1891.] on British Mosses. 241 



different. In the mosses, where the sporogone co-exists with and is 

 organically connected with what I have called the moss plant, it is 

 evident that the two generations are not such, according to the more 

 popular notion of that word; they are not independent, nor 

 necessarily successive. 



A comparison of the first and second columns of the last table 

 reveals at once the likeness and the unlikeness of the life-histories of 

 the moss and of the fern. In each case the spore produces a growth 

 of the form and nature entirely unlike the mother-plant — in one case 

 a hypha, in the other a thallus. But whilst in the moss the proto- 

 nema produces the moss plant, in the fern the prothallus itself is the 

 home of the male and female organs, and of the sexual process, so 

 that the fern plant belongs to the sporophytic and the moss plant to 

 the oophytic generation ; the fern plant is the result of the sexual 

 union, whilst the moss plant is produced from an asexual spore ; the 

 fern plant produces spores asexually, the moss plant produces the 

 sporogone as the result of the sexual union. 



The observations which arise in connection with this comparison are 

 numerous. (1) It is the belief of botanists, ever since the investigations 

 of Hofmeister, that not mosses and ferns only, but all the phanerogams, 

 go through an alternation of generations consisting of the oophytic 

 and sporophytic generations. (2) It appears that the mosses and 

 the Characeae are the only groups of plants in which the conspicuous 

 and vegetative organism — the plant, in ordinary parlance — belongs 

 to the oophytic generation : (3) That, in consequence, the plant of 

 the moss is in no sense the ancestor of the plant of the fern, or of the 

 phanerogams, but belongs to a different generation from these ; and 

 further, that the leaves, the stem, and the epidermis of the moss have 

 no genetic connection with the leaves, the stem, or the epiderms of 

 our flowering plants, whilst the fibro-vascular bundles of the sporo- 

 gone of the Polytrichum, and the stomata on the apophyses of some 

 mosses will belong to the same generation which, in the vascular 

 cryptogams and phanerogams, produces similar organs. (4) That the 

 great chasm in the systematic arrangement of the vegetable kingdom 

 between the mosses and the ferns is thus accounted for by their 

 belonging to different generations, so that the ferns are not in any 

 sense descendants of the mosses, but only collateral relatives, as thus — 



Fcms. 



Mosses. 



Algee. 



