PLANTS AND ANIMALS 3 



Animals. Plants. 



4. Have no power of manu- Have power of manufacturing 



facturing food material, but complex organic corn- 



must apparently receive pounds or food material 



their sustenance from food from simple substances 



previously built up by the such as minerals, air, and 



plant. water, in the presence of 



sunlight, provided the plant 

 is green (i.e., possesses 

 chlorophyll). 



5. Inhale oxygen gas from the Have the power of absorbing 



air, and exhale carbon carbon dioxide gas and ex- 



dioxide gas from the lungs haling oxygen gas during 



chiefly (Respiration). sunlight, in addition to the 



process of respiration. 



The last two distinctions are highly important, 

 since they show us that the higher animals, at any 

 rate, are absolutely dependent on the existence of plants, 

 as the latter purify the air by absorbing large quantities 

 of carbon dioxide gas, and at the same time build up 

 food material for the Animal Kingdom. Without 

 plants, the air would tend to become foul, and the 

 Animal Kingdom either extinct, or its members would 

 have to find some other mode of existence. 



In civilised countries the provision of a sufficient 

 supply of plants cannot be entrusted to nature alto- 

 gether; hence it is necessary where animals are kept, 

 either as the servants of man or to supply him with 

 food, that he should co-operate with nature in the 

 growing of plants, so as to provide an adequate, if not 

 an abundant supply of plant-food for the requirements 

 of domesticated animals. 



It will therefore be convenient to describe more 

 in detail how the various food constituents are 

 manufactured by plants, before dealing with questions 

 of animal nutrition. 



