GROWTH-CHANGES IN MAMMARY APPARATUS OF DASYURUS. 217 
followed. So that there appears to be no doubt that the 
corpus luteura is a ductless gland whose secretion is necessary 
for the attachment of the foetus in its early stages. 
Sandes (loc. cit.) investigated the formation of this body 
in Dasy urus viverrinus, and he thinks that it is probably a 
glandular organ whose secretion influences the genital organs 
and the organism generally, and that it prevents ovulation 
(a function previously attributed to the secretion of this 
structure by Beard [4], but only temporarily if no pregnancy 
occurs. He showed that the formation of the corpus luteum 
was rapid, and that it persisted during the greater part of the 
time that the animal was lactating, and it only disappeared 
when the young animals became independent. This work, as 
was pointed out in the introduction, furnishes the material 
for an interesting correlation between the growth of the 
corpus luteum and of the mammary gland. For the purpose 
of ready comparison I have arranged in five vertical columns, 
firstly, the various stages in the growth of the corpus luteum 
and mammary gland, and secondly, the condition of the 
embryo, of the corpus luteum, and of the mammary gland 
corresponding with them. The stages of the norpus luteum 
are taken from Sandes* list which should be referred to for 
the full details, the stages of the mammary gland from my 
own list of material given above, and the stages of the 
development of the embryo from Professor J. P. HilFs note- 
books. It should be noted, however, that Sandes divides the 
growth of the corpus luteum into three stages : (1) The 
early corpus luteum, i.e. the period immediately after the 
rupture of the Graafian follicle when it is being formed ; (2) 
later corpus luteum, i.e. after the formation is complete, 
but while it is still actually increasing in size ; and (3) a stage 
in which it remains practically constant. 
The same facts may be illustrated in a more striking 
manner by means of a comparison between the curves of 
growth in the two cases. 
From the above it will be seen that as soon as the corpus 
luteum has begun to form the growth of the mammary gland 
