THE BRYOPHYTA 145 



higher external organisation. In like manner, the fruit, 

 or asexual generation, is far more complex than in 

 the Hepaticae. Except in the one point of possessing 

 true stomata, its complexity, however, is on quite different 

 lines from that of the corresponding generation in the 

 higher plants. The Mosses, in fact, constitute a remark- 

 able and very isolated group, highly developed in their own 

 way, but with no near affinities to other Classes of plants 



The Bryophyta, as a whole, form a perfectly well- 

 defined sub-kingdom, characterised by the occurrence of 

 a well-marked alternation of distinct generations, of 

 which the sexual is the more highly developed, so far as 

 the vegetative organs are concerned. The sexual organs 

 both archegonia and antheridia are constituted on 

 the same general plan as those of the higher Cryptogams, 

 though differing in many details. The Vascular Crypto- 

 gams, together with the Bryophyta, are sometimes classed 

 in one sub-kingdom under the name of Archegoniatce, 

 founded on the general similarity of the female organs 

 all through these groups. The mode of development of 

 the spores, by division of a mother-cell into four, is also 

 common to Bryophyta, together with the higher Crypto- 

 gams, and indeed Phanerogams also, so far as the 

 microspores (pollen-grains) of the latter are concerned. 

 Although, therefore, the Bryophyta are at present uncon- 

 nected by any intermediate forms with the vascular 

 plants, yet they have many points in common with 

 them, and the general lines of homology between all the 

 classes hitherto considered are not difficult to trace. 



Now we have done with archegoniate plants. The 

 families which remain to be considered are essentially 

 different, both in the organisation of their reproductive 

 organs and in the whole course of their life-history. 

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