THE LIVING WORLD 



205 



and scatters the spores when ripe. Each such spore is a 



double-walled cell containing protoplasm. If it falls on 



a suitable surface it gives forth a prolongation, the cells 



FIG. 35. 



an 



PROTHALLUS AND ITS PARTS MAGNIFIED. 



A Whole prothallus. 



s Spore. 



r Boot filaments or rhizoids. 



an Antheridia. 



ar Archegonia. 



B An archegonium greatly mag- 

 nified. 



cc. Canal cells. 



ce.c. Central cells. 

 C Two antheridia greatly mag- 

 nified. 

 an Antherozoids escaping from 



one of them. 



D Antherozoids still more mag- 

 nified. 



formed from which divide and subdivide till they form a 

 small cake-like expansion termed a protliallus, which 

 sends down root-fibres from its under surface. 



Then there appear on the prothallus a few rounded 



