Development of Animal Tissues from Cells. 379 



3. " On the minute structure of the Skeletons, or hard parts of 

 Invertebrata." By W. B. Carpenter, M.D. Communicated by the 

 President. Part II. " On the structure of the Shell in the several 

 families and genera of Mollusca *." 



The author here gives in detail the results of his inquiries into 

 the combinations of the component elements of shell as they are 

 met with in the several families and genera of the Mollusca ; and 

 considers all these results as tending to establish the general propo- 

 sition, that where a recognizable diversity presents itself in the ele- 

 mentary structure of the shell, in different groups, that diversity af- 

 fords characters which indicate the natural affinities of the several 

 genera included in those groups, and which may therefore be em- 

 ployed with advantage in classification, and in the recognition and 

 determination of fossils. 



June 15. — The following papers were read, viz. — 



1. "On the supposed developement of the Animal Tissues from 

 Cells." By James Stark, M.D., F.R.S.E. Communicated by James 

 F. W. Johnston, Esq., M.A., F.R.S. 



The author controverts the prevailing theory of the developement 

 of animal tissues from cells, and denies the accuracy of the micro- 

 scopical observations on which that theory is founded, as regards the 

 anatomy of the adult as well as of the foetal tissues. He asserts that 

 at no period of foetal life can rows of cells be discovered in the act 

 of transformation into muscular fibres: and he denies that these 

 fibres increase either in length or in thickness by the deposition of 

 new cells. He contends that the ultimate filaments of muscles, as 

 well as all the other tissues of the body, are formed from the fibri- 

 nous portion of the blood, which is itself composed of globules that 

 are disposed to cohere together, either in a linear series, so as to 

 form a net-work of fine filaments, or in aggregated masses of a form 

 more or less globular, composing what have been termed fibrinous 

 corpuscles. These corpuscles have been considered to be the nuclei 

 of cells ; but the author regards them as being merely accidental 

 fragments of broken-down tissues, adhering to the filaments, and 

 noways concerned in their developement. The more regularly dis- 

 posed granules, which are observed to occupy the spaces intervening 

 between the filaments composing the ordinary cellular tissue, he 

 considers as being fatty matter deposited within these spaces. He, 

 in like manner, regards the observations tending to show the cellular 

 origin of the fibrous, cartilaginous, and osseous tissues, as altogether 

 fallacious ; and maintains that the cells, which these animal textures 

 exhibit when viewed under the microscope, are simply spaces occur- 

 ring in the more solid substance of these structures, like the cavities 

 which exist in bread. These views are pursued by the author in 

 discussing the formation of the skin, the blood-vessels, and the 

 nerves, and in controverting the theory of secretion, founded on the 

 action of the interior surfaces of the membranes constituting cells. 



[* For a notice of Part I. of Dr. Carpenter's paper, see our preceding 

 volume, p. 484.] 



