MICROSCOPIC FORMS OF VEGETABLE LIFE. 



notwithstanding that every cell is but a repetition of every other, and is 

 capable of living independently if detached, so as still to answer to the 

 designation of a ' unicellular ' or single-celled Plant. These different 

 conditions we shall find to arise out of the mode in which each particular 

 species multiplies by binary subdivision ( 226) : for where the cells of 

 the new pair that is produced within the previous cell undergo a complete 

 separation from one another they will henceforth live independently; 

 but, if, instead of undergoing this complete fission, they should be held 

 together by the intervening gelatinous envelope, a shapeless mass results 

 from repeated subdivisions not taking place on any determinate plan; 

 and if, moreover, the binary subdivision should always take place in a 

 determinate direction, a long narrow filament (Fig. 145, D), or a broad 

 flat leaf -like expansion (G), may be generated. To such extended fabrics 

 the term ' unicellular ' plants can scarcely be applied with propriety; 

 since they may be built-up of many thousands or millions of distinct 

 cells, which have no disposition to separate from each other spontane- 

 ously. Still they correspond with those which are strictly unicellular, as 

 to the absence of differentiation either in structure or in actions between 

 their component cells; each one of these being a repetition of the rest, 

 and no relation of mutual dependence existing among them. And all 

 such simple organisms, therefore, may still be included under the general 

 term of PROTOPHYTES. 



228. Excluding Lichens, for the reasons to be stated, hereafter ( 325), 

 Botanists now rank these Protophytes under two series: Algae , which 

 form chlorophyll, and can support themselves upon air, water, and min- 

 eral matters; and Fungi, which, not forming chlorophyll for themselves, 

 depend for their nutriment upon materials drawn from other organisms. 

 Each series contains a large variety of forms, which, when traced from 

 below upwards, present gradationally increasing complexities of struc- 

 ture; and these gradations show themselves especially in the provisions 

 made for the Generative process. Thus, in the lowest, a ( zygospore ' is 

 produced by the fusion of the contents of two cells, which neither present 

 any sexual difference, the one from the other, nor can be distinguished 

 in any way from the rest ( 229). In the following stage, while the * con- 

 jugating' cells are still apparently un differentiated from the rest of the 

 structure, a sexual difference shows itself between them; the contents of 

 one cell (male) passing over into the cavity of the other (female), within 

 which the ( zygospore' is formed ( 235). The next stage in the ascent 

 is the resolution of the contents of the male cell into motile filaments 

 ('antheroida'), which, escaping from it, move freely through the water, 

 and find their way to the female cell, whose contents, fertilized by mix- 

 ture with the material they bring ( 249), form an 'oospore.' In the 

 lower forms of this stage, again, the generative cells are not distinguish- 

 able from the rest, until the contents begin to show their characteristic- 

 ally sexual aspect ( 253); but in the higher they are developed in special 

 organs, constituting a true ( fructification ' ( 259). This must, how- 

 ever, be distinguished from organs, which, though commonly spoken of 

 as the ' fructification/ have no real analogy with the generative apparatus 

 of Flowering-plants; their function being merely to give origin to goni- 

 dial 1 cells or groups of cells, which simply multiply the parent stock, in 



1 The term Gonidia, originally applied to certain green cells in the Lichen- 

 crusts, that are capable, when detached, of reproducing the vegetative portion 

 of the Plant ( 325), has latterly come into use as a designation of the non-sexual 

 spores of Cryptogamia generally, which it is very important to discriminate from 



