196 VEGETABLE PHYSIOLOGY 



CHAPTEK XIV 



OTHER METHODS OF OBTAINING FOOD 



IN our introductory considerations of the true nature of 

 the food of plants, and of the manner in which they obtain 

 it, it was pointed out that there are stages in the life- 

 history of all plants during which it is imperative that they 

 shall be supplied with food in a form in which they can 

 assimilate it at once, constructive mechanisms either being 

 altogether absent from them or not having been developed 

 at the particular time under consideration. There is thus 

 in every plant a power of assimilating organic food so 

 supplied, a power which in some cases is permanently 

 relied upon, sometimes completely, sometimes only 

 partially, and which in other cases is laid aside as soon 

 as the chlorophyll apparatus becomes developed. The 

 need for the supply of the organic food is always felt by 

 every protoplast, and the latter cannot be nourished except 

 by it. We may contrast in this respect the individual 

 protoplast and the colony of which it is a member, the 

 latter being able through the co-operation of its individuals 

 to construct the organic food which must be provided for 

 the use of every member, even of those to which the work 

 of construction is allotted. 



The constructive power may be partially or wholly lost 

 or undeveloped ; in such cases the loss must be com- 

 pensated for by the supply from outside of the material the 

 plant is not able to synthesise for itself. 



Examples of plants possessing different powers of such 

 absorption are supplied by every class of the vegetable 

 kingdom. They are most conspicuous among the Fungi, 



