CHAPTER TV 



FEEDING 



THE FEEDING OF PLANTS AND ANIMALS— TYPES OF 

 FEEDING— PARASITES— DIATOMS— BACTERIA 



Feed me with the food that is needful for me. 



Proverbs xxx. 8. 



The Feeding of Plants and Animals 



/jLll living organisms must have food. Protoplasm is per- 

 petually wasting or burning away, and the loss must be made 

 good or the plant or animal also wastes away, starves and 

 in time dies. All sorts of substances must come from the 

 outside, enter the body and be dissolved and distributed to 

 the living cells. These substances contain the chemical ele- 

 ments which are found in protoplasm (C, H, O, N, S, P, CI, 

 K, Na, Mg, Ca, Fe). There is, however, no general, universal 

 food which is suitable for all organisms, and, in fact, the food 

 is almost as varied as are the organisms. The nature of the 

 food enables us to separate plants from animals and fungi 

 from green plants. Although apparently the protoplasm of 

 plants and animals is the same, their food is different. 

 Animals can and do consume solid food; plants in general 

 cannot, and they must have food in a liquid or gaseous state. 

 Animals cannot assimilate and use as food simple binary 

 chemical compounds, compounds built up of only two 

 elements. They can only extract their nitrogen from proteins 

 and their carbon from proteins or from carboliydrates or 

 from fats. That is to say, they must be supplied with the 

 ternary compounds, which contain at least three different 

 elements. Now these elaborate substances are only formed 

 by and found in other animals or plants. Plants, on the other 

 hand, can live on chemicals which contain but two different 

 elements, water (H2O), carbon dioxide (COg) and ammonia 

 (NH3). These chemicals exist in the air, in the water and in 



