98 INFLUENCE OF HORMONES 



in twenty-four hours, and the amount of hormone it 

 contained may have been absorbed in a very short 

 time. The amount of growth obtained experi- 

 mentally in five weeks was less than that occurring 

 in pregnancy in nine days. Extracts of uterus, 

 placenta, or ovary produced no growth, although the 

 ovaries used were taken from rabbits in the middle 

 of pregnancy. In one experiment ovaries from a 

 pregnant rabbit were implanted into the peritoneum 

 of a non-pregnant rabbit, but on post-mortem 

 examination of the latter eleven days later the im- 

 planted ovaries were found to be necrosed and no 

 proliferation of milk gland had taken place. 



The conclusions of Starling and Lane-Claypon were 

 confirmed by Foa,^ and by Biedl and Konigstein.^ 

 Foa states that extracts of foetuses of cows also pro- 

 duced swelling of the mammae in a virgin rabbit. 



O'Donoghue, how^ever, concludes from a study of 

 the Marsupial Dasyurus that the stimulus which acts 

 upon the milk glands proceeds from the corpora 

 lutea in the ovary. In this animal changes in the 

 pouch occur in pregnancy, which are doubtless also 

 due to hormone stimulation, but which we will not 

 consider here. The most important evidence in 

 O'Donoghue' s paper ^ is that development of the milk 

 glands takes place after ovulation not succeeded by 

 pregnancy ; that is to say, when corpora lutea are 

 formed but no fertilised ova or foetus are present in the 

 uterus. In one case, eighteen days after heat, the 

 milk gland was in a condition resembling that found 

 in the stages twenty-four and thirty-six hours after 



^ Archivio d. Fisiologia, v., 1909. 



2 Zeitschrift f. exp. Path, und Therap., 1910. 



3 Quart. Journ. Mic. Sci., Ivii,, 1911-12, 



