Royal Microscopical Society. 
5 
as I could nowhere discover evidences of a process of multiplication 
by a direct division of the nuclei, almost inclined me to think more 
seriously of a primary formation of nuclei from the plasma itself. 
It was not until I met in the epithelium, covering the villi of the 
chorion of a human embryo of about 16 mm. in length, with nuclei, 
provided with vesicles or their corresponding depressions, that my 
attention was called to the process of multiplication by budding or 
gemmation. But further proofs in corroboration of this idea were 
still wanting, until chance threw the small human ovum under con- 
sideration into my hands, in the membranes of which I observed 
the whole process in full operation. 
Besides these mother-nuclei, a considerable number of others, of 
a more or less oval form and bearing no vesicles, were imbedded 
in the membrane ; they were distinguished by a double contour 
and a fine granular aspect, containing a number of fine granules. 
A small number of nucleated cells of a granulous appearance were 
further observed here. The concave depressions, which many of 
these bodies showed upon the surface, inclined me to look upon 
them as mother-cells. 
The villi, arising from the chorion of the ovum, were tuberous 
bodies, connected to each other in a manner similar to that of the 
branches of a tree, by shorter or longer stems. (Fig. 2.) To the 
larger bodies, smaller pear-shaped ones were attached by means of 
fine pedicles. The entire tree-like body thus formed seemed to bo 
connected by a fine stem to the membranous chorion. But by a 
closer examination, and after the removal of the epithelium, I found 
that this stem arose in reality from the membrane, by a number of 
fine branches or roots. (Fig. 1.) The tissue of the villi resembled 
that of the chorion itself ; it consisted of very fine granular fibrillae, 
with a number of more or less oval nuclei imbedded in it. The 
epithelium covering the membranous portion of the chorion, and 
extending over the villi, consisted in this small ovum of a granular 
matrix with oval nuclei, a considerable number of which were pro- 
vided with the above-described vesicles and concave depressions. 
This fact proves that it is a production of the ovum itself. 
The inner membrane of this ovum consisted of a loose, spider- 
web- like connective tissue of fine, wavy fibrillae, containing a 
number of free nuclei and nucleated cells. Some of these latter 
were open, and apparently in the act of setting free their nuclei, 
showing that here the process of multiplication took place by the 
endogenous mode. Besides these, however, a number of small 
nuclei-bearing vesicles were also observed. No trace of epithelium 
could be discovered on the inner surface of this membrane. 
Let us now direct our attention to the formation of the primary 
blood-vessels, such as I observed it to occur, not only in the cho- 
rion of the small ovum above described, but also in that of some- 
