DIGESTION 243 



chapter. Digestion, though most generally associated in 

 plants with the utilisation of reserve materials, may 

 thus occasionally be met with in connection with the 

 absorption of food from without, when it is a process pre- 

 cisely similar to the digestive processes of the higher 

 animals, though it is somewhat simpler in the details of 

 its mechanism. 



The intra-cellular digestion of plants agrees very closely 

 with that of many of the humbler animals, and corresponds 

 also with such processes in the higher forms as the utilisa- 

 tion of the glycogen of the liver and the fat of various 

 regions. 



We have seen that in a few rare cases protein material 

 is absorbed into the plant-body through various leaves 

 or modified foliar organs. The insectivorous plants are 

 materially assisted in their growth by capturing and 

 digesting various insects, the products of the digestion 

 being absorbed by the surface of the leaf or other organ 

 concerned. We examined several of these mechanisms in 

 some detail in Chapter XIV. 



Absorption of food from without, after preliminary diges- 

 tion, is much more frequently observed when we study the 

 nutritive processes of the Fungi. Not only protein, but 

 also carbohydrate and fatty substances are thus digested 

 outside the body of the plant, and the products of the diges- 

 tion are subsequently absorbed. 



We have then to inquire how these processes of diges- 

 tion, whether internal or external, are brought about. 



The protoplasm of the cell, among its many properties, 

 no doubt has the power of setting up these decompositions, 

 and probably in many of the very lowly plants, in which 

 the whole organism consists of only a few protoplasts or 

 perhaps a single one, the work is altogether effected by 

 its instrumentality. The protoplast, in fact, carries out 

 all the various processes of life by the interactions of its 

 own living substance with the materials absorbed by it, 

 aided in the constructive processes by the chlorophyll 



