GROWTH-CHANGES IN MAMMARY APPARATUS OF DASYURUS. 189 
have been described by Sandes. I have also been able to 
consult Professor J. P. Hill’s note-books, and am thus in a 
position to correlate accurately the stages of development of 
the embryo, corpus luteum, and mammary apparatus in a 
way that has not been done previously in any mammal. 
Matekial. 
The material consisted of a number of complete pouches 
of Dasyurus viv^rrinus, together with the underlying 
mammary glands, which had been preserved whole in various 
fixing fluids, that giving the best fixation being picro- 
corrosive-acetic acid. The pouches were taken from animals 
in all stages, both before and after parturition, and in each 
case there was available not only a more or less complete 
record of the animal for some time previous to killing, but 
also an exact account of the stage of the embryo, whether in 
the uterus or in the pouch, so that it was easily possible to 
ascertain with what stage of embryonal development the 
growth of the mammary gland corresponded. 
In addition to the Dasyurus material, I have examined 
three stages in the activity of the gland in the domestic cat, 
one stage in Perameles nasuta, one in the rabbit, and one in 
the guinea-pig 1 and these have been compared with the 
corresponding stages in Dasyurus. 
The glands were studied by means of serial sections cut 
through them, aud the teat, generally at 8 or 10 p thick, while 
for finer histological details sections about half the thickness 
were employed. The sections were stained by means of 
Ehrlich’s haematoxylin and eosin, which stain was found, after 
experimenting, to produce the best general results. Great 
care was taken that the changes from absolute alcohol to 
benzole, and from benzole to paraffin wax, should not be too 
sudden, so that the glandular tissue should not be injured in 
any way. 
1 For the last two I have to thank Miss E. M. Simmons, of the London 
School of Medicine for Women. 
