EARLY OXTOGEXETIO RHEXUMEXA IX MAMMALS. 263 
I appeal to Professor Hiibreclit to let us retain the word 
“ placenta ” for all types of foetal connection between mother 
and offspring for tbe purpose of nutrition^ at any rate within 
the class Mammalia. 
The size and shape of the uterus^ the character of the sub- 
mucosa, the nature of the uterine glands, are, of course, all 
features which have exercised profound effects upon the 
character of the attachment between mother and offspring, 
but I cannot see that they could be compared in morpho- 
logical importance to the organ Avhich alone makes them of 
any use at all. To say that the laterally expanded tropho- 
blast and the distended allantois of the Ungulates^ “ placenta'’ 
is not an organ equivalent in all respects morphologically and 
physiologically with the more compact and confined mass of 
trophoblast and allantois of a hedgehog or rat, because the 
former obtains its nourishment largely from the glandular 
secretions, seems to me to be scarcely tenable. 
No doubt the time is not yet i-ipe for using the placenta 
even as a broad means of classification, but liiibrecht’s own 
work, especially that on Tarsius, has indicated that the 
placenta will be found eventually to have most important 
diagnostic value. 
And I venture to predict that when that time does come the 
characters on which the main classification will rest will be 
characters of the allantois and trophoblast rather than 
maternal features, important though the latter may prove to 
be for the smaller subdivisions. As Hubi’echt allows, the 
young blastocyst at any rate is parasitic in its relation to the 
mother ; and is it not customary to classify parasites more by 
their own morphological and physiological features than by 
the effects which they have upon their hosts? 
Although I did not suggest the terms “ cumulate ” and 
“ plicate” as terms for a classification of mammalia on these 
lines, still for the present these terms seem to me to represent 
the essential character of two extreme forms of mammalian 
placenta. The characters of the two types may be tabulated 
thus : 
