SPOLIA NEMORIS. 107 
his views, is there from the very first and forms the greater 
part of the wall of the monodermic blastocyst. 
In support of these views the author discusses the existing 
figures and descriptions of early mammalian blastocysts with 
considerable ingenuity. A couple of very difficult cases, which 
I see no possibility of including in Robinson’s speculative 
attempt, are, however, by him passed over in silence. As 
such I would, for instance, point out Selenka’s fig. 2, pl. 18, 
of the opossum (‘ Studien z. Entwickelungsgesch. der Thiere,’ 
Heft 4), as compared both to earlier and later stages. 
On p.46 of Merkeland Bonnet’s ‘Ergebnisse der Anatomie und 
Entwickelungsgeschichte’ (vol. 11, 1892), G. Born, in referring 
to Robinson’s paper, recognises that if the views therein con- 
tained were confirmed, this would mean a total revolution of 
our present interpretation of the earlier stages of mammalian 
ontogeny. Born adds, “an der nothwendigen Nachprifung 
der Resultate wird es nicht fehlen.” 
Such a “ Nachprifung” can be fully instituted with the aid 
of the material now in my possession. Already have I examined 
continuous section series through more than sixty segmentation 
stages and mono- and didermic blastocysts of Tupaja that 
had not yet adhered to the uterine wall, and through fourteen 
preparations of the same early stages of Tarsius. 
I will elsewhere fully report about these preparations, but 
may be allowed now already to assert that they go dead against 
Dr. Robinson’s speculations, and that I have no doubt that 
certain peculiarities observed in Tupaja will convince even 
Dr. Robinson of the fact that the outer layer of the mamma- 
lian monodermic blastocyst (i.e. the trophoblast) is not in 
direct continuity with the hypoblast cells inside of it. 
On the other hand, we must recognize in Dr. Robinson’s 
speculations, as also in the preceding attempt of Minot (I. c.) 
and Keibel (‘ Anat. Anzeiger,’ vol. ii, p. 770),! laudable efforts 
1 Tcannot admit with Keibel the possibility of a ‘ Wachsthumsenergie 
derjenigen Zellen des Hies welche friiher den Dotter umwuchsen,” which 
would be unchecked for millions of generations after the disappearance of the 
yolk, and which is by him meant to explain certain formative processes in the 
blastocyst. 
