192 VEGETABLE PHYSIOLOGY 
a few rudimentary leaves. At the base of the stem there 
is found a cluster of fairly stout root-like structures which 
intertwine with each other to form a mass sometimes as 
large as a man’s fist. These are developed only in masses 
of humus, from which they absorb the products of decay. 
These plants differ thus from normal phanerogams by their 
method of absorbmg food. Their subterranean members 
are not provided with the system of short-lived root-hairs 
which are so characteristic of the ordinary roots. They are 
not in need of such close contact with continually fresh 
particles of soil as are the latter, lymg as they do embedded 
in a mass of humus. In some cases all their external cells 
absorb material from this; in others special absorptive cells 
are present, but these are not localised like the ordinary 
root-hairs, and they are not being continually renewed, but 
remain active for long periods. Frequently they are only 
found at the points where contact with the humus is effected. 
Many of these saprophytes have the cells of their cortex 
infested with the hyphe of a fungus. 
The food which is thus absorbed from the decaying organic 
matter is not necessarily in a fit condition for immediate 
assimilation by the protoplasts. It may, and frequently 
does, require alteration before being available for nutrition. 
The plants of the next group which we must consider 
differ from the saprophytes in an important particular. 
Like them they are provided with a chlorophyll apparatus, 
and are consequently capable of carrying on carbohydrate 
construction. Indeed they are generally more active in this 
respect than the members of the last group. As in the case 
of the greater number of the latter, it is chiefly their nitro- 
genous material that they obtain nearly or quite ready for 
assimilation. They appear to need this nitrogenous food 
in the form of proteins, and they obtain it by capturing 
and killing various animal organisms whose putrefying 
bodies yield them what they want. 
The Utricularias, which are members of this group, are 
plants which live floating in water (fig. 91); they have a 
