ISOLATION OF SEXUAL HORMONES 323 



papers of Fraenkel (1914, p. 692), Foges (1914, pp. 401, 407), 

 and Blair Bell (1920) may be referred to. Most authorities 

 claim to have observed specific effects from extracts of corpus 

 luteum, but the results seem to be contradictory. This we 

 can easily understand, since the effects, as explained above, 

 must vary according to the mode of preparation. 



As to the chemical isolation and definition of the specific 

 sexual hormones the experiments of Fellner and of Herrmann 

 are of an especial interest. These experiments will be dealt 

 with below. 



Iscovesco (quoted from Herrmann and Stein, 19 16) first drew 

 attention to the action of lipoid-containing extracts of 

 endocrine organs. He succeeded in producing a very marked 

 increase of the volume of the uterus by injecting an extract 

 prepared from the ovary by treating it with alcohol and then 

 desiccating the alcoholic extract and treating with acetone, 

 ether and chloroform. This was the method followed by 

 Fellner and Herrmann. 



Fellner (1913) worked with extracts of placenta, of ovaries 

 of pregnant animals containing corpora lutea, and of ovaries 

 of non-pregnant animals. He used for extraction a solution of 

 sodium chloride, alcohol and ether. He stated that injection 

 of extracts from pregnant animals caused in rabbits an hyper- 

 aemia and a thickening of the muscle layer of the uterus. 

 The epithehum thickened and the number of uterine glands 

 increased. There was an increased growth of the mammary 

 glands and of the nipples ; this phenomenon could be observed 

 even in injected male animals. On the contrary, extracts of 

 ovaries of non-pregnant animals had no effect. But ex- 

 tracts of testicle and of thymus had an effect similar to that 

 of organs of pregnant animals. Extracts of the brain were 

 without any effect. Fellner thinks that the specific substance 

 which causes the above-mentioned effects is possibly a lipoid 

 present in the corpus luteum in greater quantity than in other 

 organs. In recent papers Fellner (1917, 1920) puts forward 

 the view that the hpoid which he isolated from the corpus 

 luteum is really the specific sexual hormone or possibly one 

 of the sexual hormones secreted by this organ. 



Of great interest are the later experiments of Fellner, in which 

 he investigated the question as to whether the same substance 

 is present also in the interstitial cells of the ovary. He prepared 



