GROWTH-CHANGES IN MAMMARY APPARATUS OF DASYURUS. 213 
after parturition. Ribbert (40), transplanted one of tbe 
mammary glands in the guinea-pig to the region behind the 
ear, and this transference did not stop the onset of normal 
hypertrophy and milk secretion. Golz and Ewald (18), 
removed the lower part of the spinal cord of a pregnant 
bitch, and Routh (41) records the case of a pregnant woman 
whose spine was crushed at the level of the sixth dorsal 
vertebra, and in both these instances parturition followed by 
suckling occurred in the normal manner. Finally there is 
the case of the pygopogous Bohemian twins (46), in which the 
cardae equinae of the two spinal cords are probably separate. 
One of these, Rosa, conceived and gave birth to a boy on 
April 17th, 1910, and the breasts of the other, Josepha, 
enlarged simultaneously with those of her sister during the 
pregnancy of the latter. After the birth of the child, milk 
was secreted by the glands in Josepha although she had never 
been pregnant. 
From these facts it would appear that the growth of the 
mammary gland is due to the presence of some specific 
inciting substance carried by the blood, and not to the 
nervous connection between ovary and uterus. In Dasyurus, 
at any rate, this substance may also act as a stimulus to the 
adjacent sebaceous and sweat-glands. 
The Origin of the Stimulus. 
Lane-Claypon and Starling (31), as the result of an 
experimental inquiry into the factors causing the growth of 
the mammary gland of the rabbit during pregnancy, came to 
the conclusion that it was due to “ the action of a specific 
stimulus produced in the fertilised ovum.” Heape (21), 
however, does not agree with this interpretation that the 
substance comes from the embryo, and brings forward as 
evidence against it the facts that (1) “the beginning of the 
development of the gland dates from some point prior to, or 
during, pro-oestrus, and occurs normally apart from preg- 
nancy”; and (2) “that full functional development of the 
gland may be experienced by virgins, and therefore without 
