50 THE PLANT IS A FACTORY. 



The Plant is a Factory. — •• All the labour 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 

 till 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 

 Tery life blood. " (^/as/ers, quoted from Gardener's Chronicle). 



A living plant is a machine or a factory, which, under the in- 

 fluence 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 recuper- 

 ate 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 constructing other parts of the plant, while 

 other portions of assimilated material take the form of starch, 

 oil, inulin, and are likely to be again changed and transferred 

 once or more times to other portions of the plant. 



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

 to b« used for plant food. Some soils may contain a large 



