PHYSIOLOGY, CHEMISTRY AND PATHOLOGY 565 



Artificial Production of Corpora Lutea 



In rabbits ovulation and formation of corpora lutea do not occur 

 spontaneously, but need the additional stimulus of copulation. Ancel 

 and Bouin (g) (1909) discovered that, if the rupture of the follicles be 

 brought about artificially, either by copulation with a male whose vasa 

 deferentia had been ligated, or by mechanical means, it was followed by 

 the formation of corpora lutea and also by a growth of the mammary 

 glands. 



The experiments of O'Donoghue (Y) confirm in the main those of the 

 French writers. Rabbits were taken on the third and fourth days of 

 "heat" and the ripe follicles in their ovaries were burst mechanically. 

 They were allowed to heal up and the animals were killed and examined 

 at varying periods after the operation. But O'Donoghue found that the/ 

 rupture of the follicles was not invariably followed by the formation 

 of corpora lutea, and when corpora lutea were not produced, there was 

 no growth of the mammary glands (vide infra). 



Artificial Production of Deciduomata 



As we have seen, Frankel (&) and others showed that the corpus luteum 

 produces some change in the uterine mucosa which helps in the fixation 

 of the fetus during the earlier period of pregnancy. It remained for 

 Loeb (1917) to reveal precisely what these changes really consist in. It 

 occurred to this observer that the influence of the yellow body could be 

 cleared up only by performing a series of experiments, in .which the 

 changes in the uterus could be studied directly, without the interference 

 of a fertilized ovum. Pregnancy was, therefore, excluded by tying the 

 Fallopian tubes soon after copulation, or by using guinea pigs in which 

 heat had been observed. In the normal guinea pig a spontaneous ovula- 

 tion takes place at the time of heat in almost all cases. Loeb succeeded, 

 furthermore, in substituting ordinary foreign bodies and other mechanical 

 stimuli for the action of the ovum. It was found that, if such me- 

 chanical stimuli are applied to a uterine mucosa which has been previously 

 sensitized by the internal secretion of the corpus luteum, a maternal pla- 

 centa is produced at the place of stimulation. The mechanical stimulus 

 replaces the ovum in these experiments. 



Loeb observed that, even without the presence of a definite and well 

 defined mechanical stimulus, the mucous membrane of the uterus shows 

 some slight overgrowth, due to the secretion of the yellow body. He 

 assumes that the stimuli occurring in normal life produce these changes 

 in a sensitized uterus. In Dasyurus viverrinus, a marsupial studied by 



