66 THE GENERAL MORPHOLOGY OF THE PLANT. 



soon separates the whole inclosed contents into two parts ; a layer 

 of cellulose is at the same time deposited on the surface, and 

 thus two new cells are produced (Fig. 64), which usually subdi- 

 vide each into two (Fig. 65). Four new cells are thus formed 

 within a mother-cell ; and the latter is destroyed in the process, 

 all its living contents having been employed in the formation of 

 the progeny, and its effete wall is obliterated by softening or de- 

 cay, or by the enlargement of the contained cells. Thus this sim- 

 plest vegetation goes on, from generation to generation. The sof- 

 tened remains or products of the older cells often accumulate and 

 form a gelatinous stratum or nidus, in which the succeeding genera- 

 tions are developed, and from which they doubtless derive a part 

 of their sustenance, just as a tufted moss is nourished in part 

 from the underlying bed of vegetable mould which is formed of 

 the decayed remains of its earlier growth. One step in advance 

 brings us to 



96. 2d, Plants of a Single Elongated Cell; that is, of a cell 

 which grows on in one direction, but without branching. Such 



plants answer to cells of 

 prosenchyma, or to vessels 

 (52, 57). For an example 

 we may take any species 

 of Oscillaria (Fig. 66) ; a 

 form of aquatic vegetation 

 of microscopic minuteness, 

 considered as to the size of 



the individuals, but which rapidly multiply in such inconceivable 

 numbers, that, at certain seasons, they sometimes color the surface 

 of whole lakes of a green hue, as suddenly as broad tracts of 

 alpine or arctic snow are reddened by the Protococcus.* 



97. 3d, Plants of an Elongated and Branching Cell. Some 

 elongated cells in vegetable tissue fork as they elongate, and be- 

 come branched ; as is seen in Fig. 15. Several plants consist of 

 individual cells of this kind ; as, for example, the species of Vau- 

 cheria, which form one kind of the delicate and flossy green 



* If the transverse markings of Oscillaria arise from imperfect partitions, 

 then the plant corresponds to the duct (58). 



FIG. 66. Two individuals of Oscillaria spiralis, magnified ; one of them with one extremi- 

 ty cut off. 



