THE CELL 



THE CELL 



General Statements. A generalized cell is of spheroidal shape (un- 

 modified by pressure) and contains certain 'organs' and a variety of fun- 

 damental and secondary elements (Fig. 4). A cell (or protoplast; 

 Hanstein) is a mass of protoplasm endowed with vital properties. The 

 confines of such a cellular mass of protoplasm exist in a cell meinbranr. 



* ' i >.... \ v \ fTfsSK! 1 , " -\ 



yTr--/^T?-Kv\?%---:s 



S*r^>t-^>< v >Mi 



v^33kg^5w w^n^-. 



r \%WK Ml X>^-:; 



V.m^fe^W;^i^<%^-:y 



X . -*. :;,..."/.. : . < f ..**.-/ -,' \ .-.-* * . S 



FIG. 4. A GENERALIZED CELL. 



a, exoplasm; fe, endoplasm; c, spongioplasm; d, hyaloplasm; e, microsomes; /, 

 chromidia; g, centrosome (centriole) ; /;, centrosphere, surrounded by astrosphere; i, cell 

 membrane; j, deutoplasmic granule; k, fluid vacuole, or oil drop; I, mitochondria or 

 plastosomes; m, nuclear membrane; n, nucleolus; o, linin; p, karyosome; q, chromatin 

 (net knot); r, foreign inclusions, pigment, etc. (metaplasm). 



This represents a differentiation product of protoplasm; when robust 

 as in plant cells, it forms a cell wall. In certain cells, e.g., white blood- 

 cells, it is apparently lacking; however, in these so-called naked cells the 

 peripheral layer of protoplasm is more condensed and most probably 

 subserves the osmotic function of a distinct membrane. In fact, the 

 surfaces of protoplasm possess the properties of semipermeable mem- 

 branes, probably lipoid in nature. An essential organ of the cell is the 

 nucleus. It is trophic in function, the center of oxidation processes. 

 In certain protozoa this is represented by scattered nuclear materials 



