98 M. Coste on the Formation of Cells. 
it. This is ‘thie manner in which the phenomenon of the multi- 
plication of the vitelline spheres ensues ; but this phenomenon, 
which we have considered as the result of a double influence si- 
multaneously exerted upon each of the segments of the vitellus 
by the division of the fatty globe which occupies its centre,—this 
phenomenon, I say, seems to refer to a still deeper cause, and so 
to speak, to be nothing more than the external and consecutive 
repetition of a more intimate and previously completed process. 
In fact, each central fatty globule contains in its interior a much 
smaller generating globule, and which appears, in regard to the 
fatty globule, to play the same part as the fatty globe fulfils with 
regard to the vitelline spheres by which it is enveloped. So that 
if we review the whole of the facts which the vitellus presents 
during the transformations which we have described, we find that 
the elements to which these metamorphoses give rise are derived 
from one another in a continued series, and are all the result of | 
a triple envelopment. 
This envelopment commences by the appearance of a primor- 
dial globule within the vitelline spheres ; the globule then becomes 
a centre, around which the fatty globule is condensed ; the latter 
subsequently resolves itself into two distinct fragments ; and these 
fragments, enveloping themselves with the vitelline matter, pro- 
duce the granular spheres, the mode of multiplication of which I 
have previously described. 
The formation of the organic spheres by successive envelop- 
ment around a centre, and their multiplication by subdivision, 
are such general facts as to require the whole attention of phy- 
siologists. They are observed in the vitellus of Mammalia, 
Batrachia, the osseous Fishes, Mollusca, insects and worms, 
The so frequent production of these particular forms of matter 
proves, in opposition to the opinion of Schleiden and Schwann, 
that organized bodies are not exclusively composed of cells; but 
that other elements may also enter into the composition of ‘their 
tissues, and that the organic spheres ought to be reckoned among 
these elements. They do not in fact appear only as a transitory 
modification of the vitelline matter undergoing the primary in- 
fluences of fecundation, for they are also found in tissues which 
are undergoing development, and even in those which form a part 
of the adult organism. Itis these which, by their juxtaposition in 
the Mammalia, give origin to the earliest and most important for- 
mation of the tissues of the germ, because the blastodermic mem- 
brane is formed at their expense; that is to say, that which will sub- 
sequently become the basis of the entire organism. It is true that 
by gradual conversion into cells they soon raise the blastodermic 
membrane to a higher degree of organization ; but they reproduce 
it at a period when they are still simple granular spheres, and 
