108 A. A. W. HUBRECHY. 
where its proliferation is equally strong all over the surface. 
On the contrary, in the mouse, in Arvicola, Cavia, and others 
there is a very marked centre of proliferation, which will after- 
wards become the placentary attachment, and which already, 
in the very early stages, consists of an accumulation of tro- 
phoblast cells to which Selenka has given the name of Trager 
(supporter) (Figs. 24—28). 
The phenomena recorded in this chapter are not considered 
in the same light by all authors. Notably Strahl’s interpreta- 
tions contained in his extensive researches on this subject 
(89 to 92) and in his chapter on mammalian placentation to 
Hertwig’s Handbuch, differ considerably from my own. 
He is inclined to ascribe a much more considerable signifi- 
cance to the part which maternal tissue plays in the full- 
grown placenta. Many of the trophoblastic proliferations 
described in this chapter are by him considered to be of 
maternal origin. The latest author, however, who has 
thoroughly investigated the subject and who has published a 
very lucid exposition of his results, Schoenfeld (03), adopts 
my views (l.c., p. 814), and differs both from Strahl and from 
Bonnet (797-01). The latter, though also studying the dog, as 
did Schoenfeld, has probably declined to accept the possibility 
(“le fait pouvant paraitre bizarre” Schoenfeld) of the exist- 
ence of a mixed plasmodium in which both foetal and maternal 
elements are represented. Such a plasmodium was detected 
by myself in Tarsius (99, Figs. 62—64) and Tupaja (99, 
Figs. 51—54), by Schoenfeld in the dog (l.c., Pl. 24, fig. 6), 
and enabled the latter author to establish the real nature of 
the placenta of the Carnivora, towards the interpretation of 
which the views of Duval (94, 795) and Strahl (’90a, ’94) 
presented conflicting interpretations. 
I may add that Schoenfeld’s results according with and 
confirming those which I had obtained in Insectivores and 
Primates (and equally applicable to the rabbit, which was 
also personally investigated by Schoenfeld) seem to me to 
open up a line of research by which we will be able better to 
understand the placentation of those Ungulates and Lemurs, 
