372 A. A. W. HUBRECHT. 
them in the form of separate paragraphs at the conclusion of 
this memoir. 
1. The ventral stalk (Bauchstiel, His) of the human embryo, 
and the questions concerning the allantois, the amnion, and the 
placentation of man. 
W. His, who was the first to investigate more fully the solid 
stalk of tissue, by which the early human embryo is attached 
to the wall of the blastocyst, gave to it the now more generally 
accepted name of ‘ Bauchstiel.” Up to that time it was 
termed the “allantoic stalk,” it being supposed that it arose 
from the allantois which, growing out from the embryo, had 
brought about the well-known secondary connection between 
embryo and serous envelope. His writes (‘Anatomie Mensch- 
licher Embryonen,’ i, p. 170): ‘ Repeatedly attempts have 
been made to discover a vesicular free allantois, and to fix the 
period at which this leaves the body and advances towards the 
chorion. Analogy with the development of other animals, led to 
the supposition that at a certain moment the human embryo, 
enclosed in the amnion, is freely suspended in the chorionic 
cavity, and that only at the time of the appearance of the 
allantois, of its growth and fusion with the chorion, the bridge 
was completed by which henceforth the nutritive matter could 
be carried towards the embryo.” 
His goes on to compare this with what the facts concerning 
the earliest human blastocysts, with which we are acquainted, 
teach us, and he finds considerable contradictions and discre- 
pancies. Starting from these facts he adopts the view that the 
embryo is never separated from the chorion, and that the 
‘ventral stalk ” is the never-interrupted point of connection 
between the embryonic and the chorionic part of the original 
blastocyst. 
In order to explain the secondary closure of the chorion 
above the embryo, he connects the formation of the amnion 
with the formation of a region, which he calls “ the secondary 
portion of the chorion.” The primary chorion,” His writes 
(l. ¢., p. 172), “is the lower part and the periphery of the 
