188 
CHAS. H. O’DONOGHUE. 
. Introduction. 
The following investigation was suggested to me by 
Professor J. P. Hill, whom I have to thank for the material 
upon which it was carried out, together with valuable data 
regarding it, and also for the kindly help he has afforded me 
throughout the course of the work. 
A large amount of work has been done on the growth of 
the mammary glands during pregnancy in the Eutheria, but, 
as far as I have been able to discover, no one has hitherto 
studied the growth of these glands in the marsupials. In 
this group, however, owing to the comparatively short 
duration of intra-uterine gestation, one would expect the 
relation of this growth to the other changes occurring at the 
same time to be less obscure than in the higher mammals. 
The animal chiefly investigated was the Australian native 
cat, Dasyurus viverrinus, a small marsupial which has a 
breeding season once a year. This is a feature of importance, 
as it permits the whole of the genital org'ans, mammary 
glands and associated structures to return to a condition of 
complete rest between the breeding periods, whereas in some 
of the higher animals, for example in the rabbit, a frequent 
subject of investigation, they are practically in a constant 
state of activity. 
Hitherto only two papers have dealt in any way with the 
mammary apparatus of Dasyurus. Firstly, Katz (26), in 
1882, gave a description of the macroscopic appearances in 
the development of the pouch of the young animal, and 
secondly, Bresslau (8), in 1901, examined and figured one 
stage of this animal in the course of a general description of 
the microscopic development of the pouch and teats in the 
marsupials. 
Sandes (42), however, has published a valuable account of 
the development of the corpus luteum in Dasyurus based 
on material from the collection of Professor J. P. Hill. 1 
have had free access to the same collection, and have been 
able in a number of cases to study the animals whose ovaries 
