THE NUCLEATED CELL. 493 



texture, it uniformly consists of a non-nitrogenized body, gummy, amy- 

 laceous, or ligneous. Indeed, though the vegetable cell is usually said 

 to have two concentric investitures, the nitrogenized primordial utricle 

 and the non-nitrogenized wall, it is more exact to describe the latter as 

 consisting of several pellicles, which have been generated in succession 

 from the outside surface of the utricle, and these differ from one another 

 in their physical qualities, according as they are nearer to the surface of 

 the utricle or nearer to the general exterior, recalling, in this respect, the 

 analogous condition of the cuticle under circumstances that are some- 

 what parallel. 



Within the primordial utricle, the cell contents present themselves of 

 a different nature and different form, according as the species of the cell 

 may be. In different cases they are colored of various tints, and are of 

 various consistency, more solid or more liquid. To the cell-contents the 

 convenient designation of endochrome is given. This interior content is 

 not to be understoodas having a homogenous constitution, since sometimes 

 even its colored portions are separated out and arranged in dots or spiral 

 lines, which are very distinct from the remaining uncolored material. 



The active portion of such a cell consists of the utricle and endochrome 

 conjointly, the cell wall only discharging a mechanical office. In the 

 simple cell, all parts of the utricle appear to be endowed with equal pow- 

 er for carrying on the functions of the organism. 



But in those cells which possess a nucleus, the energy is no longer dif- 

 fused with uniformity, the nucleus concentrating much of , 

 the power in itself, and serving as a centre of activity. Its activity of its 

 nitrogenized constitution indicates that it is in relation with nucleus - 

 the primordial utricle, and not with the cell wall ; a conclusion which is 

 corroborated by its physiological activity, as also by the fact that in those 

 nucleated cells which exhibit currents, the nucleus appears to be the 

 starting-point from which they diverge in various directions. 



There are subordinate species of cells, as the spiral and the dotted. 

 These exhibit points of re-enforcement or thickening, such Subordinate 

 as the appearance of a thread wound spirally, or in dots here forms of cells - 

 and there on the interior of the wall. There would seem to be a tend- 

 ency during the development of a cell for these parts to assume a spiral 

 arrangement. Even the endochrome shows this peculiarity, the green 

 material being often arranged in a spiral course on the interior of the cell. 



Thus constituted, each cell runs through a definite cycle or career, hav- 

 ing its moment of birth, its period of maturity, its time of death. Dur- 

 ing its mature life it discharges with activity the special function to which 

 it is devoted, but in so doing becomes eventually worn out and old. 

 The period of activity of cells of different species is very different, some 

 passing away quickly, and others having a longer duration. 



