THE BEGINNINGS OF PLANT LIFE 7 



living substance of the cell or plant. As these 

 plant cells all show more or less clearly a line of 

 division in the middle, they might seem to be 

 two separate cells joined together ; but such is 

 not the case, each desmid being but one cell. 

 When reproduction is about to take place, the 



Fig. 3. Other forms of desmids, chiefly Micras- 

 terias denticulata. Actual length about T ^ of an 

 inch 



contents of the cell divide into the two halves^ 

 which seem to draw away from each other, 

 and so become constricted towards the centre, 

 and finally break away. Each irregular half then 

 soon develops the symmetrical crescent shape. 

 The above example (Fig. 3) is taken from 



