SEXUAL CYCLE OF RHODEUS AMARUS $ 



125 



Rhoc'9U5 oviposition 



hypoph. 

 Corp. lut. 



ovipositor^ 



day 1st 2nd 3rd 4 th 



Rhodeus egg restitution 



Corp. lut 

 montfis 



Fig. 83. Relation between the rhythm of ovipositor growth, the forma- 

 tion of corpora lutea and the hypophysis in the female bitterling. 



The rhythm in the growth of the ovipositor has its con- 

 comitant in a similar rhythm in the ovary and in the hypo- 

 physis. The curves in Fig. 83A during estrus only show the 

 maxima; in reality they run up and down. In these months 

 we find, in addition to animals with numerous corpora 

 lutea, others without any corpora lutea, and the length of 

 the ovipositor varies correspondingly. In accordance with 

 this, Van Iersel (vide p. 70) found, during this time, in 

 addition to hypophyses with intensive basophilia throughout 

 the whole of the lobus anterior, others possessing only small 

 basophil islands, such as we find in anestrus. 



A day before oviposition the follicles ovulate; we then 

 find calyces in the wall of the ovary, and lying loose in 

 front of the mouth of the oviduct. Oviposition lasts only 

 one day, after which there is a pause of from 6 to 8 days 

 before the next oviposition. Even before the gonad is deprived 

 of its stock of ova owing to oviposition and copious pro- 

 duction of corpora lutea, and already during estrus, restitu- 

 tion of ova commences. The curve of the small oocytes 

 reaches its lowest point in May, rising rapidly directly after. 

 Our experiments with hormones described on p. 52 and 53, 

 in which there was no oviposition, but considerable produc- 

 tion and consumption of corpora lutea, also show the same 



