222 
CHAS. H. o’dONOGHUE. 
half of pregnancy cannot be due to the corpora lutea, as 
these bodies are diminishing or have disappeared. It is very 
probable, however, that the growth after the first fourteen 
days is due largely to an increase in the size of the individual 
cells and a distension of the alveoli and ducts., for in the 
specimen I have examined, No. 35, the formation of new 
glandular cells has ceased. Now Lane-Claypon aud 
Starling have shown that subcutaneous injections of foetus 
and placenta extracts continued for some time produce a 
marked hypertrophy of the mammary glands. So that there 
are grounds for thinking that in this animal, at any rate, the 
presence of a foetus may have something to do with the con- 
tinued enlargement of the glands. But it is perhaps a 
significant fact that in these experiments there is no unequi- 
vocal case in which a secretion of milk resulted, although the 
injections in one case were continued forfive weeks. Further, 
the whole experiments were somewhat vitiated because there 
was no allowance made for the growth of the gland occurring 
at each oestral period. 1 
In considering the question of the seat of origin of the 
internal secretion inciting growth in the mammary glands, we 
have to take into account the following facts : 
(1) There is a marked correlation between the formation 
and growth of the corpora lutea and the growth of the 
mammary glands both in the pregnant and non-pregnant 
Dasyurus viverrinus. 
(2) The experiments of Lane-Claypon and Starling, given 
above, show that the removal of the ovary while it still has 
well-developed corpora lutea leads to a regression of the 
mammary glands without functional activity. 
(3) The experiments of Fraenkel and Cohn and of 
Kleinhaus and Shenk (both referred to previously) have 
shown the extreme importance of the secretion of the corpora 
lutea, and not the whole ovary, to the uterine changes in the 
first stages of pregnancy. 
(4) Ancel and Bouin (loc. cit.) showed that a growth of 
1 See Addendum. 
