VOLVOCINE.E. 83 



which contains many species of Epithemia, Navicula, 

 Pinnularia, &c. These may be procured from Mr. 

 Norman, 178 City Road, or from the microscope- 

 makers. 



VOLVOCIN'EJE. The Volvocinese are inhabitants of 

 clear fresh-water pools, on heaths and bogs. They 

 are very minute, of a rounded or plate-like (tabular) 

 form, of a green colour, and are pretty readily distin- 

 guished from most of the other Algse by their free 

 motion ; for they swim about in the water like animals, 

 as which they were formerly considered. They consist 

 usually of groups of thick- walled soft cells, each being 

 furnished with one or two cilia, by means of which 

 the movement of the compound bodies is produced. 



In the beautiful Volvox globdtqr (which is not 

 uncommon) the cells form a hollow sphere (PL VI. 

 fig. 18), studded with exceedingly minute green spots 

 or zoospore-like bodies, representing the green endo- 

 chrome of the component cells, and from each of 

 which very fine radiating lines extend, so as to give 

 the surface a netted appearance ; the lines consisting 

 of delicate processes of the endochrome, which may 

 be compared with those existing in the cells of the 

 hairs of Tradescantia. In the interior of the parent 

 globes are often seen several young organisms, usually 

 eight, of a deep green colour ; these escape by the 

 rupture of the parent, so as to form independent 

 beings. Sometimes they are found of a yellow 

 colour, and furnished with a thick transparent coat ; 

 these are called ' ' resting spores," as they remain for 

 some time before undergoing their full development. 



The cilia of Volvox, of which there are two to each 

 of the component cells, are difficult to detect ; they 

 are best seen when the organism is dried without a 

 cover, or after moistening them with a little solution 

 of iodine, which dyes them brown. 



Synura volvox (PL VI. fig. 13) is a still more 

 minute member of this family, and is often found 



