316 A TEXTBOOK OF GENERAL BOTANY 
Reproduction. Flagellates are reproduced by the longitudinal 
division of the cell (Fig. 319), no sexual reproduction being 
known. In many species the cell may become rounded and in- 
closed in a thick cell wall, forming a resting spore (Fig. 318). 
The protoplast, on germination, divides to form a number of 
new individuals (Fig. 318). 
Euglena. ‘This is a very common and well-known genus of 
the Flagellata (Figs. 317, 319), which is frequently so abundant 

Fig.317. Huglena showing various forms assumed by a single cell. (x 675) 
in small puddles of standing water as to give the water a green- 
ish color. Euglena has a single flagellum which enables it to 
swim through the water, but it can also crawl by means of 
movements which change the shape of the cell. In its usual 
form it has bright-green chloroplastids, but when grown in the 
dark in nutrient solutions it loses its chlorophyll and lives in 
the same manner as do many unicellular animals (Fig. 818). 
It reproduces either by longitudinal fission (Fig. 319) or by the 
division of the protoplast of rounded cysts or spores (Fig. 318) 
to form new individuals. 
