566 SWALE VINCENT 



Hill and O'Oonoghue, in which the corpus luteum is well developed 

 and persistent in the non-pregnant animal, the enlargement of the uterine 

 mucosa is specially marked. It may be, as suggested to me by Professor 

 O'Donoghue, that the effect of a mechanical stimulus is largely to 

 localize the overgrowth and thus help in the development of definite 

 deciduomata. 



There is a definite parallelism between the development of the corpus 

 luteum and the cyclic changes in the uterine mucosa. By experimental 

 means a much larger quantity of maternal placenta may be produced than 

 under normal conditions of life. 



The results of Loeb have been confirmed by Ancel and Bouin, Biedl, 

 and E. T. Frank. 



The secretion of corpus luteum, then, sensitizes the uterine mucosa 

 and makes it capable of reacting to mechanical stimulation. There is a 

 relation between the quantity of the secretion on the part of the yellow 

 body and the degree of response which can be obtained by a mechanical 

 stimulation. The response is only obtained when sufficient secretion to 

 sensitize the mucosa has been poured out. If the stimulus be applied 

 when the body is just beginning to secrete, little effect may be produced. 

 But if the application be made later, when the uterine wall has become 

 completely sensitized, the secretion of the substance goes on for a few 

 more days and increases the reaction. The ovum becomes attached at 

 about the time when the greatest sensitization of the mucosa has been 

 obtained (Loeb). 



Several other interesting facts were brought to light by Loeb's investi- 

 gations. The substance secreted by the corpus luteum and which sensi- 

 tizes the uterine mucosa is not specific, that is to say, the substance of 

 one individual will cause growth in the sensitized uterus of a second 

 individual of the same species. The effect, however, is less pronounced 

 than in the organism to which it belonged. This difference is supposed 

 to be due to the presence of "homoiotoxins" in the second individual. The 

 sensitizing substance produced by the corpus luteum gives rise to special 

 and characteristic reactions in the different species. The experimental 

 deciduomata in any species have the structure of the maternal placenta 

 in pregnancy. In some animals (rabbit, guinea pig) the effects are con- 

 fined to the uterus, while in the human subject deciduomata can be 

 produced in the Fallopian tubes in cases of tubal pregnancy. Loeb sug- 

 gests that the readiness with which extra-uterine pregnancy develops in 

 different species depends, in part at least, upon the readiness with which 

 the stroma of the host responds with the production of a decidua favor- 

 able for the development of the embryo. 



Deciduomata become necrotic within twenty days, and the cyclic 

 proliferation of the mucosa lasts only a few days. Extirpation of the 

 corpora lutea prevents the deciduomata from reaching full size and 



