THE CELL WALL 49 



on tlic influt'iice of different ions on emnlsion formation and mem- 

 brane l)ermeabilit3^•'''" The influence of inorganic salts on the swell- 

 ing of tissue colloids is also tliscussed from another standpoint by M. 

 H. Fischer in his work on ''Edema." In any event it is important 

 ior the cell that the proportion of the inorganic constituents be main- 

 tained in rather constant conditions of quality and ([uantity. 



The various secretory granules, fat-droplets, pigment-granules, 

 gh'cogen granules, keratin, etc., that may lie in the cytopla.sm, are 

 inconstant constituents, varying with different cells, and under varj^- 

 iug conditions in the same cells, and lie beyond the scope of our dis- 

 cussion of the general coin])osition of the cell. According to Ruzicka ^"^ 

 there is contained in all cells, both in nucleus and cytoplasm, an in- 

 soluble substance which corresponds structurally to the "plastin" of 

 the cytologists, and chemically is related to the reticulins and other 

 albuminoids; this he looks upon as the ground substance of the cells, 

 corresponding to the albuminoid ground substance of stroma of or- 

 ganized tissues. 



Certain of the granulations observed in the cj'toplasm of cells seem 

 to be definite, constant structures of the living protoplasm, and these 

 are now called mitochondria, which term includes many forms of 

 granules described under various names.^"" Their solubility and 

 staining reactions suggest that they contain phospholipins, perhaps 

 associated with proteins. Their functional importance is indicated 

 by the fact that usually their number varies directly with the meta- 

 bolic activity of the cells, and they may be related to histogenesis. 



Other histological cellular structures also permit of more or less 

 satisfactory identification by microchemical methods, and Unna^^*" 

 especially has contributed to this field. By staining sections with 

 dyes of varying reaction, after extracting the sections with various 

 solvents, he has obtained evidence of the chemical nature of some of 

 the cell structures, although it is by no means certain that the con- 

 clusions drawn will all be verified. In the nucleolus he finds a sub- 

 stance resembling globulin, the granuloplasm of the cell body he re- 

 gards as an albumose, the spongioplasm as histone, mast cell granules 

 as mucin or mucoid substances. Nissl bodies he holds to be albumose, 

 altho others have believed them to be nucleins.^^'^ 



THE CELL-WALL 37 



The cell membrane in most animal cells is inconspicuous struc- 

 turally, but in discussing osmosis it was sho^^^l that it is of the greatest 



35a Jour. Physical Chem., 1916 (20), 407. 

 scArch. f. Zellforsch., 1008 (1), 587. 



36a See review bv Cowdrv. Amer. Jour. Anat., 1916 (19), 42.3. 

 sfibSee review bv Gans, "Dent. med. Wooh., 191.3 (39), 1944. 

 36c See Unna, Berl. klin. Woeh.. 1914 (51), 444: :Miihliiiann. Arch. mikr. Anat.. 

 1914 (85). 361. 



3" See Zangger, '"Ueber ^lembranen und IMcjnljrancnfunktionen," Krgcbiiisse d. 

 4 



