84 A LIVERWORT. 



a mass of spores, but in higher plants it will be seen 

 to have developed into the structure we ordinarily regard 

 as the plant body. In Coleoch&te the oospore becomes 

 enclosed by a heavy wall of cells, and finally forms a 

 mass of asexual spores that form new Coleochcete 

 plants. 1 Even in it we have the same sort of alternation 

 between sexual and asexual spores that we have in Riccia, 

 while we also have similarities existing in the two plants 

 both as to the form of the plant body and the 

 organs producing asexual spores. The structure that 

 grows from the oospore is little more than an organ 

 for producing asexual spores, but it is destined in the 

 course of evolution to become more and more important 

 until it is the dominant phase in the plant's life-cycle. 



1 It must be borne in mind that in Coleockcete the protecting tissue 

 about the resting oospore did not come from the oospore, as is true in 

 Riccia. See Davis on "The Origin of the Sporophyte," in the Ameri- 

 can Naturalist, 37: 411. 



