98 M. Coste on the Formation of Cells. 



it. This is the manner in which the phsenomenon of the multi- 

 phcation of the vitelUne spheres ensues ; but this phsenomenon, 

 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 

 phsenomenon^ 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 j 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. It is 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 



