

 the tadpoles that were fed on meat and on cereal, the greatest 

 number among those that were nourished on a mixed diet and 

 on the yolk of egg. 



Although the tadpoles began to undergo their metamorphosis 

 during the first week in June, the experiments were continued 

 until the middle of July as there was a considerable variation in 

 the rate of development among the tadpoles of the same lot. On 

 July 13, all of the tadpoles still living were fixed in corrosive- 



