ELEMENTS OF AGRICULTURE 
m 
CHAPTER IL 
Stimulants . 
LESSON IX. 
ASHES. 
54. Ameliorators, as we have seen, do not exercise a 
direct influence on vegetation ; they are generally destined 
to modify the nature of the soil, by rendering it lighter or 
more compact (see Nos. 6 and 7). There are other sub¬ 
stances again which, without modifying in most cases the 
texture of the soil, exercise a direct influence on vegeta¬ 
tion, by exciting the organs of plants to draw a greater 
quantity of food than they otherwise would from the soil 
and the atmosphere. These substances are called stimu - 
lants. 
55. Sometimes a stimulant has also the property of 
modifying the texture of a soil; in this case it may be 
called a stimulating ameliorator. Some kinds of ashes 
come under this head; and it is for this reason that we 
treat of them immediately after the ameliorators, 
56. We give the name of ashes to the residuum left by 
the combustion of organic substances of vegetable or ani¬ 
mal origin. The efficacy of these ashes depends, in a great 
measure, on the elements of which they are composed. 
The principal kinds employed are wood, turf, and coal 
ashes. 
57. Wood ashes are the most valuable, and more gener° 
ally used. They ar6 formed of salts, of earths, and me tab 
