FOOD OF PLANTS, AND HOW THEY TAKE IT. 
107 
into its structure, is the action of that body directed, the 
nerves, vessels, &c., remaining, in the mean time, perfectly 
sound. 
44 There is, besides, no room whatever for astonishment, in 
the extraordinary energy which poisons display, when ad¬ 
ministered to the higher animals, while the lower classes 
remain infinitely less sensible to their action. A bird is 
struck dead, as if by lightning, by a dose of digitaline, which 
slowly destroys a mammiferous animal of an equal size, and 
is not sufficiently strong to kill a reptile. The fact is averred 
with regard to other toxic substances, as you are perfectly 
aware : histological elements are submitted, in fact, to the 
influence of external agents, in direct proportion to their 
vital energy. 
44 But not only do the tissues of various animals differ with 
respect to the degree of sensibility which they exhibit under 
the action of foreign bodies; the proposition is equally true, 
when applied to homologous tissues in the very same animal. 
Thus digitaline, long before it acts upon the contractile powers 
of other muscles, arrests the motions of the heart; a result 
which may, no doubt, be attributed to the ceaseless activity 
of the cardiac fibres : being, therefore, of all muscles the most 
energetic in the performance of their functions, they are 
naturally found to be, at the same time, those which expe¬ 
rience, long before the rest, the noxious influence of poisons. 
We are aware, besides, that a striking inequality is observed 
in the results obtained by simulating various systems of 
muscles through different means ; and that muscular fibres 
which act in obedience to the will are infinitely more sen¬ 
sible to the galvanic stimulus than those which it is not in 
our power to contract at will. 
“You therefore perceive, gentlemen, that the general 
effects obtained by the use of medicinal agents are to be ex¬ 
plained by the modifications which they produce in the pri¬ 
mitive elements of which our tissues are composed.” 
THE EOOD OF PLANTS, AND HOW THEY TAKE IT. 
By Dr. John A. Warder. 
A Taper read before the Tomological and Horticultural Society 
of Southern Illinois. 
(Continued from p. 51.) 
We are told that the northern provinces of Holland export 
a million pounds of nitrogen annually in their cheese; this 
must have been taken into the organisms of the cows, from 
