of pregnancy. In the primiparous rabbit termination of pregnancy at 

 any time after the fifteenth day results in the appearance of milk in the 

 mammary glands, a result which has also been observed in the human 

 female under corresponding conditions. That this onset of lactation is 

 not due to any stimuli, chemical or nervous, received by the mammary 

 glands from the involuting uterus or ovaries is shown by the fact that it 

 may be brought on by performing total extirpation of ovaries and pregnant 

 uterus. The essential feature therefore seems to be in this case the 

 removal of the growing foetuses. 



These facts demonstrate the intimate connection between the growth 

 and activity of the mammary glands and the growth of the foetus in utero- 

 Many facts point to a close nervous connexion between the mammary 

 glands and the uterus. I need only instance the production of uterine 

 contractions on putting the child to the breast, and the occurrence of 

 hypertrophy of the breast as a result of abnormal uterine conditions. It 

 is, therefore, only natural that the growth of the mammary glands in 

 pregnancy should have been regarded as determined reflexly through the 

 central nervous system, and the nervous nature of the nexus between 

 the generative organs and the mammary glands is still maintained by 

 some writers, such as von Basch, who, however, locate the centres 

 involved in the ganglia of the sympathetic system. There are many facts 

 which militate against our acceptance of such a view. I need mention 

 only some of the more striking of these. Ribbert transplanted in a 

 guinea-pig a mammary gland to the neighbourhood of one ear. The 

 occurrence of pregnancy in this animal was attended by enlargement of 

 the transplanted gland, from which milk could be expressed at the termin- 

 ation of the pregnancy. A similar experiment was made by Pfister on 

 the rabbit. Goltz and Ewald extirpated in the dog the whole of the 

 lumbo-sacral cord. Pregnancy in this animal was attended by enlarge- 

 ment of the mammary glands, and the bitch suckled its pups normally. 

 Von Basch suggests that in this case the nervous connexion could still be 

 through the sympathetic system. Apart from the fact that there is no 

 such connexion possible in the sympathetic system, which since Langley's 

 researches is no longer the happy hunting-ground for speculative reflexes, 

 von Basch's own experiments tell against such a hypothesis. Von Basch 

 extirpated different portions of the abdominal sympathetic in the dog and 

 rabbit and found that at the next pregnancy the glands showed their 

 usual signs of activity. The only difference he observed between such 

 animals and normal ones was a certain increase in the colustrum corpus- 

 cles, an unimportant difference which might have been occasioned by any 

 trivial circumstance. Physiologists are therefore ready to believe that the 

 nexus between generative organs and mammary glands is a chemical one, 

 though opinions differ widely as to the seat of formation or origin of the 

 chemical stimulus. 



Pregnancy commences with changes in the ovary i.e., ovulation. 

 The occurrence of fertilisation involves growth of the ovaries with their 

 corpora lutea, growth of a fcetus which soon enters in the mammal into 

 close relationship with the maternal circulation, and growth of the uterine 



