THE TRANSFORMATION OF FOOD 39 



tributes bile an antiseptic, and an alkali which 

 saponifies fatty matters. The food, in its passage 

 through the alimentary canal, is thus materially 

 altered, and, in the course of its journey, is gradu- 

 ally absorbed in its altered form by minute vessels 

 which permeate the wall of the canal in all directions 

 and is carried by them directly or indirectly to all 

 protoplasmic cells of the body requiring nourishment. 

 The undigested remainder is, in due course, voided 

 as excreta worthless to the organism. 



Our next task must be to study, although more Nutrition 

 briefly, the problem of nutrition in the higher plant, ^J^ep 

 Like the animal, the plant is composed of proto- plant, 

 plasm and the products of its activity, and the food 

 of the plant protoplasm, as of the animal protoplasm, 

 must be organic in its nature. Moreover, much of 

 this food, if stored as a reserve in insoluble forms, 

 must be altered by enzymes and rendered soluble 

 and appropriately prepared for assimilation. 



At the very outset, however, we meet with a great 

 difference between the two types of organism. As 

 we have already hinted, the green plant itself manu- 

 factures its own organic food from inorganic materials, 

 while the animal, being unable to do so, has to 

 depend upon organic material made by the plant or 

 absorbed by another animal from the plant. In a 

 word, the plant makes what it wants, the animal 

 takes what it can get. Manifestly, the digestive 

 secretions and apparatus of the plant need not be 

 so complicated or elaborate as those of the animal, 

 for, being able to make what it requires, it has not 

 so much altering to do afterwards. Nevertheless, 

 the first formed compounds are not always in the 

 most appropriate state for assimilation, and further, 

 as we shall find later on, the plant has great powers 



