280 FARMERS' INSTITUTES. 



THE FUNCTION OF GKEEN LEAVES. 



Leaves not unfrequently absorb water in a liquid state as well as in the 

 form of vapor, yet the roots absorb .most of the water for plant growth. 

 That leaves sometimes absorb water is most easily tested by observing the 

 revival of cut flowers or plants when placed in a moist tin box. 



''The paramount function of the leaf is the absorption and assimilation of 

 carbon, as such does not exist in the atmosphere, unless, indeed, as an 

 impurity in air of towns, and a very prejudicial one to plants." (Masters.) 

 The carbon of plants comes from carbon dioxide, and is decomposed through 

 the agency of chlorophyll under the influence of light. 



THE PLANT IS A FACTORY. 



"All the labor of the plant by which, out of air, water, and a pinch of 

 divers salts scattered in the soil, it builds up leaf and stem and roots, and 

 puts together material for seed or bud or bulb, is wrought, and wrought only, 

 by the green cells, which give greenness to leaf and branch or stem. We 

 may say of the plant, that the green cells of the green leaves are the blood 

 thereof. As the food which an animal takes remains a mere burden until it 

 is transmuted into blood, so the material which the roots bring to the plant 

 is mere dead food until the cunning toil of a chlorophyll-holding cell has 

 passed into it the quickening sunbeam. Take away from a plant even so 

 much as a single green leaf, and you rob it of so much of its very life- 

 blood." Masters, quoted from Gardener's Chronicle, 



A living plant is a machine or a factory, which, under the influence of 

 light and heat transforms raw materials into organic matter, suitable for 

 enlarging the plant, or enabling it to grow. In nearly all cases, some portions 

 of a plant are dying while others are growing; and to some extent, one 

 part is independent of other portions. This enables a plant to change its 

 place of growth, to feed on its own stock of nourishment, or to recuperate 

 when injured. The formation and enlargement of new cells constitute 

 growth. To be ready for absorption by plants, matter must be in a liquid 

 or gaseous condition. To a great extent a plant takes what it likes best, or 

 is capable of controlling the quantity of any substance absorbed. 



Of the materials assimilated, a part goes at once to form cell walls, cork, 

 mucilage, etc., and can never be changed by the plant into matter for con- 

 structing other parts of the plant; while other jiortions of assimilated mate- 

 Tial take the form of starch, oil, inulin, and are likely to be again changed 

 and transferred one or more times to other portions of the plant. 



Only a very small part of the most fertile soil is in condition to be used 

 for plant food. Some soils may contain a large amount of materials which 

 the plants cannot take, or do not need. A fertile soil is capable of retaining 

 plant food, while sandy soils, owing to their excellent natural drainage, are 

 not fertile unless frequently supplied with manure. 



Two different kinds of plants growing in the same field will usually be 

 found to contain certain substances in different proportion. Some are essen- 

 tial, others are not; some in large quantity, others in small quantity, yet, 

 strange as it may seem, by the chemical composition of a plant, we cannot 

 always tell what manures will benefit it most. 



From the soil plants obtain, by means of their roots, all their ash constitu- 



