STRUCTURE AND LIFE HISTORIES 



OUTLINE OF LIFE HISTORY OF ULOTHRIX 



Plant Body 

 (Undifferentiated into gametophyte and sporophyte stages) 



Physiological 

 Sporangium 



Zoospore 



4. i 



Plant Body 



(Undifferentiated into 

 gametophyte and sporo- 

 phyte stages) 



4- 4- 



Physiological 

 Gametangium 



^ J, } Reduction 



Isogamete Isogamete 



Conjugation 



Zygote 

 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. 183. 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 



