564 w. W. SWINGLE 



soma and germ anlage had been completely inhibited, indicates 

 that possibly the germ cells possess certain capacities for physi- 

 ological recuperation from nutritional disturbances, independent 

 of the soma. 



It is more probable, however, that the two larvae received 

 slightly more food than the other animals of the culture, and 

 that their germ cells responded immediately by developmental 

 changes to the stimulus of nourishment. The odd fact that the 

 germ gland itself failed to respond is more readily understood 

 when one takes into consideration the work of Nussbaum ('06). 

 It was mentioned in the review of the literature early in this 

 paper, that Nussbaum reported great shrinkage of the gonads of 

 starved frogs, the glands shrinking to one-third their original size, 

 but that when nourishment was given the annuals, the gonads 

 increased in size rapidly, whereas the remainder of the body 

 remained emaciated. In view of these results, it appears prob- 

 able that the germ cells of the two larvae in my cultures which 

 were so far along in development, responded more readily to the 

 slight .food stimulus than the soma cells of the gonads; very 

 likely the gonads would also have developed somewhat had the 

 nourishment been greater. 



SUMMARY AND CONCLUSION 



1. Total starvation inhibits indefinitely the growth and the 

 metamorphosis of larval frogs. 



2. It prevents the development of the germ glands and delays 

 any increase in the number of germ cells, interstitial cells and 

 other tissue elements in the gonads. 



3. Starvation greatly retards the normal cycle of development 

 of the germ cells. 



4. It prevents the onset of sexual differentiation. 



I take this opportunity of acknowledging my indebtedness to 

 Dr. B. M. Allen of the University of Kansas for suggesting this 

 problem, and for the interest he has shown in the work. 



