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CHAS. H. o’dOXOGHUE. 
(loc. cit.) to correspond with ovulation, which occurs by the 
bursting of the Graafian follicles, and is followed by the 
formation of the corpora lutea. It would seem, then, that it 
is to these structures, formed after each ovulation, that we 
must look for the seat of the production of the stimulus 
causing the growth of the mammary glands. 
The view that the corpus luteum is a ductless gland was first 
suggested by Prenant ( 37 ), and this has been maintained by 
most of the workers since his time. Indeed, Regaud and 
Policard ( 39 ), in the hedgehog, have demonstrated by means 
of special methods of staining the presence of specific secre- 
tory drops in its cells. 
The Functions of the Corpus Luteum. 
Gustav Born suggested that the function of this ductless 
gland was to secure the attachment of the embryo to the wall 
of the uterus, and accordingly Fraenkel and Cohn ( 15 ) in 
1901 and Fraenkel ( 14 ) in 1903 performed a number of 
experiments upon rabbits to elucidate this point. The con- 
clusions they arrived at were, that the corpus luteum is a 
ductless gland whose function is to regulate the nutrition of 
the uterus, and to prepare its mucous membrane for the 
maintenance of the fertilised ovum. Marshall and Jolly 
(loc. cit.), after a series of experiments on bitches and rats, 
came to much the same conclusion as Fraenkel and Cohn, 
namely, that “ after ovulation, which takes place during 
oestrus, the corpus luteum is formed, and this organ provides 
a further secretion whose function is essential for the changes 
taking place during the attachment and development of the 
embryo in the first stages of pregnancy.” Now Fraenkel 
(loc. cit.) had found that if the corporea lutea alone were 
destroyed by cautery at any time during the first six days 
of pregnancy, while the rest of the ovary was left intact, 
then pregnancy came to an end. Similar experiments on 
rabbits have recently been made by Kleinhaus and Schenk 
(27), who found that if the corpora lutea were destroyed 
during the first nine days of pregnancy abortion invariably 
