PLANTS OF A SINGLE CELL. 65 



preceding chapter (26-35). For in them vegetation is reduced 

 to its simplest terms : the plant and the cell are here identical. 

 The cell constitutes an entire vegetable without organs, imbibing 

 its food by endosmosis (37) through its permeable walls, assimi- 

 lating this food in its interior, and converting the organizable prod- 

 ucts at first into the materials of its own enlargement or growth, 

 or finally into new cells which constitute its progeny. Thus we 

 have an epitome of all that is essential in vegetation, even on the 

 largest scale, namely, the imbibition of inorganic materials ; its 

 assimilation ; its application to the growth of the individual, or nu- 

 trition, and the formation of new individuals, or reproduction. 

 But even while thus organically simple, the plant is not restricted 

 to one monotonous pattern. On the contrary, different species, 

 each in its own uniform manner, develope the cell and give rise 

 to their progeny in all the various ways that have been mentioned 

 when describing the forms and the development of cells. The 

 simplest case is that of 



95. 1st, Plants of a Single Globular Cell; that is, of a cell 

 which grows equally in every direction, and therefore is neither 

 elongated nor branched. Of this, the microscopic plant known as 

 giving rise to the phenomenon of red snow (but which also occurs 

 on damp earth, &c.) furnishes a good illustration. Each individ- 

 ual is a single cell (Fig. 61), which quickly attains its growth, and 

 produces (by original cell-formation, it is 

 thought) a considerable number of minute 

 free cells in its interior. The mature 

 mother-cell now decays ; and the new 

 generation it contained enlarge into simi- 

 lar cells or plants, which give rise to their 

 progeny and perish in their turn. Some 

 other globular one-celled plants (like Chro- 

 ococcus, Fig. 63), are very similar, except that they propagate by 

 division of the whole contents, and finely illustrate that general 

 process of free cell-multiplication (37). The layer of protoplasm 

 which lines the cell-wall forms a constriction in the middle, and 



FIG. 61. Several individuals of the Red-anow Plant (Protococcus nivalis), magnified. 62. 

 An individual highly magnified, showing more distinctly the new cells or spores formed with- 

 in it. 



FIG. 63. An individual of Chroococcus rufescena, after N'igeli, much magnified. 64. A 

 more advanced individual, with the contents forming two new cells by division. 65. Another, 

 with the contents divided into four new cells. 



6* 



