114 PLANT LIFE ON THE FARM. 
only generalities can here be alluded to. The cultivator 
must observe for himself whether the plants he wishes to 
grow are naturally shallow or deep-rooted ; whether the 
roots break up into a dense leash of fine fibres encom- 
passing and traversing in all directions the soil within a 
certain limited area; or whether, as in the case of 
lucerne, the ‘‘ root” consists of along, thick under- 
ground stem, capable of extending itself for many feet, 
and giving off, within a small extent, only a compara- 
tively small number of fibres. The different forms of 
roots previously alluded to may be looked on as adapta- 
tions to different conditions of the soil, especially in 
relation to water, and the choice of site and mode of 
tillage must be governed by circumstances. Leaf-de- 
velopment is thus consequent on root-growth ; but, in 
addition, an adequate supply of moisture and heat and 
full exposure to light are demanded. The adjustment 
of these agencies is rarely under the control of the far- 
mer to anything like the same extent that it is in the 
case of the gardener. The gradener can often contrive, 
for instance, by appropriate modifications of treatment, 
to keep his plants in a growing condition, and to prevent 
them from “bolting” into flower, whereas the agricul- 
turist is much more the slave of circumstances. Drouth 
and heat check dis crops before their growth is complete, 
and induce premature development of fibre, of flower, or 
of seed. Excessive moisture and superfiuity of rich food 
will cause the crops to become too rank in their growth, 
to develop immature succulent tissue, comparatively 
devoid of the nutritious secretions in which their value 
consists, and will check the development of flowers. 
The observant eye of the farmer soon detects the un- 
healthy state of the crops by the color of the leaves. If, 
from any cause, root-action is deficient, or sun-heat and 
sunlight are lacking, the chlorophyll is not formed in 
sufficient amount, or is imperfectly developed, and the 
