OVARIAN FOLLICLES IN FERRETS AND FERRET-POLECAT HYBRIDS. 305 
of the ovaries preparatory to cutting; and although the ovaries, oviducts, and uterine 
cornua are not so small as in some other mammals, yet they are so small that the 
cutting of them into serial sections does not entail an excessive expenditure of 
labour or time. Further, the ferret is an animal in which ovulation only occurs 
after insemination.*' Therefore it was hoped that it would be possible to establish 
precisely the time at which ovulation and fertilisation occurred. This hope has 
not been entirely fulfilled for reasons which will be explained later. 
Methods. 
Food and Condition. 
I made no stipulations with the dealers as to the feeding of the animals, and 
I understand that whilst they were in their hands they were fed on milk, bread, 
and scraps of rabbits, rats, mice, and birds. Whilst they were in my laboratory 
they were fed on bread and milk only, and they were all healthy and in good 
condition at the time of death, except one which suffered from rupture of the 
uterus during parturition and died twelve hours afterwards. 
All the animals were killed by chloroform narcosis. They were placed in a 
jar full of chloroform vapour ; in it they showed no fear and very little excitement ; 
in a few seconds they were unconscious, and they were dead within ten minutes. 
The method was chosen because one of the points to be determined was whether 
or not there was effusion of blood into the cavity of the ovarian follicles at the 
time of rupture, and it was essential, therefore, to have as little as possible of 
excitement and struggling at the time of death. 
Fixation. 
Immediately after death the abdomen was opened ; each uterine cornu was cut 
through close to the body of the uterus, which is very short in the ferret ; the 
cut end of the cornu was held in the forceps, the broad ligament was divided 
with scissors to a point cranial to the attachment of the ovary, and the uterine 
cornu, with the ovary and the oviduct, were placed in the fixation fluid, care 
being taken to avoid any contact of the ovarian capsule with anything outside 
the body of the animal except the fixing fluid. In some cases the fixing fluid 
was heated to body temperature, and in other cases it was at the temperature of 
the laboratory ; the results obtained by the two methods were not essentially 
different. 
The fixing fluids were : Zenker ; Maximow ; strpng Flemming, with from 2 to 3 
per cent, of acetic acid; Mann’s picro-corrosive sublimate, without and with formol ; 
Perenyi ; picro-nitric acid solution, with 5 per cent, formol ; Lenhossek’s fluid. 
* Marshall made the same statement in 1904 (21) ; but in 1910 (22, p. 136) he seems to have modified his 
opinion, for he writes : “ In the ferret ovulation occurs during oestrus, but postponement of coition may bring 
about the degeneration of the ripe follicles, since they do not always discharge spontaneously.” 
