THE (ESTRUS-PRODUCING HORMONE 97 



{420), and cocaine also produce no effects. Gsell-Busse (252) 

 has recently reported that commercial sodium taurocholate 

 may have an oestrus-producing action. Very recently, how- 

 ever, it has become clear that vaginal cornilication may be 

 produced under other conditions than oestrus. Evans (183), for 

 instance, has shown that vitamin A deficiency, which, according 

 to Wolbach and Howe (643), causes cornilication of all mucous 

 surfaces in the body, results in cornilication of the vaginal 

 mucosa, even in the ovariectomized animal. Thus under 

 certain conditions, cornilication of the vagina is not entirely 

 specific for oestrus, and it is evident, therefore, that while the 

 reaction may be an adequate test in the assay of preparations 

 known to contain the oestrous hormone, new qualitative work 

 must be confirmed by the investigation of every possible crite- 

 rion of oestrus. The uterine reaction, for instance, may be studied 

 in confirmation of the vaginal test, although the difference in 

 threshold value mentioned above complicates this method. 

 The necessity for autopsy at every test is also a disadvantage. 

 The ferret, which has a vaginal reaction at oestrus not connected 

 with cornification, might be used for confirming the vaginal 

 diagnosis on rats and mice in new qualitative work, but the 

 inconvenience of the ferret for laboratory purposes counter- 

 balances the advantage of the external sign of oestrus. 



The immature animal. The injection of oestrin into the im- 

 mature animal brings about the appearance of precocious 

 oestrous symptoms, including opening of the vaginal orifice, and 

 where such symptoms may be detected in the intact animal, as 

 in the rat and mouse, this is a fairly convenient test for oestrus- 

 producing activity. It suffers, however, from two disadvantages 

 (a) the possibility of spontaneous ovarian activity, or of 

 anterior pituitary effects (see p. 165) and (h) the difficulty of 

 using such a test in the standardization of oestrin. 



Other criteria. An entirely different method of assaying 

 oestrous activity has been put forward by Frank and his co- 

 workers (222), by Seckinger (555) and by Brouha and Simonnet 

 (103), who have suggested that the effect of the oestrous hormone 

 on the spontaneous contractions of the uterus (see p. 203) could 

 be used as a criterion. Such a proceeding, however, has obvious 

 disadvantages. Blotevogel and his co-workers (71-74) have 



P.S.O, G 



