72 THE GENERAL MORPHOLOGY OF THE PLANT. 



these lower vegetables which have now been mentioned, of what- 

 ever form, imbibe their food through any or every part of their 

 surface, at least of the freshly-formed parts. Their roots, when 

 they have any, are usually intended to fix the plant to the rock or 

 soil, and not to draw nourishment from it. The strong roots of the 

 Oar-weed, DeviVs Apron (Laminaria), and some other large Sea- 

 weeds of our coast, are merely holdfasts, or cords expanding into a 

 disc-like surface at their extremity, which by their adhesion bind 

 these large marine vegetables so firmly to the rock that the force 

 of the waves can seldom carry them away. Mosses also take in 

 their nourishment through their whole expanded surface, princi- 

 pally therefore by their leaves: but the stems also shoot forth 

 from time to time delicate rootlets, 

 composed of slender cells or tubes, 

 which grow in a downward direction 

 and doubtless perform their part in 

 absorption. Although sometimes of 

 scarcely higher organization than the 

 root-hairs which grow from the under 

 side of a Liverwort (Fig. 86), yet they 

 distinctly introduce the root. A Moss, 

 therefore, as respects its vegetation, is 

 an ordinary herb in miniature : it pre- 

 sents an epitome of the three universal 

 ORGANS OF VEGETATION, namely, Root, 

 Stem, and Leaves ; although its roots are 

 of a secondary and subordinate charac- 

 ter. In the apparatus of reproduction 

 there is more complexity, but no essen- 

 tial change of plan. The spores of 

 Mosses are formed by division of the 

 contents of mother-cells into fours (31) ; 

 and are contained in Spore-cases (or 

 Sporangia) of peculiar structure, which 

 are accompanied with some apparatus 



too elaborate to be described here, and are commonly elevated, 

 before maturity, on a naked and slender stalk. The reproductive 



FIG. 87. An individual of a Moss (Physcomitrium pyriforme), enlarged to about 12 times 

 the natural size. 88. Tip of a leaf, cut across, much magnified, to show that it is made up 

 (except the midrib) of a single layer of cells. 



