316 



BOTANY. 



phycocyanine — and a less soluble one— pfiycoxanlhine.* 

 Structurally the members of this class differ but little from 

 the Schizomycetes, although they are of a much larger size. 

 The cells generally show a little more coherence than in the 

 last class. 



They live in fresh or stagnant water, or upon damp 

 ground, rocks, or decaying wood. Unlike the Schizomycetes, 

 they do not normally inhabit pulrid solutions. 



282.— Order Chrooeoceacese. This is made up of uni- 

 cellular plants. Tiie cells, which are spherical, oblong, cylin- 

 drical, or angular, are either single, or more commonly united 

 by a common jelly into families. Cell-division (in reality 

 internal cell-division) takes place in 

 either one, two, or three planes (Fig. 

 147). 



Four genera are known in the United 

 States, viz., (1) Chroococeus, with glohose, 

 oval, or angular (from pressure) cells, which 

 aj-e solitary or in free families; our three 

 species grow on wet rocks or in springs ; (3) 

 Olceocapsa (Fig. 147), with spherical cells, 

 which are solitary or in enclosed families ; 

 Fig. Wi.—maioeapsa indif- 0"r single species forms a firm grumous or 

 ferent stages of growth, show- gelatinous coating of a, light brown color 

 ing mode ot cell-mnltiplica- "^ , , ,„, „, , . 



tion. The daughter cells are on wet rocks ; (3) Clceosp/imnum, with very 



wanrmem'ofhlifcX"7 small cells, forming a thallus-like mass; we 

 youngest ; S, oldest stage, have one species, forming a, light-colored 

 X 300.— After Sachs. ggyjjj ^^ stagnant water ; (4) Merismopedia, 



with globose, oval, or oblong cells, which occur in tabular families of 

 four, eight, sixteen, etc. ; our two species inhabit streams and fresh 

 ponds. 



283.— Order Ifostocacese. The plants of this order are 



* Phycocyanine, the blue coloring-matter, is extracted from the 

 crushed plants by cold water ; the solution is blue by transmitted and 

 blood-red by reflected light. After the extraction of phycocyanine, 

 treatment of the crushed plants with stronjr alcohol produces a green 

 solution which contains chlorophyll, and a yellow coloring-matter, 

 phycoxanthine ; the latter may be separated by shaking up with the 

 green solution a large quantity of benzine, which takes up the chloro- 

 phyll, and when at rest rises and forms a green upper layer containing 

 chlorophyll, below which is the yellow alcoholic solution of phycoxan- 

 thine. 



