126 



BOTANT. 



Order 1. CYSTIPHOR^. Thb Blub-grben Slimes. 



221. These are the lowest and simplest of plants; they 

 live as single cells in the water, or they may be aggregated 

 into slimy films on sticks and stones. There is but one 

 family, Chroococcacem, represented by minute species of 

 Chroococcus, Gloeocapsa (Fig. 60), and other genera. 

 Each cell divides into two, and these soon divide again, 

 and so on. In Gloeocapsa the cell-wall is much swollen 

 into a jelly-like mass. 



Order 2. NEMATOGENE.ffi. The Nostocs, etc. 



222. 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. 61, A) 

 occur in water or on moist ground as jelly-like masses of 

 filaments. Some are amber-colored, some brownish, some 

 bluish green. The species of Oscillaria (Fig. 61, B) are 



A 



m 



Fig. 60. Fig. 61. 



Fig. 60.— Cells of Gloeocapsa in different stages of growth, showing di- 

 vision and the mode in which the daughter-cells are surrounded and en- 

 closed by the gelatinous walls of the mother-cells. ^, youngest stage; 

 £, oldest stage. Magnified 300 times. 



Fio. 61.— i, filament of Nostoc ; B, end of filament of Oscillaria. Mag- 

 nified 300 times. 



mostly dark-green filaments collected into felt-like masses 

 floating on the surface of the water, or growing on wet 



