210 Dr Barry on Fissiparous Generation. 



as regards other points connected with this globule, Professor 

 Schleiden and myself are not agreed. 



15. Schleiden considers the substance of the *' cytoblast'' to 

 be deposited around the globule.* According to my observa- 

 tions, on the contrary, a globule of the substance in question 

 — ^hyaline — appropriates to itself nem matter ; the new matter 

 is not deposited around the globule, but the globule, as it ap- 

 propriates the new matter, becomes transformed into a disc 

 or discoid body corresponding to the *' cytoblast'' of Schleiden. t 

 A pellucid substance then begins to make its appearance 

 within the discoid body. This pellucid substance (hyaline) is 

 not, as supposed by Schleiden, the identical previously exist- 

 ing globule ; it results from the appropriation of new matter 

 by that globule, and now comes into view at a certain part of 

 what was that globule4 



16. It appears to me then, that the originally independent 

 globule of hyaline is the true cell-germ, — the " cytoblast" of 

 Schleiden representing only a stage in the formation of the 

 cell. 



17. The membrane of the cell§ is of comparatively small 



* The following is the substance of a statement made by Professor Valentin, as 

 briefly expressing the views, on this subject of Shleiden, Schwann, Miiller, Henle, 

 and himself; and as being descriptive of the first formation of the elements of tis- 

 sues : — In a fluid, says he, there are precipitated granules, which are nucleoli ; 

 Qg-ound the nucleolus there is deposited a finely granular substance, by which there 

 is formed the nucleus (" cytoblast") ; and around the nucleus there is formed the 

 membrane of the cell. The principle of formation of the nucleus around the nu- 

 cleolus, is essentially the same as that of the cell around the nucleus. Valentin 

 concludes that this process may be described by the expression, heterogeneous 

 ciVcMmposition. 



t The terms " Cytoblast" and " Nucleus of the Cell," seem to have been used in- 

 discriminately. It is my opinion that they are very different things, and that it 

 is important to point out the difference. The "cytoblast" exists before the 

 celL The '* nucleus of the cell" is sometimes that which remains of the " cyto- 

 blast" after the membrane of the cell is formed ; and sometimes — the remains 

 of the " cytoblast" having been entirely resolved into the contents of the cell — the 

 " nucleus'' is a subsequent formation in the same part. It is then the*' nucleolus" 

 enlarged, i, e., the ^' hollow nucleus" of authors ; this hollow nucleus being no 

 other than the hyaline in the course of appropriating to itself new matter. 



X When two or more nucleoli are present, they result from a divisioa of the pel- 

 lucid substance — hyaline — into as many parts. (Par. 13). 



§ Formed, according to my observations, of the outer part of the '* cytoblast,'* 

 and not around it. (Phil. Trans., 1841, p. 209). 



