252 
STRUCTURE AND LIFE HISTORIES 
OUTLINE OF LIFE HISTORY OF ULOTHRIX 
Plant Body 
(Undifferentiated into gametophyte and sporophyte stages) 
Physiological 
Sporangium 
4, 4, 
Zoos pore 
4, 4, 
Plant Body 
(Undifferentiated into 
gametophyte and sporo- 
phyte stages) 
4; 4 
Physiological 
Gametangium 
4- 4- 1 Eduction 
Isogamete Isogamete 
Conjugation 
Zygote 
4, 4, 
Swarm-spores 
4, 4, 
Plant Body 
PLEUROCOCCUS 
242. Habitat. Everyone is familiar with the green 
layer found on the outer surface of the bark of trees, on 
FIG. 1 83 . Individual plants of green slime (Pleurococcus vulgaris) , show- 
ing the tendency of the cells to remain attached after cell-divisions, thus 
causing transitions from a one-celled to a multi-cellular plant. 
wooden fences, and the moist shaded surfaces of stone 
steps or rocks. Careful observation will show that this 
crool is largely due to the presence of countless numbers 
