THE STORY OP OUR POODS 13 



CHAPTER II 



THE STORY OF OUR FOODS 



THE DEMAND FOR FOOD. To nourish ourselves 

 is the first duty we perform on entering the world, 

 and it is the last we discharge on leaving it. All 

 through life exists the necessity for finding our 

 daily bread. Nor is this a feature peculiar to man 

 alone. The fungus growing on the wall, the lofty 

 tree, the animalcule in the pool, and the higher 

 animal, through their whole existence must be fed. 

 Indeed, if one were to try to discover the sharpest 

 line of demarcation which might be drawn between 

 the world of life and that of non-living matter, we 

 should find it in this perpetual demand for food on 

 the part of the animal and plant. Growth of a kind 

 is certainly represented in the world of non-living 

 matter. A stalactite or lime pillar depending from 

 the roof of a cave will grow, but it enlarges its size 

 simply by additions to its outside surface, and 

 stoppage of this process of accretion, as it is called, 

 has little or no effect on the stability of the object. 

 The case is very different with a living being. Not 

 merely is a constant supply of food demanded, but 

 the material taken as nutriment is received into the 

 interior of the organism, and has to undergo a 

 process of digestion whereby it is assimilated and 

 ultimately changed into the substance of the living 

 being itself. In this latter respect we again perceive 

 a very striking difference between living things and 



