GERM GLANDS AND GERM CELLS OF FROG LARVAE 557 



edges, showing indications of atrophy and resorption. The 

 sucker-like tadpole mouth was beginning to show signs of trans- 

 formation to the typical frog mouth. 



Microscopic examination of the sectioned material revealed 

 little or no change in the germ cells and the germ glands of the 

 starved tadpoles, other than those already recorded for the earlier 

 series killed May 6, May 15 and May 25. The cells were still 

 in the primitive, sexually indifferent state, and presented no nu- 

 clear changes indicative of maturation. No division figures were 

 observed. The gonads were undeveloped though a few migrat- 

 ing mesenchyme cells were observed scattered through the glands 

 (% 7). 



As regards the control larvae, the number of germ cells had 

 greatly increased and most of the cells of the female animals 

 were in late synaptene or post-synaptene stages (fig. 8). 



The germ glands of the controls were in advanced develop- 

 mental stages (fig. 8). 



The sex of the larvae was now easily distinguishable. The 

 anlage of the females contained large cavities lined with endo- 

 thelium. The number of migrating mesenchyme cells from the 

 mesonephric tissue had greatly increased. The gross size of the 

 gland had greatly increased; the large size being due chiefly to 

 the connective tissue elements of the gland and not to any 

 marked increase in the number of germ cells. 



From June 1 on, the control animals began to metamorphose 

 rapidly, and by June 17, the change from the larval to the adult 

 state was complete in most of the larvae, except for a rudimentary 

 tail. 



The tail was completely resorbed in most of the animals by 

 June 22. Owing to the difficulty of keeping the young frogs, 

 and to the pressure of the other work, the control animals for the 

 starved larvae were killed June 29. 



The gonads of the young frogs had not, as yet, developed the 

 morphological characteristics of these organs in adults. This is 

 especially true of the male animals. In this sex, the transforma- 

 tion of the ribbon-like germinal mass lying on the ventral surface 

 of the mesonephros into the oval shaped testes does not occur 

 until several weeks after metamorphosis is completed. 



THE JOURNAL OK EXPERIMENTAL ZOOLOGY, Vol . 24, NO. ?, 



