DIGESTION 249 
protein food, as has been already shown in a preceding 
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 precisely 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 insectrvorous plants are 
materially assisted in their growth by capturing and digest- 
ing 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 
