THE FUNCTION OF (ESTRIN . 125 



without those of complete oestrus. Even in rodents, oestrus 

 induced in the ovariectomized animal is incomplete, in the 

 experience of most workers, in that copulation does not take 

 place. Allen and his collaborators (24) report that seven out 

 of eleven rats copulated at induced oestrus, but Parkes, Fielding 

 and Brambell (510J found that of 92 induced oestrous periods in 

 mated ovariectomized mice only seven w^ere accompanied 

 by copulation. Of these seven, three occurred in mice 

 which were found to have regenerated ovarian tissue. Copula- 

 tion takes place freely during induced oestrus in ovariectomized 

 mice with regenerated ovarian tissue, and during oestrus 

 induced in the normal animal. In the writer's experience, also, 

 ovariectomized rabbits, receiving heavy injections of oestrin, do 

 not show the tail erection reflex, and will not copulate. Lacas- 

 sagne and Gricouroff (338), however, state that oestrin will 

 produce copulation in the ovariectomized rabbit. So far as 

 these results go, copulation is clearly not usual at induced 

 oestrus in the ovariectomized mouse, and the missing factor may 

 well be that responsible for the initial development of the 

 accessory organs. 



On this view, the ovary probably controls the initial develop- 

 ment of the accessory organs by means of some basic internal 

 secretion analogous to that produced by the interstitial tissue 

 of the testis. To this constant endocrine activity, the cyclically 

 active hormones of the oestrous cycle are added at puberty. 

 The irregular occurrence of ovarian interstitial tissue and its late 

 appearance even where present, make it highly improbable 

 that it can elaborate this basic ovarian secretion in a manner 

 analogous with the endocrine activity of the interstitial tissue of 

 the testis. Some such assumption is, however, implied by the 

 use of the term puberty gland ' by Steinach (590) and others to 

 denote both ovarian and testicular interstitial tissue. 



{e) (ESTRIN AND THE CHANGES OF THE 

 POST-OVULATION PHASE 



If the changes of the whole cycle are under the control of 

 oestrin, obviously the continuous injection of oestrin ought not 

 to result in the prolongation of oestrous symptoms, but in the 



