32 ON THE ASSIMILATING AND ELABORATING POWERS OF PLANTS. 
On the assimilating and elaborating Powers of Plants. 
—Every plant with which we are acquainted contains some predomi¬ 
nating specific principle., detectable to some one or other of our senses, 
and by which the individuals or whole tribes are known from each 
other. In speaking of the essential qualities of plants, they are desig¬ 
nated sanative, or poisonous, or insipid; or, in other terms, they are 
dietetic, or medicinal, or necessary in the arts. 
That these different vegetable qualities are elaborated by the internal 
structure or organisation of the plant, is sufficiently obvious; because 
the food of plants growing on the same spot must be very similar in 
quality, though it may differ in quantity. It has been supposed that 
every different plant selects its own peculiar food, This is pos¬ 
sible, but not at all probable ; because qualities and distinct chemical 
bodies are found in plants, which are found nowhere else. The most 
accurate chemical analysis of the soil in which plants are nourished, or 
of the water or air by which they are fed, never elicits the presence of 
the many qualities found in the plants themselves ; and, therefore, we 
can only rationally conclude that it is the structural powers, united 
with the vital action of the system, which assimilates the crude food 
into the essential qualities of the plant; for if this be not so, how 
is it that the Antiaris or Ipo toxicaria , the Upas-tree, elaborates a 
deadly poison, while the Saccharum offieincirum , the sugar-cane, grow¬ 
ing close beside it, elaborates one of the most wholesome juices? Is 
either the poison or the sugar in the soil, or air, or water? We 
imagine not. 
The essential qualities of every plant are inherent, and continued 
from generation to generation ; but how the membraneous structure 
which contains the juices, and under the action of solar light, and 
heat, and air, changes them from a crude to a perfect state, is one of 
those natural phenomena which will probably ever remain inexplicable. 
It is easy to surmise that pre-existing qualities may, by amalgamation, 
assimilate the newly inducted sap with the properties or* peculiar 
qualities of the old. On a very different subject, it has been said 
that “ a little leaven leaveneth the whole lump; ” and the assimi¬ 
lation of the new with the old sap may take place perhaps in the 
same way. 
When the elaborating power of living vegetable membrane is con¬ 
sidered, we cannot avoid comparing it with the apparatus of the 
chemist. It is composed of innumerable cells, and tubes, and vessels, 
into and through which the juices enter and percolate, at a greater or 
less distance from the sun’s light and heat, and, according to their 
