42 E. R. HOSKINS AND M. M. HOSKINS 



rapidly than the controls, the ovaries were actually much larger, 

 but relatively smaller, than those of the 1917 larvae of a corre- 

 sponding stage, and their oocytes were smaller (60 n, fig. 98). 

 As figure 99 shows, the defective thyroidless larvae which grew 

 ver}'- slowly, developed ovaries actually smaller than those of 

 the larger and younger thyroidless larvae of 1918, and the oocytes 

 in these small ovaries were larger (130 m) than those of the others. 

 Figure 100 shows the ovary of a large thyroidless larva of the 

 age of the small thyroidless specimen of figure 99, and of nearly 

 the same size as that from which the ovary shown in figure 98 

 was taken. In the ovary of figure 100 the oocytes are numerous 

 and large (180 m)- Figure 101 shows the ovary of a large and 

 thyroidless larva of 1917. The oocytes are fewer but larger 

 (200 m) than those in figure 100. In figure 102, the ovary of 

 a still older thyroidless larva of 1917, the oocytes are 250 n in 

 diameter. During the second season the ovary and oocytes 

 again increased in size (fig. 103, oocytes 300 n). The animal 

 from which the ovary in figure 103 was taken was about the 

 same size as the animal whose ovary is shown in figure 100, but 

 five times as old. The latter specimen was about the same size 

 as the one whose ovary is shown in figure 98, but three times as 

 old. The animal referred to for figure 100, on the other hand, 

 was about the same size as that from which figure 101 was drawn, 

 but was only one-fourth as old. 



It will be seen that from the animals in our experiments one 

 can deduce no general law governing the development of the 

 ovary, either in size or dift'erentiation of the cells. There is 

 some correlation between the rate of development of the ovary 

 and the rate of growth of the body, but none between the size 

 of the ovary and that of the body, except in a general way. 

 There is no correlation between the stage of differentiation seen 

 within the ovary and its size or its change from the very flat 

 to the oval shape. In general one may say that when the larvae 

 grow slowly the relative rate of differentiation in the ovaries is 

 increased. When they grow rapidly the relative rate of differ- 

 entiation is decreased, but the difference between these rates 

 of ovarian differentiation is not proportional to the differences 

 in the rate of growth of the body as a whole. 



