ABSORPTION IN THE CRYPTOGAMIA. 79 



than it retains, appears to be this; the solid mineral matters, 

 which constitute an important part of the food of the plant, are 

 contained in the water which reaches its roots, in excessively 

 minute proportion ; and it is therefore necessary, in order that a 

 sufficient amount of these may be obtained, that all the water in 

 which they are dissolved should be introduced. As this is by 

 far too much for the other wants of the plant, a large part of it 

 is got rid of by Exhalation. 



102. It is only in the more perfect plants, however, that we 

 find a restriction of this power of absorption, to one particular 

 portion of the structure. In the Sea- weeds, for example, the 

 whole surface appears equally endowed with this faculty ; and 

 there is, therefore, no occasion for that transmission of fluid from 

 one part to another, which is characteristic of those, in which we 

 find a stem (or something .correspondent with it), bearing roots 

 at one end, and leaves at the other. Accordingly, that which is 

 the natural condition of the latter, is fatal to the stemless plants ; 

 for if a Sea-weed be suspended partly out of the water, the upper 

 portion will die from drought, whilst that which remains im- 

 mersed will continue to live and grow, without transmitting any 

 of its moisture to the rest. (See . 41.) 



103. In some of the Cryptogam ia a little higher in the scale, 

 however, we find a condition much more approaching that of the 

 Flowering-Plants. Thus, in the Mushroom, we observe a soft 

 stem, which sends off fibres into the ground ; and these appear to 

 absorb by their whole surface, and to transmit the fluid they 

 have acquired, to the portion which is elevated in the air. In 

 the Mosses, the tissue of the stem is firmer, and the rootlets which 

 proceed from it are more woody ; these not only project from the 

 stem, but also from the under surface of the leaves; and thus the 

 dryness of the situations, in which these interesting little plants 

 find their subsistence, is in some degree compensated for. In 

 Ferns we have a woody stem and widely ramifying roots, like 

 those of the Phanerogamia. 



104. If we examine the roots of any common plant with a 

 branching woody stem, such as the Rose, we shall find that they 

 subdivide and spread beneath the ground, very much upon the 



