MICROSCOPIC FORMS OF VEGETABLE LIFE. 233 



2), which is not uncommon in collections of rain-water. Not only lias this 

 Protophyte, in its motile-condition, been very commonly regarded as an 

 Animalcule, but its different states have been described under several differ- 

 ent names. In the first place, the color of its cells varies considerably; 

 since, although they are usually green at the period of their most active 

 life, they are sometimes red; and their red form has received the distin- 

 guishing appellation of Hcematococcus. Very commonly the red-coloring 

 matter forms only a central mass of greater or less size, having the appear- 

 ance of a nucleus (as shown at E) ; and sometimes it is reduced to a single 

 granular point, which has been erroneously represented by Prof. Ehren- 

 berg as the eye of these so-called Animalcules. It is quite certain that 

 the red coloring-substance is very nearly related in its chemical character 

 to the green, and that the one may be converted into the other : though 

 the conditions under which this conversion takes place are not precisely 

 known. In the still form of the cell, with which we may commence the 

 history of its life, the endoplasm consists of a colorless protoplasm, 

 through which red or green-colored granules are more or less uniformly 

 diffused: and the surface of the colorless protoplasm is condensed into 

 an ectoplasm, which is surrounded by a tolerably firm layer, consisting of 

 cellulose or of some modification of it. Outside this (as shown at A), 

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

 aqueous fluid; this, however, may be altogether wanting. The multipli- 

 cation of the 'still ' cells by subdivision takes place as in Palmoglcea; the 

 endoplasm first undergoing separation into two halves (as seen at B), and 

 each of these halves subsequently developing a cellulose envelope around 

 itself, and undergoing the same division in its turn, O.'hus, 2, 4, 8, 1C 

 new cells are successively produced; and these are sometimes set-free by 

 the complete dissolution of the envelope of the original cell; but they are 

 more commonly held together by its transformation into a gelatinous in- 

 vestment, in which they remain imbedded. Sometimes the endoplasm 

 subdivides at once into four segments (as at D), of which every one forth- 

 with acquires the characters of an independent cell; but this, although an 

 ordinary method of multiplication among the * motile' cells, is compara- 

 tively rare in the ' still ' condition. Sometimes, again, the endoplasm of 

 the 'still' form subdivides at once into eight portions, which, being of 

 small size, and endowed with motile power, may be considered as zoospores. 

 It is not quite clear what becomes of these; but there is reason to 

 believe that some of them retain their motile powers, and develop them- 

 selves into the ordinary ' motile ' cells; that others produce a firm cellu- 

 lose envelope, and become 'still' cells; and that others (perhaps the 

 majority) perish without any further change. 



231. When the ordinary self -division of the 'still' cells into two seg- 

 ments has been repeated four times, so as to produce 16 cells and some- 

 times at an earlier period the new cells thus produced assume the 

 * motile 'condition; being liberated before the development of the cellulose 

 envelope, and becoming furnished with two long vibYatile flagella, which 

 seem to be extensions of the colorless protoplasm-layer that accumulates 

 at their base so as to form a sort of transparent beak (H). In this condi- 



Nat. Curios." (Bonn, 1850), Tom. xxii.; of which an abstract by Mr. George Busk 

 is contained in the " Botanical and Physiological Memoirs" published by the Ray 

 Society for 1853. 



