PRACTICAL INFERENCES. Ill 



In offering a few general considerations on these sub- 

 jects, in addition to the numerous incidental references 

 in other pages, it may here be convenient to arrange 

 plants according as they are cultivated for their roots, 

 inclusive of root-like organs, for their stems, and for 

 their leaves, fruits, or seeds ; omitting all those special 

 details . pertaining to what we may term the individual 

 constitution of plants. 



Plants Cnltivated for their Roots, etc, Under this 

 head are included such crops as turnips, kohl rabi, 

 potatoes, beet-root, mangels, and onions. In all of these 

 the cellular tissue largely preponderates over the fibrous. 

 The cells are filled With water and with various substances, 

 such as starch and other secretions. In the economy 

 of the plant these secretions are manufactured in one 

 season, stored in the cells, and used up in the next season 

 for the production of leaves, flowers, and seeds. The 

 work of the leaves then of these plants differs to some 

 extent according to season ; those of the first year work 

 to build up the plant and to store up the secretions in 

 the " roots" or tubers, while the office of those produced 

 in the succeeding year is more particularly to form and 

 nourish the flower, fruit, and seed, and to secure the ac- 

 cumulation of nutritive matter in the seed. Unless the 

 farmer requires the plants to seed, he uses up the roots 

 for his own purposes before any demand is made upon 

 the plant for flower and fruit building. 



Speaking generally, the indications furnished by the 

 nature of the plants, point to the necessity or desirability 

 of a light, rich, friable soil for their culture, one which 

 will permit of ready root range, and which, while sup- 

 plying ample food, shall not harbor stagnant water. 

 Rapid growth and vigorous leaf-action are also indicated, 

 as, when these are secured, the cellular portions required 

 grow in proportion faster and more freely than the 



