376 INTERNAL SECRETION 



placenta. In so far as they illustrate the therapeutic uses of 

 placenta secretin, these experiments of Basch's are both important 

 and interesting, but they do not afford a satisfactory explanation 

 of the mechanism by which the impulse to secretion of 

 milk after parturition is supplied. If we assume that this 

 impulse is supplied by the placenta, we are faced with' the 

 further problem, namely, that during the entire course of its 

 development in pregnancy, this organ fails to excite the secretion 

 of milk in the^mammary glands; and that its activity in promoting 

 secretion is developed at the moment when its connection with 

 the uterine wall ceases. If the secretory hormone were elaborated 

 in the placenta, it would be active during pregnancy. This 

 physiological inconsistence is not explained by the assumption 

 (Keiffer, Basch), that the amount of secretion supplied by the 

 placenta to the blood stream is very much increased during labour. 



The secretion of the hyperplastic mammae is not difficult of 

 explanation, if viewed in the light of the theory laid down in 

 Part I. of this book. The growth of the gland is the expression of 

 an assimilatory increase of material with simultaneous inhibition 

 of disassimilatory decomposition. The growing gland produces 

 no secretion, or very little (colostrum). With the suppression of 

 the assimilatory hormone supplied by the foetus, that is to say, 

 at birth or by termination of the pregnancy during the second 

 half, disassimilatory decomposition, as expressed by the secretion, 

 is enabled to proceed unchecked. 



The mammary gland is an organ which is present in the 

 primitive genital trace of both sexes ; during intra-uterine existence 

 it undergoes a certain degree of development, and later assumes 

 the part of a secondary characteristic of the female sex, attaining 

 to further development under the influence of the ripening female 

 genital gland. The function of the mammary gland, so intimately 

 associated with the process of reproduction, does not become 

 apparent until after the formation (of the foetus from the fertilized 

 ovum, for the developing foetus supplies a hormone which pro- 

 motes hyperplasia of the glandular elements, and it is the 

 suppression of this hormone which permits the onset of the 

 secretory function. 



THE RESULTS OF CASTRATION. 



The operative removal of the sexual glands is followed by a 

 group of symptoms which, both in man and animals, has formed 

 a subject of exhaustive investigation. The results of castration 

 differ to a certain extent according to the age at which the opera- 

 tion is carried out. 



The castration of young males is one of the oldest forms of 

 operation, and one which is still in frequent practice in the East. 



