190 



THE MICROSCOPE. 



loped, more especially with a view to the dispersion of the 

 species. 



One of the most remarkable of the lower forms of 

 vegetable life is the Protococcus pluvialis, fig. 105, not 

 uncommon in collections of rain-water, constituting the 

 genus Chlamydomonas of Professor Ehrenberg, and the 

 curious motile organs of which induced him to regard 

 them as animalcules. Dr. Cohn describes the early form 

 of the cell as a mass of endochrome, consisting of a 

 colourless protoplasm, through which red or green-coloured 

 granules are more or less uniformly diffused : on the sur- 



Fig. 105. Vegetable Cell Development. (Protococcus pluvialis.) 



A, division of a simple cell into two, each primordial vesicle having developed a 

 cellulose envelope around itself; B, Zoospores, after their escape from the 

 cells ; c, division of an encysted cell into segments ; D, division of another 

 cell, with vibratile filaments projecting from cell-wall ; E, an encysted cell ; 

 p, division of an encysted cell into four, with vibratile filaments projecting; 

 G, division of a cell into two. 



face of this endochrome the colourless protoplasm is con- 

 densed into a more consistent layer, forming an imperfect 

 " primordial utricle ; " and this is surrounded by a tolerably 

 firm layer, which seems to consist of cellulose, or of some 

 modification of it. Outside this again, as in fig. 105 E, 

 when the still-cell is formed by a change in the condition of 

 the cell that has been previously " motile/' we find another 

 envelope, which seems to be of the same nature, but which 

 is separated by the interposition of fluid. The multipli- 

 cation of still- cells, by self-division, takes place as in the 

 previous instance; the endochrome, enclosed in its pri- 

 mordial utricle, first undergoes separation into two halves, 



