PHYSIOLOGY, CHEMISTRY AKD PATHOLOGY 563 



rant publication. Since then, however, Marshall and Jolly (a) have re- 

 ported that "heat," or a transient condition resembling it, can be pro- 

 duced by the injection of extracts of estrous ovaries. It is possible that 

 in some of these experiments the extracted ovaries contained corpora 

 lutea and that the effects observed (chiefly consisting of hyperemia of 

 the external genitals) were due to active substances derived from the yel- 

 low bodies. Recent experiments by Aschner (&), Okintschitz, and others 

 have confirmed the fact that injection of extracts of ovary cause hyperemia 

 and swelling of the reproductive organs. It is not clear from these 

 experiments how far the results are due to corpus luteum and how far to 

 other parts of the ovary. The changes induced do not seem to be true 

 cyclic growth processes, but simply transient circulatory effects. Pearl 

 and Surface have recently shown that the desiccated fat free substance of 

 the corpus luteum of the cow, when injected in suspension in proper 

 dosage into an actively laying fowl, immediately inhibits ovulation. The 

 duration of this effect varies with different birds, from a few days up to 

 two or three weeks. After the bird begins ovulating again the laying 

 goes on unimpaired. The same effect is produced by the injection of 

 extracts of the lutear substance, either intravenously or intra-abdominally. 

 The active substance producing the inhibition is inactivated by boil- 

 ing. 



The whole subject of the physiological effects induced by extracts of 

 ovary, with and without corpora lutea and both with and without inter- 

 stitial cells, demands renewed careful investigation. In such investigation 

 particular attention should be paid to the mode of preparation of the 

 extracts and the chemical nature of the substances contained in them. 



Extirpation of the Corpus Luteum 



Prenant (1898) was apparently the first to suggest that the corpus 

 luteum furnishes an internal secretion. He thought that the body in- 

 fluenced general metabolism and prevented ovulation during pregnancy or 

 between the estrous periods. This theory was supported by Regaud and 

 Policard (&) (1901), Beard (1897), Sandes (1903), and others, and seems 

 to be firmly established by the more recent investigations of Loeb (n) 

 (1911). In sixty-six guinea pigs it was ascertained that spontaneous ovu- 

 lation rarely occurs within sixteen to eighteen days after a preceding ovu- 

 lation. In twenty-five animals all the yellow bodies were successfully 

 removed, and in 92 per cent of these all ovulated within twelve to sixteen 

 and one-half days after coitus, showing a marked shortening of the in- 

 terval between ovulations. Pregnancy per se will not inhibit ovulation. 



Confirmation of these results is afforded by the experiments of Pearl 



