GROWTH-CHANGES IN MAMMARY APPARATUS OE DASYURUS. 227 
satisfactory theory of the causation of milk secretion. That 
of the removal by parturition of an inhibitory stimulus 
originating in the placenta or foetus does not meet all 
cases. 
Addendum. 
Since the manuscript of this paper was sent for publication 
in January several communications dealing with the function 
of the corpus luteum and with the growth of the mammary 
gland have come under my notice, I propose therefore to 
refer briefly to some of these. 
Tandler (58) and Foges (54) have come to the conclusion 
that “ intra-uterine, pre-puberty, and puberty growth of the 
breasts is directly dependent on ovarian function” (vide 
55). 
Frank and Unger (55) have reported that a series of growth 
changes occur in the virgin rabbit resulting in conditions 
“ which were indistinguishable from those seen at the end of 
the first third of pregnancy.” This fits in with the descrip- 
tion I have given above of the changes that take place in the 
mammary apparatus of Dasyurus when ovulation is not 
succeeded by pregnancy. It is a further example of 
mammary growth that cannot be ascribed to the influence 
of either foetus or placenta. 
They further note that these virgin rabbits may have 
breasts more developed than those of the ninth or tenth day 
of pregnancy as described by Claypon and Starling (31). 
This further emphasises the criticism of th$ results obtained 
by these authors made in my paper. Precisely the same 
criticism, namely that in none of the experiments was any 
attention paid to, or allowance made for, this growth of the 
mammary glands in non-pregnant animals, applies also to 
the work of Foa (53) and Biedl and Koenigstein (52). These 
investigators performed a series of experiments somewhat 
like those of Claypon and Starling and arrived at more or 
less similar conclusions. 
Basch (51) in 1909 put forward the view that an inter- 
