88 ALGJE, 



other porous bodies. It consists of very minute oval 

 green cells,, with thick walls, and imbedded in the 

 ends of prolongations of a gelatinous matrix. 



Palmel'la cruerita (PI. VI. fig. 25) forms a portwine- 

 red layer at the bottom of damp walls or on the 

 ground. It is composed of pale red cells, imbedded 

 in no definite order in a colourless gelatinous matrix. 

 The cells are filled with red granules, and are often 

 found undergoing division. 



PI. VI. fig. 19 represents a species of Glceocap'sa, 

 in which the cell- envelopes do not soften and unite to 

 form a gelatinous matrix, as in Palmetto, and other 

 members of the family, but are persistent. This 

 species occurs in fresh water containing Confervae. 



CHARA'CE^E. This family consists of the single 

 genus Chdra, the systematic position of which is not 

 agreed upon by authors ; as however its structure will 

 be better understood after what has been gone over, 

 it may be conveniently considered here. 



There are several species of Chara, the one illus- 

 trated, Char a vulgdris (PI. VI. fig. 21), being com- 

 monly found in ditches and pools. It consists of long 

 main stems, often a foot in length, which are branched, 

 and surrounded at tolerably regular intervals by whorls 

 of branchlets. In some species, the stems and branches 

 consist simply of elongated cells, arranged end to end ; 

 while in others, of which Chara vulgaris is one, the 

 central cells are surrounded by a number of narrower 

 spirally arranged cells, forming an outer coating. 



The Charse have long formed interesting micro- 

 scopic objects, on account of the circulation of the 

 protoplasm being visible in the cells, as in the hairs 

 of Tradescantia. This is best seen in those species 

 in which the outer layer of cells is absent from the 

 stems, and which were formerly arranged in a sepa- 

 rate genus (Nitella) . But it may also be seen in the 

 stems and especially the young branchlets of any of 

 the other species ; and as the granules of the proto- 



