140 
J. 1*. HILL AXH ('HAS. H. o’dONOCHIUE. 
any record of a female once served^ again copulating during 
that season. Asa matter o£ fact, our experience has been 
that a female, once copulation has been effected, will invari- 
ably fight any male subsequently introduced into the breeding 
cage. Moreover, study of the ovaries in section has shown 
that ovulation, even in females wdiich have not become preg- 
nant, is not followed by the growth of a second batch of 
follicles. The cestral cycle in Dasyurus is thus a simple one^ 
and as only one such cycle occurs in the breeding season, the 
animal is monoestrous. Our records show that Trichosurus,. 
Phascolarctos (cf. Semon (25) and Caldwell) (5)), Phasco- 
lomys and probably the Macropods (cf. Caldwell, loc. cit.) 
breed only once a year, but as to whether they are monces- 
trous, we have no definite evidence of our own to offer. 
Pro-cestrus commences early in June and appears to 
occupy a period of time varying from four or five to perhaps 
as long as ten or twelve days. It is marked by an cedematous- 
swelling of the lips of the cloacal aperture, and at the same 
time the pouch enlarges somewhat and becomes tumid, whilst 
its interior sometimes becomes slightly moist. The tumidity 
is mainly the result of the enlargement of the sebaceous glands- 
of the pouch area. The sweat-glands also hypertrophy and 
become more coiled. The sebaceous and the sweat-glands soon 
become active; in the former the cells start to undergo auto- 
lytic disintegration, and in the latter they become granular. 
The gland lumina increase and become filled by secretion, 
which, on being discharged, causes the interior of the pouch 
to become moist and somewhat sticky (vide 20). 
Practical no change takes place in the mammary glands- 
during this period. 
In the ovary, the Graafian follicles gradually enlarge, and 
as they approach maturity, they form prominences on its 
surface. 
Uterine Changes. 
AVe have examined sections of the uteri of three females in 
the pro-cestral condition. 
