CHAP. II. 
ROOT. 
255 
of the Physical Society of Geneva, has given an account of 
his important experiments, of which the following is an 
abstract : — He found that Chondrilla muralis, and Cichorace- 
ous plants in general, secreted a matter analogous to opium; 
Leguminous plants, a substance similar to gum, with a little 
carbonate of lime ; Grasses, a minute quantity of matter con- 
sisting of alcaline and earthy muriates and carbonates, with 
very little gum ; Papaveraceous plants, a matter analogous to 
opium ; and Euphorbias, a whitish yellow gum, and resinous 
matter of an acrid taste. 
He also found that plants actually possess the power of 
freeing themselves from matter that is deleterious to them, 
by means of their roots. Acetate of lead is a well-known active 
vegetable poison • he took two bottles, one of which. A, was 
filled with pure water, and the other, B, with water holding 
acetate of lead in solution. He placed a plant of Mercurialis 
annua with half its roots plunged in A, and the other half 
in B. After a short time the water in the bottle A 
contained a notable proportion of acetate of lead, which must 
have been carried into the system by the roots in bottle B, 
and thrown off again by those in bottle A. He also states 
that various plants which had lain several days in water 
charged with lime, or acetate of lead, or nitrate of silver, or 
common salt, in small quantity, having been carefully washed 
and placed in pure water, gave back from their roots the 
deleterious matter they had absorbed. 
It is difficult to speculate upon the results to which this cu- 
rious discovery may lead. It is in all probability an explanation 
of the necesssity of the rotation of crops, of the action 
of what are called weeds, of the utility of changing the earth 
of plants growing in pots, and of other phenomena which could 
not previously be accounted for. It requires, however, a 
great deal of ulterior examination ; but as the enquiry has 
been taken up by Dr. Daubeny, the learned Professor of 
Botany and Chemistry at Oxford, at the instance of the 
British Association, it is not to be doubted that a few years 
will throw much additional light upon the subject. 
