OTHEK METHODS OF OBTAINING FOOD 199 



the base of the stem there is found a cluster of fairly stout 

 roots 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 absorbing food. Their 

 roots 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, lying 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 on the roots at the points where 

 contact with the humus is effected. Many of these 

 saprophytes have the cells of their cortex infested with the 

 hyphae 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 con- 

 struction. 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 proteids, 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 



