50 



SOIL AN IMPORTANT FACTOR 



1. It respires. 



2. It transpires — ^moistm^e is given off, particularly from 

 the leaves. 



3. It takes in substances (raw materials) : (a) Carbon dioxide, 

 (h) water/ (c) salts (containing nitrogen and mineral elements). 



4. It converts the raw materials into foods: (a) Protein, (6) 

 carbohydrates, (c) fats. 



5. It grows. 



6. It stores foods. 



The Plant a Factory. — ^As soon as the seedling establishes itself 

 in the soil it shifts its dependence for food from that stored in the 

 seed by its parent plant to that of its own manufacture. Thus 



^/^fy\ 



ar 



Cork mt/? 



two /?o/e>s "Seed/mas fasfe/^ecf 



Fig 19 — A plant culture in a fruit jar. 



the plant grows into a real manufacturing establishment, most 

 wonderful and mysterious throughout. The plant cells correspond 

 to the departments — the leaf cells being the most important; the 

 content of the cells, chlorophyll,^ etc., represents the machinery; 

 the raw materials taken in are carbon dioxide, water and salts 

 (Fig. 19); the power is the energy of sunlight; and the products 

 are foods, of which there are three classes — protein, carbohydrates 

 and fats. The common carbohydrates aie sugars and starches. 



Conditions and Requirements Dtiring Vegetative Period. — In 

 order that the average farm plant might carry on all its activities 



1 Only a comparatively small amount of the water taken in by plants is 

 used in the manufacture of foods — most of it is transpired. 



2 Chlorophyll is the substance in plants that gives them their green color. 



