SYSTEMATIC BOTANY. 99 



life — advantageous to both organisms— is called symbiosis. In 

 most of the common species the spore-bearing disks or cups 

 (called apothecia), are readily seen. The spores in their origin 

 and structure resemble those of many of the Fungi. In fact 

 the Lichens may be regarded merely as a group of the Fungi. 



Collect, examine and figure representatives of the forms of Lichens men- 

 tioned in the text — taking care to get those that have apothecia, i. e. those 

 that have visihle fruit-cups. This can be done more satisfactorily immedi- 

 ately after prolonged rain. Remove them from their substratum and put 

 under moderate pressure till dry, when they can be enclosed in pockets as 

 in the case of Fungi, or glued directly to herbarium sheets. 



14. The Bryophytes (Mosses and Liverworts) constitute 

 the next higher division of the vegetable kingdom. In this 

 group there is a well-marked alternation of sexual and non- 

 sexual generations. The first, or that proceeding from the 

 spore, bears the reproductive organs called archeyonia and an- 

 theridia. It is the sexual generation (giame^opA^/^e). After fecun- 

 dation there grows a sporocarp or fruit (called sporangium), in 

 which spores arise non-sexually ; i. e. not the result of the fusion 

 of two cells. This may be called the non-sexual generation 

 (sporophyie). The archegonium is flask-shaped, in the bottom 

 of which is a naked mass of protoplasm, the germ-cell, which 

 is the essential part of the female organ. The antheridium is 

 generally club-shaped or subspherical, supported by a pedicel, 

 and filled with many sperm-cells, each of which contains a 

 single, spirally coiled spermatozoid. The neck of the arche- 

 gonium is open at the time for fecundation and into it pass the 

 free spermatozoids, which fuse with the protoplasm in the 

 germ-cell. Thereupon a thick wall or covering is formed. Cell- 

 division now takes place, and the result of this development is 

 the formation of a spore-case (sporangium), and a supporting 

 pedicel, or seta. The spore-case with its seta remains attached 

 to the plant that produced it, is nourished by it, yet has no or- 

 ganic connection. This, the second, is called the non-sexual 

 generation, \yithin the sporangium the spores are formed, 

 and contain, besides colorless protoplasm, starch and drops 

 of oil, also chlorophyll grains. When ripe, the spore-case, as 



