112 BOTANY. 
Crass I. Green Sues (Cyanophycee). 
229, These are single cells, or chains of cells, usually of 
a blue-green or brownish-green color, and generally inhab- 
iting the water. They very commonly form slimy masses 
or films on the water, or the moist surfaces where they 
grow. In their decay they emit a putrid odor, and when 
abundant, as they sometimes are in city water-supplies, are 
quite troublesome and offensive. 
230. The lower Green Slimes are single-celled, as in 
anil the mode in whith the davahter-oolls are curroumded and enclosed by. the 
elatinous walls of the mother-cells. 4, youngest; E, oldest stage. Magnified 
ed, filament of Nostoc; B, end of filament of Oscillaria. Magnified 
300 times. 
Chrodcoccus, Gleocapsa (Fig. 48), and other genera. Each 
cell divides into two, and these soon divide again, and so 
on. In Gleocapsa the cell-wall is much swollen into a 
jelly-like mass. 
231. In the Nostocs and their near relatives (Oscillaria) 
there is a little coherence of the cells ‘into chains or fila- 
ments. The cells form by fission, but after formation 
adhere somewhat to each other. The Nostocs (Fig. 49, A) 
occur in water or on moist ground as jelly-like masses of 
