GROWTH-CHANGES IN MAMMARY APPARATUS OF DASYURUS. 203 
expansion of the alveoli, have been spread out and brought 
close to their walls. 
It has already been stated that towards the end of pregnancy 
the glands secrete a substance which is expressible from the 
teat of the living animal as a clear lymph-like fluid. The 
coagulum of the secretion is present in the acini and ducts of 
the gland, and is very similar in appearance to colostrum. 
Changes after Parturition. 
The Cutaneous Glands of the Pouch Area. 
Both the sebaceous and the sweat-glands have reached 
their maximum size early in pregnancy and after parturition 
they appear to remain constant and in a state of moderate 
activity, so that the pouch is kept soft and moist for the 
contained young. 
The Mammary Glands. 
Little change, if any, is noticeable in the mammary gland 
itself immediately after parturition ; the gland mass has 
perhaps enlarged a little in bulk owing to the slight increase 
in the size of the alveoli. 1 No further increase in the actual 
number of glandular cells appears to take place after the birth 
of the young, for very careful searching of the sections failed 
to reveal any sign of mitotic or amitotic cell division. There 
is a gradual increase in the size of the alveoli up to the 
time when the young have been in the pouch four months 
(No. 25), and at this stage, when fully distended by 
milk, they are of enormous dimensions compared with the 
size of the newly-formed alveoli. 
As in the case of man the secretion of milk does not occur 
immediately after parturition. Examination of the sections 
shows that the birth of the young has no immediate effect on 
the condition of the mammary glands, which is the same 
1 The condition of the mammary glands in Perameles nasuta 
just after the birth of the young (No. 31) is very similar to that of the 
glands of Dasyurus at the same time (No. 18). 
VOL. 57, PART 2. NEW SERIES. 
16 
