MOSSES 



409 



The sporophyte produces spores. The gametophyte 

 produces sperms. It is better for food making to be con- 

 nected with the spore-producing genera- 

 tion than with the sperm-producing 

 generation. Why? The answer to this 

 question is also an answer to the ques- 

 tion, "Of what advantage to plants is 

 the increase of the sporophyte and the 

 decrease of the gametophyte? " 



Spores and sperms must both move 

 away from where they are borne. Spores 



must be scattered to 



reproduce the plant, 



while sperms must 



move to reach the 



eggs. Spores move 



through the air. 



Sperms always move 



through fluid. Now 



in nutrition one of the 



principal things which 



a plant body needs is 



light. If this plant 



body is a spore-bearing 



body, the more it 



grows up into the light, 



the better are the 



chances of its spores 



to be carried away through the air; 



it can help its leaf work and its spore 



distribution at the same time. But if 



this plant body is a sperm-bearing body, 



Fig. 206. — Lengthwise 

 section through a young 

 capsule of a moss 

 sporogonium. Only the 

 cells which are shaded 

 produce spores. Note 

 how greatly the spore- 

 producing tissue is re- 

 duced as compared with 

 the sterile tissue. 



Fig. 205. — An arche- 

 gonium of moss. 

 Note the long neck 

 and the stalk below 

 the venter. 



