132 



CYCLIC CHANGES 



IV 



Fig. 92. Cyclic changes in the pregnant Lebistes female. 



wall and the wall of the yolk-sac. In addition to the intake 

 of oxygen and the loss of carbon dioxide there is also assi- 

 milation of water and of salts. The embryo is accordingly 

 heavier than the fertilised ovum. We do not yet know 

 whether interchange of organic substances occurs. While the 

 foetus is still developing, the follicle ruptures where the fol- 

 licle-stigma was located, so that the lumen of the follicle and 

 that of the ovary become connected. The young fishes leave 

 the follicle through this opening, the follicle remaining 

 behind as calyx. Then, for some time, the granulosa secretes 

 an embryotrophe, which nourishes the young fishes in the 

 lumen of the ovary. During this brief period, therefore, the 

 calyx nutricius, in its secretion of an embryotrophe, behaves 

 as the calyx nutricius in Zoarces. 



After parturition, these calyces involute; they persist until 

 half-way through the next pregnancy, after which they 

 appear only as scars. Pre-ovulation corpora lutea are found 

 in Lebistes, as in Zoarces, during the entire course of preg- 

 nancy, in at least 4 generations, and preliminary, functional 

 and regression-stages exist side by side. The intensive lutein- 

 isation and copious blood supply of these corporea lutea 

 point to considerable activity, of the same nature as in 

 Zoarces, which in virgin females runs parallel with their 



