CELL. 



[ 142 ] 



CELL. 



the space ; as in the case of the cells of a 

 Polype, or Polyzoon, the cells of a sponge, 

 &c. 



BiBL. Treatises on Physiologif ; Schwann, 

 Einstimmioni (St/d. Soc.) ; id. Waffner's 

 Physiol. ; Valentin, Phys. ; KoUiker, Ge- 

 webelehre d. Menschen (and the Bibl. there- 

 in) ; Siebold, Zeitschr. f. ivissens. Zool. i. 

 p. 270; Ptollett, Sf richer' s Handbuch (Syd. 

 Soc.) i. ; Frey, Histolor/ie, and the Bihl.) ; 

 Cohnheim, Virchoio's Archiv, xl. ; Reck- 

 linghausen, ibid, xxviii. ; Weissmann, 

 Zeitsch. f. rat. Med. 3rd ser. xv. ; Klein, 

 Qu. Mie. Jn. 1878 and 1879, and Hist. ; 

 Carpenter, Phys. ; Strassburger, Zeltenbil- 

 dung, 1880; and the Bibl. of Tissues. 



CELL, Animal, artificial formation of. — 

 When oil is immersed in a liquid containing 

 albumen, it becomes surrounded by a layer 

 of coagulated albumen, forming a cell ; and 

 this cell will exhibit the phenomena of en- 

 dosmose and exosmose in the same manner 

 as any natural cell. The same phenomenon 

 has been observed with metallic mercury and 

 albumen, chloroform and albumen, chloro- 

 ftjrm and chondrine, &c. It has not yet 

 been satisfactorily explained. The natural 

 formation of cells has been supposed to be 

 produced by this method ; but it appears 

 inapplicable to the purpose, as the nuclei or 

 masses of blastema, around which natural 

 cells are formed, do not consist of fat. 



See Concretions. 



Bibl. Ascherson, Miiller's Archiv, 1840, 

 p. .44, &c. ; Wittich, De hymenogonia albu- 

 minis, Eegiomout. 1850 ; Harting, Neder. 

 Lane. Sept. 1851 ; Melsens, Bull, de VAcad. 

 de Belg. 1850 ; Panum, Archiv f. path. Ati. 

 iv. 2 ; Bennett, JEd. Mn. Jn. viii. 16G ; Kiil- 

 liker, Geweb. d. Mensch. 10 ; Schmidt, 

 Taylor's Scientific Memoirs, v. 10. 



CELL, Vegetable. — The definition of 

 the term cell in Tegetable anatomy, ordina- 

 rily adopted, is, a closed sac composed of an 

 (originally) imperforate membrane formed 

 of the chemical substance called cellulose, 

 this membrane enclosing more or less fluid 

 contents so long as the ceU retains its vi- 

 tality. All the solid permanent structures 

 of plants are formed of cells answering to 

 this character, the differences of the full- 

 grown tissues depending upon peculiar 

 modifications and alterations of the original 

 cells. In animal structures, the term cell 

 is commonly applied, not only to structures 

 really analogous to the cells of plants, but 

 also structures analogous to the contents of 

 the true cellulose plants, which, however, 



are indeed in all cases the important vital 

 parts of the structure. All young vegetable 

 cells contain a quantity of semiiiuid nitro- 

 genous formative substance called proto- 

 plasm, which may be chiefly adherent as a 

 thickish and more or less continuous layer 

 on the inside of the cellulose wall, forming 

 a kind of lining to it, and therefore en- 

 closing all the rest of the contents, in which 

 case it forms the primordial utricle of Mohl ; 

 or this dense protoplasm may fill up the 

 whole cavity of the cell as a gelatinous 

 mass. Or the gelatinous mass of proto- 

 plasm may emerge from the cellulose sac, 

 with a definite form and organization, fur- 

 nished with cilia enabling it to move freely 

 in water ; and here the protoplasm presents 

 itself as independent, and indeed as the pri- 

 mary element of all cellular tissue : it occurs 

 in this condition in the zoospores of the 

 Confervoid Algne. These free bodies, de- 

 void at first of a cellulose wall, are evidently 

 analogous to the corpuscles of ' sarcode ' 

 constituting certain animals, such as Amoeba, 

 while the cartilage-cells &c. of animals are 

 analogous to the cellulose sacs of plants. 



In this work, then, the word cell, as ap- 

 plied to organic structures, is always used 

 in its ordinary sense. Hiickel's unnecessary 

 terms Cytode for the simple protoplast, and 

 Cell for the nucleated protoplast, are ignored 

 in botanical works. 



Form. — Cells may present almost every 

 possible modification of form ; and this 

 depends on two sets of conditions — the ori- 

 ginal development and shape, and the mode 

 of growth and expansion. It is frequently 

 stated that the primary form of all vege- 

 table cells is that of a sphere, or at all events 

 that this is the type, from which all the others 

 must be considered deviations. This is true 

 only so far as it is intended to signify that 

 most cells which originate free in the midst 

 of fluid, suffering no external compression, 

 have a globular form ; and that in numerous 

 cases where cellular tissues are very lax and 

 free to expand in all directions, the compo- 

 nent cells acquire a globular form during 

 the enlargement to their full size. But in a 

 very large majority of cases the cells do not 

 originate in a free condition, they are pro- 

 duced by subdi\ision of older cells, and 

 consequent^, when first developed, they 

 have the shape of the half, the quarter, or 

 whatever segment it may be. of the parent- 

 cell ; moreover, in a majority of these cases 

 the mode of expansion also depends upon a 

 special law of the particular tissue, or even 



