GERM GLANDS AND GERM CELLS OF FROG LARVAE 563 



serve them for microscopical examination. At the time of death, 

 they were small tadpoles 15 mm. in length, and showed no indica- 

 tions of limb development or other signs of somatic development. 



DISCUSSION 



The experiment quoted apparently justifies the conclusion that 

 total inanition not only prevents the formation of the germ an- 

 lage of Rana pipiens larvae, but inhibits the onset of maturation 

 processes and increase in number of the germ cells. 



It is an odd fact, but the germ cells of old larvae of a different 

 species of frog are apparently much less affected by total inmi- 

 tion. A series of year old Rana catesbiana tadpoles, measuring 

 75 mm. at the beginning of the experiment, was starved for five 

 months and ten days. The larvae received nothing to eat save 

 perhaps the microscopic organisms found in all tap water. Dur- 

 ing this interval, the broad tails of the larvae shrunk to less than 

 half their original width. The body musculature was partly 

 absorbed and all growth and development was inhibited. Mi- 

 croscopic examination of the gonads revealed no observable dif- 

 ferences between starved and control larvae. The large corpora 

 adiposa of the controls, however, was so shriveled in the starved 

 animals as to be almost unrecognizable; as this body is attached 

 to the gonads, it may be that the germ cells derived their 

 nourishment from it. 



In view of Mead's ('00) work with starfish, in which he ob- 

 served that sex is correlated with the attainment of a certain 

 size (50 mm.) in these animals, the results obtained for the 

 starved larvae of Rana pipiens are interesting. None of the small 

 unfed tadpoles differentiated sexually. In the controls, sexual 

 differentiation was first recognized with certainty when the tad- 

 poles averaged 30 mm. in length. Very probably sex is recog- 

 nizable earlier in this species when the animals are still smaller. 

 No examination to test this point was made. 



The observation that many of the germ cells of two unfed lar- 

 vae, starved from the time of their emergence from the egg cap- 

 sule (April 10) until July 8, were apparently entering early mat- 

 uration stages, despite the fact that the development of the 



