PRACTICAL INFERENCES. 111 
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 Cultivated for their Roots, ete.—Under this 
head are included such crops as turnips, koh] 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 
