84 INTERNAL SECRETION 



tested medicinally there is great need for more uniform methods 

 in the preparation of extracts. The only definite physiological 

 effects alleged to be produced by luteal extracts are changes 

 in the contractions of the uterus and smooth muscle of other 

 regions, and an effect on the flow of milk. For example, 

 Itagaki states that luteal extracts usually increase the tone 

 of the surviving uterus of the rat, rabbit, dog, and guinea- 

 pig, though occasionally the result is in the opposite direction. 

 He believes that the different results are due to the effects 

 of two separate principles, having antagonistic actions on the 

 uterus. The inhibitory substance is soluble in alcohol, while 

 the augmentory principle is insoluble in alcohol, but soluble 

 in water. The evidence for the existence of two opposing 

 active principles cannot be regarded as very convincing. 

 Chauffard urges that the yellow body is a centre for the pro- 

 duction of cholesterin. He points out that this substance 

 is present in the corpus luteum during pregnancy, and that 

 cholesterinaemia occurs at this time. But the corpus luteum 

 is not the only centre for the production of cholesterin. Ex- 

 tracts of the corpus luteum are said to stimulate the contrac- 

 tions of the vas deferens and the seminal vesicles, but this must 

 be an accidental and not a specific reaction. One cannot 

 avoid the suspicion that in such experiments no adequate 

 regard is paid to control experiments carried out with extracts 

 from other organs and tissues. 



Ott and Scott (1910) reported that extracts of pituitary, 

 thymus, pineal, and corpus luteum act as galactagogues. 

 So far as the pituitary and luteal extracts are concerned, the 

 result was confirmed by Schafer and MacKenzie. It is now 

 generally considered that galactagogue principles can be 

 extracted from pituitary, corpus luteum, pineal, mammary 

 gland, and the involuting uterus. It is very probable that 

 the list will be extended, but there is little reason to regard all 

 these organs as furnishing " hormones " for the purpose of 

 stimulating milk secretion. 



Corpus luteum extracts are now frequently employed by 

 medical men in cases of deficient milk secretion in women. 



Attempts to replace the internal secretion of the corpus 

 luteum by means of injection of extracts have not given very 

 satisfactory results. Several years ago the present writer, 

 in conjunction with Dr. F. H. A. Marshall, performed a s< -ri< > 



