INTERNAL SECRETION OF CORPUS LUTEUM 179 



suppressed in some animals for months after the end of treat- 

 ment. Clearly no physiological action comparable with the 

 normal activity of the corpus luteum can have caused such a 

 prolonged inhibitory effect. Haberlandt (259), however, has 

 more recently described oestrus-inhibiting effects from the 

 inj-ection of extracts of both ovary and placenta. In the rabbit, 

 the inhibition and recovery is described by him as consisting of 

 three stages; (a) complete inhibition of both ovulation and 

 mating instincts, (b) inhibition of ovulation, though copulation 

 will take place, (r) restoration of full ovulation and mating 

 instinct. Since a rabbit in good condition will copulate during 

 pseudo-pregnancy and pregnancy, one would imagine that 

 toxic effects also influenced these experiments. The neces- 

 sity for considering the possible toxicity of tissue extracts 

 has been emphasized by Kohler (334), and by Herrmann and 

 Stein (295), who obtained inhibition of oestrus by the injection 

 of irritant organic substances. 



Loewe (417) has reported the inhibition of cestrus in the 

 mouse by injection of a commercial extract of corpus luteum. 

 Quite recently various workers have concentrated on the pre- 

 paration of corpus luteum extracts capable of causing the 

 suppression of oestrus in the normal animal. Papanicolaou 

 (487 j injected lipoid extracts into the guinea-pig and brought 

 about the suppression of oestrus for a considerable period. 

 No method of preparation, however, was given by this author. 

 Johnston and Gould (316) were unable to inhibit the action of 

 oestrus-producing extracts by the simultaneous injection of 

 extracts of corpus luteum. On the other hand, Parkes and Bel- 

 lerby (507) inhibited oestrus in the unmated mouse by the injec- 

 tion of extracts of corpus luteum made with fat solvents. 

 Corpora lutea of the cow were dissected and all hollow specimens 

 rejected. The tissue of the solid corpora lutea was then minced 

 and ground up with anhydrous sodium sulphate. The mixture 

 was extracted with ether tw^o or three times in the cold, the 

 ether extracts evaporated down to small bulk, and acetone added 

 to precipitate the phosphatides. The acetone extract, when 

 evaporated down, gave a brownish oil which, emulsified with 

 J ^0 'Jodium bicarbonate and injected subcutaneously, was found 

 to be active in inhibiting oestrus. Large amounts of this oil had 



