244 



APPLIED BIOLOGY 



a spore may form one or more moss plants. The protonema, 

 then, is a sort of creeping stem able to produce erect branches. 

 It is part of the moss plant. 



FIG. 73. Moss. A, B, plant with spore-case (&) which has a lid (c) ; z, root 

 hairs. C, enlarged view of spore-case. D, sperm-cell. E, spermary, 

 sperms escaping. F, ovary with embryo (o). G, protonema; b, bud 

 from which moss plant develops. H, spore (s) germinating to form a 

 protonema. (After Parker, Strasburger, and others.) 



233. Alternation of Generations of Moss. It is evident 

 that, as in the ferns, the moss has an alternation of genera- 

 tions. The moss plant is the stage or generation which bears 

 the sex-organs, while the sporogonium produces the asexual 



