Classification of Plants 



229 



separate stems, are more difficult to find. They are not sur- 

 rounded by so conspicuous a rosette. 1 \ , 



The sperm- cells escape, and swim to the 

 egg- cells in much the same way as they do in 

 Marchantia. When the egg- cells have be- 

 come fertilized, they send up stalks, which 

 are tipped by little capsules. You can find 

 them in great numbers when the mosses are 

 fruiting. Some of the capsules will have 

 little hoods, the remains of the archegonia 

 which have been carried up. Remove one. 

 On the capsule is a small lid. Take it off 

 with a needle. Under the lid is a mouth 

 with a row of teeth. Breathe on them 

 several times. What happens ? They open 

 and close. When ripe the capsule is filled 

 with spores. They sift through the teeth 

 during the summer, and when rain comes, or 

 when they lodge in a moist place, they send 

 out thread-like plants very much like an 

 alga ; it is from these threads that the leafy 

 stems grow.^ 



Division III. — Pteridophyta. 



Here too there is a distinct alternation of 

 generations but in this division the spore- 

 bearing generation is the more conspicuous. 

 It acquires stem leaves and roots and be- 

 comes quite independent of the gameto- 

 phyte. The Pteridophyta include the ferns, 

 the club mosses, and the horse tail or Equi- 

 setum, which is found in Eastern districts. 



Fig. 203. — 1. Moss 

 plant. II. Swim- 

 ming sperm-cell 

 (magnified). 

 (From Thom^ and 

 Bennett's " Struc- 

 tural and Physio- 

 logical Botany ' '. ) 



^ The capsule with its stalk is the sporophyte. 

 At the base of the stalk, the foot draws nourishment 

 from the leafy part, the gametophyte. The two 

 generations, the one bearing the sexual cells and the other the spores, al- 

 ternate with one another and exhibit what is known as AHernation of 

 Generation in plants. 



