BOOK I 

 MORPHOLOGICAL BOTANY 



CHAPTEE I 



GENEEAL MOEPHOLOGY OF THE PLANT 



The simplest plants, such as the Bed Snow (Protococcus), or 

 Pleurococcus, consist of a single membranous sac, or cell as it is 

 termed, which in form is more or less spherical or oval. New 

 plants are formed by the division of this cell into two, sometimes of 

 equal, sometimes of unequal dimensions. In Protococcus the cells 

 separate almost as soon as formed, while in Pleurococcus they 

 remain bound together for a longer or shorter period by an en- 



FiG. 1. Fig. 2. 



Fiff. 1. Pleurococcus vulgaris ; cells dividing ( x 600). 

 Fig. 2. Portion of a filament of Oscillaria ( x 750). 



vironing capsule of gelatinous matter, the result of a modification 

 of the cell- wall, or limiting membrane. In plants immediately 

 above these in point of complexity we find the cells still all alike, 

 but instead of being separated and each becoming a distinct plant, 

 or forming a small colony of cells, they are joined end to end and 

 form a many-ceUed filament which is either straight or vari- 

 ously curved, as in Oscillaria (fig. 2). The most lowly of these 

 plants — so far at least as is known — multiply by division of 

 their cells only ; but a little higher in the scale we meet with 



B 2 



