22 Microscopical Besearches on the Conformity of 



quences 'which must go to form a theory of the organisation and growth 

 of organised beings. Wc shall here present its principal features. 



The most recent discoveries in the physiology of plants have demon- 

 strated that the formation of the cellular tissue, the fibres, vessels, and 

 spiral vessels, is reducible to that of cells. The origin of cells has been 

 illustrated by an important discovery of M. Schleiden's) Midler's Archiv, 

 1888, p. 137). His starting point is what R. ^rown calls the nucleus of 

 the cell, which M. Schleiden names, for this reason, cytohlast. Its colour 

 is most commonly yellow, its internal structure granular. Schleiden has 

 even discovered in the interior of the cytoblast a corpuscle, the corpuscle 

 of the nucleus, which appears sometimes in the form of a spot, some- 

 times under that of a hollow globule. These cytoblasts are formed freely 

 in the interior of the cells among a mass of minute mucous globules ; aS 

 soon as they have attained their full growth, a very small transparent 

 vesicle rises on their surface, which is raised above the cytoblast like a 

 watch-glass above the dial-plate. 



In proportion as this cell enlarges, the cytoblast appears like a body 

 enclosed in one of the walls of the young cell ; its wall, on the inner side, 

 is extremely thin, and, as it were, gelatinous ; it can seldom be observed, 

 and is soon absorbed with the cytoblast. The young cells are free in the 

 mother cell, and assume a polyhedral form by pressing closely against 

 each other. Now this is in what M. Schwann's discoveries essentially 

 consist, regarding the cells of animals, and the primitive conformity of 

 structure between animals and plants. 



In the Chorda dorsalis, of which I have long since demonstrated (says 

 ^M. J. Miiller) the cellular structure, M. Schwann has found the nuclei 

 of the cells ; each cell of the Chorda dorsalis^ of the Pelohates fuscus, has 

 its lenticular cytoblast, applied against the interior wall of the cell ; and 

 we perceive in this small lenticular body one well defined spot, rarely 

 two or three. In the interior of the cells of the Chorda dorsalis, young 

 free cells are formed, as among plants. 



The primitive structure of the cartilages is, according to M. Schwann, 

 entirely cellular. At the extremity of the cartilages of the branchiostegial 

 rays of fishes, we perceive small polyhedral cells, closely pressed upon 

 each other, and whose walls are extremely thin. These cells have a round 

 granular nucleus. Towards the centre of the ray, we notice the parti- 

 tions of the cells thicken more and more. Looking still further towards 

 the base of the ray, we cease to perceive the separation of the cells, and 

 there remains only the appearance of a homogeneous substance, in which 

 nothing is seen but small insulated cavities j around each cell, however, 

 there is a ring indicating a trace of the true cellular wall ; whence it 

 follows that all the intermediate substance of the cellular cavities cannot 

 be formed by the walls of the cells, but that the intercellular substance 

 here essentially contributes to the formation of cartilage. This intercel- 

 lular substance may be perceived even when the walls of the cells are 

 still touching each other; they appear under the form of a triangle, situate 

 between three contiguous cells. The formation of the cartilage here de- 



