86 ALGM. 



grass-green layer, consisting of somewhat rigid curled 

 filaments. The endochrome is usually broader than 

 long ; and the cells of the filaments are often found 

 empty, the endochrome having escaped in the form 

 of gonidia. 



PL VI. fig. 6 represents a species of Bacterium 

 which is not uncommon in decomposing vegetable 

 liquids ; the filaments are short, curved, pointed at the 

 ends, and have four joints. 



Fig. 26 represents a Schizogonium, found upon 

 damp paths. The filaments resemble those of Lyngbya, 

 but are united in pairs. 



Fig. 3 represents a filament of a Vlothrix, which 

 is common in freshwater pools, showing the curious 

 manner in which the endochrome is arranged in the 

 cells, forming bands partially lining the cell-walls. 



NOSTOCHA CEM. Two species of the typical genus 

 Nos'toc will serve to represent this family. Nos'toc 

 commune is found on damp ground or in ponds, and 

 forms to the naked eye firmish, olive-green, skin-like 7 

 plaited masses, an inch or more in diameter. Under 

 the microscope it is seen to consist of numerous 

 beaded fibres, imbedded in worm-like gelatinous 

 sheaths ; these are curved and interwoven to form the 

 compound mass. In the middle of many of the fila- 

 ments is an enlarged colourless cell, called the vesi- 

 cular cell, which is related to the reproduction, but 

 in a manner not yet determined. 



Nostoc minutissimum (PL VI. fig. 4) forms solid 

 gelatinous bluish-green masses, varying in size from 

 a pin's head to a pea; it is found upon unhealthy 

 water-plants kept in glass vessels. The component 

 filaments are very slender, wavy, and the sheaths 

 often have a brownish tinge. 



ULVACE.E. These Algae are mostly marine some, 

 however, being found in brackish or fresh water, or 

 on damp ground, thatch, moss, &c. They are gene- 

 rally of considerable size, forming flat or tubular 



