PROTHALLUS PLAINTS. 97 



part covered by eternal snow, on which no plant could 

 thrive — are enciiisted by the dry bodies of Lichens. 



Leaving now the Fungi, Lichens, and Algae, which are 

 comprised under the name of Thallus plants, we enter upon 

 the second sub-kingdom of the vegetable kingdom, that of 

 the Prothallus plants (Prothallophyta), which by some 

 botanists are called phyllogonic Cryptogamia (in contradis- 

 tinction to the Thallus plants, or thallogonic Cryptogamia). 

 This sub-kingdom comprises the two provinces of Mosses 

 and Ferns. 



Here we meet with (except in a few of the lowest 

 forms) the separation of the vegetable body into two 

 different fundamental organs, axial-organs (stem and root) 

 and leaves (or lateral organs). In this the Prothallus plants 

 resemble the Flowering plants, and hence the two groups 

 have recently often been classed together as stemmed plants, 

 or Cormophytes. 



But, on the other hand, Mosses and Ferns resemble the 

 Thallus plants, in the absence of the development of 

 flowers and seeds, and even Linnaeus classed them with 

 these, as Cryptogamia, in contradistinction to the plants 

 forming seeds ; that is, flowering plants (Anthophyta or 

 Phanerogamia). 



Under the name of " Prothallus plants " we combine the 

 closely-related Mosses and Ferns, because both exliibit a 

 peculiar and characteristic " alternation of generation" in the 

 course of their individual development. For every species 

 exhibits two difierent generations, of which the one is 

 usually called the Proihalliiim, or Fore-growth, the other is 

 spoken of as the Cormus, or actual Stem of the moss or fern. 



The first and original generation, the Fore-growth, or Pro- 



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