SUPPLEMENT 



CHAPTER VI. 



FERNS AND THEIR RELATIVES. 



The plants of this chapter constitute the group Archegoniatae, a 

 name suggested by their method of reproduction ; but while their 

 peculiarities of reproduction are of special interest to the biologist, 

 and form properly a basis for classification, the subject is not within 

 the comprehension of children, and so is hardly touched upon in the 

 Reader. A thorough study of the reproduction of ferns and all higher 

 plants demands skillful work with the microscope, but perhaps all 

 teachers should have some general idea of the subject. 



This division of the plant world, Archegoniatae, is the highest 

 among flowerless plants, or, more properly, among plants that do not 

 produce seeds. It includes two groups, the Bryophytes, comprising 

 mosses and liverworts, and Pteridophytes, that is, ferns, horsetails, 

 club-mosses, and a few others. All members of these groups bear 

 organs called antheridia, which contain fertilizing cells called sperm 

 cells, or spermatazoids ; also organs called archegonia, which contain 

 egg cells or oospheres. As in seedless plants generally, the fertilizing 

 cell swims to the egg cell ; it is only in seed-bearing plants that the 

 fertilizing cell, the pollen grain, is transmitted through the air. 

 Necessarily, then, all Archegoniatae must inhabit moist places. After 

 the union of sperm and egg cells, there grows a more or less complex 

 body that produces spores. From these spores grow the plant bodies 

 that bear archegonia and antheridia, and so on ; so there are always 

 two phases two generations in the old terminology in the life of 

 these plants : from the spores grow the sexual plants ; from the union 

 of two cells produced by these plants grows the spore-bearing plant, 

 or sporophyte, as it is sometimes called. 



The plants that grow immediately from liverwort spores are usually 

 similar to Nos. 9 and 10, Fig. 30, that is, they are horizontal leaf-like 

 bodies fastened to the soil by root-hairs. The antheridia and arche- 

 gonia are imbedded in these bodies ; sometimes both kinds of organs 



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