HORMONES AND THE MAMIVLE 93 



powerful augmentative influence on mammary secretion Effect of 

 in the lactating animal. This has been confirmed by JjfEjJJjJJ^ 

 Schafer and Mackenzie 1 and others. There has, however, excretion 

 been much discussion whether the extract produces this uSStfon. 

 effect by its well-known action on all involuntary muscle 

 an expressor effect, in fact or whether there is a 

 selective action on the mammary epithelium ; possibly 

 both factors are brought into play. 



I have recently carried out experiments, in which Effect of 

 injections of anterior lobe extract and infundibulin have j^jJJ^^on 

 been made into adult virgin and into non-pregnant the inactive 

 parous guinea-pigs, in order to test the effect of these m 

 extracts on the mammary glands in circumstances which 

 would avoid the possibility and consequent confusion 

 of an expressor action. In these experiments portions 

 of the mammae were first removed as controls, and 

 subsequently the animals received many injections of 

 the extracts mentioned. In no case was any histological 

 difference found in the mammary gland before and after 

 the injections. 2 



The thyroid and the mammae. Very little Thyroid- 

 experimental work has been recorded in this connexion. notSferfere 



In my own experiments it was noted that in one cat from with 

 which the thyroid had been removed during pregnancy during 

 suckling occurred after the birth of the kittens. This lactation - 

 showed that, like the removal of ovaries, thyroidectomy 

 does not interfere with the milk-secretion provided the 

 breasts be active that is, under the influence of preg- 

 nancy at the time. In animals from which the thyroid 

 is removed at other times inactivity persists, as we 

 would expect. 



According to Ott and Scott 3 , iodothyrin inhibits Effects of 

 mammary secretion. On the other hand Hertoghe 4 



1 Schafer, E. A., and K. Mackenzie, Proc. Ray. Soc. f Ser. B, 

 1911, vol. Ixxxiv, p. 16. 



2 Bell, W. Blair, The Pituitary, 1919. 



3 Ott, I., and J. C. Scott, Therap. Gaz., 1912, vol. xxxvi, p. 761. 



* Hertoghe, E., quoted by H. R. Harrower, Practical Hormone 

 Therapy, 191-4, p. 186. 



