6io THE PHYSIOLOGY OF REPRODUCTION 



Notwithstanding the fact that the transplanted gland- had lost its 

 normal nervous connections, it underwent enlargement during a 

 subsequent pregnancy, and afterwards secreted milk. Pfister ^ states 

 that he performed a similar experiment on a rabbit, and obtained 

 a similar result. 



The inference is, therefore, that the relation between the growth 

 of the mammary glands and the development of the foetus in the 

 uterus is chemical in nature. 



Lombroso and Bolaffio^ have described an experiment in which 

 two female rats were grafted together so that their respective 

 circulatory systems were presumably united. Subsequently to their 

 union they each became pregnant, but at different times. They 

 afterwards produced young, one prematurely, and the other at full 

 term. The mammary glands of each underwent the characteristic 

 changes, but they occurred independently and not synchronously. 

 The authors cite this result as evidence against the foetal hormone 

 theory. Moreover, as a result of this and another similar experiment, 

 they conclude that parturition is not induced by a chemical excitant 

 circulating in the blood (see p. 574). 



On the other hand, in the case of the Bohemian pygopagous 

 twins, Rosa-Josepha, the mammary glands of both are described as 

 having been similarly and simultaneously afi'ected by the pregnancy 

 of Rosa, who bore a healthy boy on April lY, 1910. Milk was 

 afterwards secreted by the breasts of Josepha as well as of Rosa, 

 although Josepha had never conceived.^ 



As Miss Lane - Claypon and Starling have pointed out, the 

 phenomenon of fertilisation succeeded by fcetal growth involves 

 the occurrence of changes in the ovaries and in the uterus (both in the 

 muscle and in the mucous membrane), as well as the formation of an 

 organ of complicated structure — the placenta — :the function of which 

 is to nourish' the developing young. The question arose, therefore, 

 as to whether the foetus or either of the above-mentioned organs was 

 not the direct source of formation of a hormone or chemical excitant 

 which, after circulating in the blood-stream, acted as a stimulus to 

 mammary growth. 



1 Pfister, "Ueber die refiektorischen Beziehungen zwischen Mammae und 

 Genitalia muliebria," Beitrage zur Geh. wnd Oyndk., vol. v., 1901. 



^ Lombroso and Bolaffio, "La Parabiosi e la Questione dei Fattori che 

 determinana la Fuz Funzione mammaria e I'lnsorgenza del travaglio di parto," 

 Aiti delta Soc. Ital. di Obstet. e. Gin., vol. xv., 1909. 



3 British Med. Jow., Part XL, 28tli May 1910. The twins were described 

 as being united posteriorly by a common sacrum, but the iliac bones were 

 separate. There was a common anus, perineum, clitoris, and meatus urinarius, 

 but the labia majora were double. The urethra was single for an inch above 

 the meatus,- but then it bifurcated. The ureters were normal. The desire to 

 micturate was said to be distinct, but not the desire to defsecate. The twins 

 died at the same time in April 1922. 



