the stalk wis proJucad, and the soil aa 1 atni)sphire mist hive 

 made up the deficiency. 



The leaves of the growing plant absorb from the atmos- 

 phere a gas, known as carbonic acid gas ; the roots take up wa- 

 ter, in which potash, iron, sulphur, lime, phosphoric acid, and 

 magnesia, are dissolved, and the roots and leaves both take up 

 nitrogen in combination with other elements. Within the plant 

 these simple substances are combined in wonderful ways, form- 

 ing many compounds having unlike properties, for example, the 

 carbonic acid taken in through the leaves, and the water taken 

 up by the roots, furnish the elements from which starch, sugar, 

 oil, vegetable acids, mucilage, gum, etc., are produced. By the 

 addition of nitrogen and sulphur a class of compounds are pro- 

 duced which resemble the white of eggs. Wheat gluten is an 

 example of this class. One of the chief characteristics of plants 

 is this power of taking the elements contained in the soil and air, 

 and from a few, forming an almost endless variety of substinces 

 having the most diverse properties. Sugar and acids, starch and 

 oil,' strychnine and quinine, are a few of the many. This power 

 is not found in animals. Not a grain of starch was ever pro- 

 duced from the elements of carbonic acid and water, except by 

 plants ; animals are dependent upon plants for their food. 

 During the growth of plants they are constantly taking in car- 

 bonic acid, using a part of it in the production of starch, sugar, 

 etc., and giving ofif oxygen ; the result of this is to use up the 

 carbonic acid of the atmosphere and overcharge it with oxygen; 

 animals, however, produce just the opposite effect ; they take in 

 and use oxygen and give off carbonic acid. This is the one thing 

 that keeps nature's books balanced. 



A plant put under a tight jar would in time so far use up 

 the carbonic acid as to die from lack of food ; a mouse under an- 

 other jar would use up the oxygen and increase the carbonic 

 acid until suffocated; the two if put under the same jar would 

 keep the air right for both. The oxygen given off by the plant 

 would supply the mouse while the carbonic acid exhaled by the 

 mouse would furnish just the kind of food necessary for the plant. 



FOOD. 



This word has been used. What does it mean? Any sub- 

 stance that can support life, or help to support it, \9,food. 



6 



