420 



BRYOPHYTES (MOSS PLANTS) 



plants of some Mosses can be identified by a small terminal cup 

 in which the antheridia are produced. 



The antheridia produce numerous swimming sperms, and, when 

 there is suitable moisture, the sperms reach the archegonia, swim 

 down the long necks into the venters, and fertilize the eggs. 

 The fertilized egg begins to grow almost immediately after fer- 

 tilization, and like the fertilized egg of the Liverworts, it develops 

 in the place in which it was formed. By rapid growth and cell 

 division, it soon forms a spindle-shaped body with one end called 

 foot pushing into the stem of the gametophyte to absorb food, 



FIG. 375. A protonema of Moss (X 50). Buds which develop leafy 

 gametophores are shown at b. . 



and the other end pushing into the air, forming a stalk called seta 

 which bears a sporangium at its upper end in which the spores 

 are produced. As the sporophyte develops, the venter about the 

 young sporophyte and also the neck of the archegonium enlarge. 

 Finally the venter is ruptured and the enlarged archegonium is 

 carried up by the sporophyte, forming a pointed cap on the top 

 of the sporangium. When the spores are shed and fall on a 

 moist soil, they produce new gametophytes. However, the 

 spore does not grow a leafy plant directly, but first produces 

 an Alga-like filament which branches and creeps over the 

 substratum (Fig. 375). From bud-like structures on this fila- 

 ment, the leafy green plants grow, thus completing the life 



