134 A. A. W. HUBRECHT. 
glandular products contained in the lumen of the uterus, in 
its epithelium, in its subepithelial layers, and in its blood- 
vessels matter is available which can be easily transformed 
into such nutritive material for the embryo the moment a 
means of transport and elaboration of this material is avail- 
able. That the trophoblast does serve as such is also recog- 
nised by all observers. 
Now [I hold it probable that the first and strongest claim 
to which the blastocyst had to answer, when viviparity 
gradually came about, was that of fixation. We will find a 
proof of that by and by when we come to discuss the 
phenomena in Lemures. ‘lhe most natural arrangement for 
the attachment of a growing blastocyst that is passing 
outwards through a cylindrical uterus was the zonary attach- 
ment which would be the simplest possibility by which the 
two surfaces might adhere together. This has been retained 
in the Carnivora and some other mammals (Hlephas, etc.), 
and as such seems to have a primary significance. When 
firm attachment could be combined with phagocytosis it 
would be asafer arrangement than phagocytical absorption of 
elements contained in the uterus lumen without firm attach- 
ment; in this latter case expulsion of the growing blastocyst 
might be a dangerous possibility. And so the firm zonary 
attachment, combined with destruction and digestion of the 
maternal uterine epithelium, might be the next step which 
we also find realised in the Carnivora, to which then and there 
is added further extension of the phagocytosis by the diverse 
processes which have been so carefully analysed and so 
lucidly described by Bonnet (’02). The maternal tissae— 
whether we accept Strahl’s, Bonnet’s, or Schoenfeld’s views 
concerning the maternal epithelium and the trophoblast—is 
universally recognised to undergo catalytic changes, and to 
pass into a symplasma, towards the composition of which 
superficial epithelium, proliferated epithelium of crypts and 
glands, subepithelial connective tissue, leucocytes, and blood 
have all largely contributed. This symplasma, thus prepared, 
is thereby made fit for the phagocytic absorption by the 
