BRYOPHYTE DIVISION, MOSSWORTS 531 



plicated expedients were adopted by plants akin, and the outcome 

 is seen in such liverworts as Marchantia where small capsules are 

 made to hang from the branches of vertical thallus-lobes, or in 

 mosses like Sphagnum where a similar though erect capsule is borne 

 on an even more elaborately developed vertical branch of the nurse- 

 plant, which may live for many years. The most complicated ways 

 of securing elevation are found in the mosses typified by Funaria, 

 where both the nurse-plant and the spore-plant develop vertically 

 as far as they can — the latter, as it were, standing upon the shoulders 

 of the former — and by photosynthesis making food for the spores. 

 But the utmost height attained by these methods is only a few 

 inches; the foundation is weak. Growth which has to be accom- 

 plished during a short season of moisture or by improving brief 

 periods of wet weather, must naturally for the most part be limited 

 to rather soft tissue and small organs. IMosses often grow crowded 

 together like Sphagnum and thereby give mutual support and 

 store a supply of water for use in common; but although axes of 

 considerable height may be built in this way, the offspring is not 

 much benefited, for the crowded tops of the axes form virtually a 

 new surface above which is the only height effective for scattering 

 the spores. It is plain that effectiveness is not always favored by 

 complexity. 



The view suggested above that mossworts have evolved direct!}^ 

 from algte akin to Coleocha^te, although regarded as probable by 

 many botanists, receives no support from the study of fossil plants; 

 and is by no means the only view consistent with what is known of 

 the plants of to-day. Thus, it is ciuite possible that our mossworts 

 may be the more or less simplified descendants of larger plants 

 widely different from any we know, which themselves were de- 

 scended from seaweeds very unlike Colechsete and of which we have 

 now no trace. Not a few facts point to this conclusion ; but the truth 

 is we are much at a loss as to what to believe regarding the origin 

 of mossworts, and the question seems likely to remain long a puzzle. 

 Meanwhile, the hypothesis of direct algal origin may help us to 

 imagine something of the nature of the prol:)lems which had to be 

 faced by the earliest land-plants, whatever these plants may have 

 been; and may suggest, at least by analogy, something of the means 

 that may have proved most effective. 



When we remember that Bryophytes have had to depend almost 

 entirely upon superficial moisture it is not a little remarkable how 

 much they have been able to accomplish for the welfare of their 

 offspring. In spite of serious difficulties attending the use on land 

 of reproductive arrangements adapted to aquatic life, the.se little 

 plants very commonly achieve the benefits of cross-fertilization, 

 and of a considerable period of nursing for their young. All this is 

 made possible by the formation of archegonia which not only pro- 

 tect the protoplast of the egg, but by further development shield 

 the young spore-plant all through its time of special tenderness. 



