552 W. W. SWINGLE 



When compared with the control animals, the growth of the 

 starved series of animals was found to be inhibited, for the aver- 

 age length of the unfed larvae was but 13 mm., approximately 

 the same length as the tadpoles killed nine days before. No indi- 

 cations of limb development were observed. 



Microscopic examination "of the germ anlagen of the control 

 and the starved animals revealed rather striking differences. 

 The germ cells of the unfed tadpoles presented few developmental 

 changes from those of the larvae killed May 6. The yolk spher- 

 ules, present in the cytoplasm of the germ cells of the May 6 

 series, had disappeared. The number of germ cells appearing in 

 transverse sections of the gland had increased slightly, showing 

 that some multiplication of the germ cells had occurred. 



The structure of the germ anlage of the starved tadpoles had 

 undergone no observable changes and remained small clusters 

 of sexually undifferentiated germ cells (fig. 3). 



Contrasted with the undifferentiated character of the germ 

 glands of the unfed tadpoles, the gonads of the controls of this 

 series presented marked developmental changes (fig. 4). The 

 number of germ cells had greatly increased, there being many 

 more cells in the gonads of the control (transverse section) as 

 observed in the glands of the unfed tadpoles. This increase in 

 the number of germ cells had greatly augmented the size of the 

 glands, especially the length (transverse section). Many mesen- 

 chyme cells had proliferated into the glands forming a well de- 

 veloped secondary genital cavity. Sexual differentiation had 

 occurred and in both male and female gonads the germ cells 

 were partitioned off into nests or cysts by the migrating cells. 



The germ cells of the control larvae presented striking nuclear 

 changes, consisting in a rearrangement of the chromatin into the 

 configurations characteristic of presynaptic stages. This was 



Fig. 3 Gonad of tadpole starved thirty-six days. Series of May 15. A, peri- 

 toneal cell; B, mesenchyme cell; C, germ cell. X 800. Transverse section. 



Fig. 4 Gonad of control larva for animal shown in figure 3. Series of May 

 15. A, peritoneum; B, primary genital space fille 1 with embryonic connective 

 tissue; C, secondary genital space; D, mesenchyme cells. X 800. Transverse 

 section. 



