EARLY ONTOGENETIC PHENOMENA IN MAMMALS. 269 
a strictly cumulate type by way of such couditions as Hylo- 
bates, Semnopithecus, Cercocebus, by the gradual supersession 
of the glandular activity of the maternal uterus over the 
phagocytic activity of the foetal ti’ophoblast, and the filling 
of the blood-spaces, into which the foetal villi originally hung, 
with uterine secretions instead of extravasated maternal 
blood. 
The character of the foetal villi and maternal crypts ai-e 
somewhat different in Nycticebus from those of plicate forms. 
In the plicate forms each villus fits into its own special crypt 
very exactly ; the correspondence is, indeed, extremely inti- 
mate in some cases, e. g. the pig, where the processes of the 
trophoblast cells even penetrate between the cells of the 
uterine epithelium. 
In my specimen of Nycticebus the foetal villi appear to 
hang in grape-like bunches into the mouths of much wider 
depressions, but this character may be artificially exaggerated 
in my specimen, as neither Hubrecht for Nycticebus nor 
Strahl for Galago indicate this character to the same extent. 
Nevertheless, the difference between the true plicate form 
and Nycticebus is very well marked. In such plicate forms 
as Equus, Bos, Tragulus, Orca, Halicore, the foetal villi are 
filose, and fit into distinct crypts in the uterine mucosa, while 
in Nycticebus the foetal villi are more lobose and racemose, 
and can be described better as partially separated from one 
another by lamellate folds of the maternal mucosa, being 
elsewhere separated only by uterine gland secretion. The 
peculiar chorionic recesses described by Hubrecht (’94) are 
recesses where foetal villi project quite freely into a space 
filled presumably with uterine milk, as the recesses are open 
to the inter-foetal uterine space and certainly contain no 
projection of the uterine epithelium itself. Hubrecht says 
(p. 145) : “ Nycticebus has foetal investments which, in the 
latter half of the period of pregnancy, can, together with the 
enclosed foetus, be easily washed out of the maternal crypts, 
the trophoblastic villi not being in any way confluent with 
maternal tissue.” 
VOL. 54, PAKT 2. NEW SERIES. 
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