218^ Dr Barry on Fissiparous Genera Hon. 



tremely minute discs, which in like manner coalesce ;* there 

 being left here and there a centre for the origin and assimi- 

 lation of new substance, in order to the thickening or other 

 modifications of the membrane. In Ehrenberg's Ophrydium 

 is to be seen, I think, a membrane forming in this manner, 

 and dividing at one extremity into cilia, destined to surround 

 the future " mouth." Delineations given by myself of the 

 epithelium-cylindert render it extremely probable that here 

 the cilia arise in the same manner. 



68. The division and coalescence of discs now mentioned 

 lead to assimilation ; so that the structure into which the 

 discs have become converted, at last consists of a substance 

 more or less like that of the cell-nucleus or hyaline itself. 

 These remarks are applicable to other structures besides 

 membrane, — for instance, to cartilage and fibre ; and the facts 

 above mentioned regarding muscle (par. 48-51) seem to in- 

 dicate the mode in which, by means of continually enlarged 

 and then dividing nuclei (portions of hyaline), the muscular 

 fibrilj is nourished and renewed. 



69. The chorion affords, perhaps, the best example I have 

 met with, of membrane forming by the assimilative process 

 now described. § For the formation of this structure, blood- 

 cells send out processes in several directions ; the processes 

 interlace, and the pellucid nuclei of the blood-cells follow the 

 direction of (that is to say, portions of them pass into) the in- 

 terlacing processes. In short, there takes place so extended 

 a division and sub-division of the nuclei or hyaline, that the 

 chorion itself is scarcely less pellucid than the nuclei which 

 form it. The albumen seems to pass through, or rather to 

 be formed by, an assimilation of the same kind. 



70. The cilia-bearing network of the parent-wall in the 

 Yolvox appears to have an origin not essentially differing 

 from that which gives origin to membrane. Indeed, I think 

 it not improbable that the membranes of many cells — ^for in- 

 stance those of the mammiferous germ in the oviduct — may 

 really have a structure comparable to that network of the 



* In some instances first forming a spiral thread, 

 t Phil. Trans. 1841, Plate XXI. figs. 96-100. 

 X And perhaps fibre in general. 



§ See Phil. Trans. 1840, Plate XXVIII. figs. 252,253, p. 545. par. 372. Plate 

 xxix. figs. 0, 7, 0. p. COO. 



