Function of Corpus Luteum 



443 



If a slightly larger part of the uterus is left back — perhaps 

 one-third or one-fourth its length — the full effects of this opera- 

 tion are not observed, although the life and function of the cor- 

 pus luteum is somewhat prolonged even under these conditions. 

 In different experiments the ovulation following an incomplete 

 extirpation occurred between a period of twenty-one and thirty- 

 two days following the preceding ovulation, but a delay in the 

 later ovulations was either absent or only very slight. A rela- 

 tively small part of the uterus can therefore, at least to a great 

 extent, take over the function of the whole uterus. The pro- 

 longation of the life of the corpus luteum which occurs even 

 under these conditions may again call forth a proliferation in 

 the mammary gland in some cases. However, there are certain 

 factors in the growth of the mammary gland which need still 

 further investigation. 



We believe that this method of prolonging the life and func- 

 tion of the corpus luteum will prove of value in the analysis of 

 the mechanism of the sexual cycle. 



Differences in the effect of hysterectomy in different species 

 depend presumably on differences in secondary factors; it is not 

 probable that in principle the effect of the uterus on the corpus 

 luteum differs in different species. 



222 (2182) 



The mechanism of the sexual cycle and the specificity of growth 



substances. 



By LEO LOEB (by invitation). 



[From the Department of Comparative Pathology, ^Yashi7lgtan 

 University, St. Louis, Mo.] 



The experimental analysis of the sexual cycle carried out par- 

 ticularly during the last fifteen years makes it possible to state 

 the main factors regulating its mechanism. While this analysis 

 rests largely on experiments and observations in rodents, and 

 especially in the guinea pig, yet in principle conditions seem to 

 be similar in all the mammals. 



