EEPKODUCTIVE CYCLE IN DASYUKUS VIVERRINUS. 169 
rative changes in the mucosa, followed as they are by regene- 
rative growth, is of the nature of an adaptation, of obvious 
advantage, as is generally recognised, from the point of view 
of early placental formation (embedding, trophoblastic 
attachment, etc.). 
Whilst, then, we believe that the uterine changes charac- 
teristic of the pseudo-pregnant period in the marsupial have 
been shifted forwards to pro-oestrus in the Eutheria, it remains 
to be pointed out that amongst the Eutheria, alterations in the 
ovary and mammary gland corresponding to those seen in the 
pseudo-pregnant marsupial have indeed been recognised, but 
do not appear to have been brought into correlation with the 
oestral cycle. 
Various authors (e. g. Ancel and Bouin (1) ) have described 
the formation of corpora lutea spuria, so-called, which 
in animals ovulating* spontaneously, last for a shorter time 
than in the pregnant female. 
Further, as regards the mammary glands, it has been stated 
(Frank and Unger (6) and others) that a growth of these 
occurs during the oestral cycle, and according to Ancel and 
Bouin ( 2 ), only after the formation of corpora lutea. One of 
us (O’D.) has evidence confirmatory of this latter statement so 
far as concerns the rabbit. 
These changes in the ovary and mammary glands have 
thus retained their original position in the cycle, i. e. they 
occur after oestrus and ovulation as in the marsupial. 
The Monoestrous and Polyoestrous Conditions. 
According to Heape ( 11 ), monoestrous mammals are those 
which experience a single oestrus during’ each sexual season, 
i. e. in which the anoestrous cycle alone occurs, whilst poly- 
oestrous mammals are those whose sexual season is occupied 
by a series of dioestrous cycles, or in other words, those who 
experience a series of recurrent oestri (p. 9). Heape 
questions if in the present state of our knowledge it is 
possible to determine which is the original of these two con- 
