21 2 
The Keys of Death . 
[March, 
plied with such water in London. By this dilution-test it 
has been established that the poison of the cobra — and in 
all probability of other venomous serpents — is not a ferment, 
but a true chemical principle. Hence all anti-zymotics — 
such as benzoic, salicylic, carbolic, and cresylic acids — are 
necessarily impotent in the treatment of snake-bites. 
A distinction was formerly attempted to be drawn between 
poisons aCtive wben swallowed and others supposed to be 
potent only when introduced direCtly into the blood. To 
this latter class the venomous secretions of snakes were 
supposed to belong. This is now known to be an error. 
The poison of the cobra, if in a sufficient dose, is as deadly 
when swallowed, or applied to a mucous membrane, as if 
conveyed into the blood. Some of the disease ferments are 
certainly aCtive when swallowed, and, although there may 
be doubt concerning the poisons of rabies, of carbuncle, and 
of yellow fever, discretion is in all such cases the better part 
of valour. 
The common sense of mankind has always deemed poison 
to be specific, like food, but in an even more decided manner. 
It has concluded from observation that a substance, harmful 
or even deadly to certain animal species, may be to others 
perfectly innocent. Certain modern writers, undertaking 
somewhat prematurely to explain the respective nature of 
foods and of poisons, have more or less explicitly denied 
this view. In the very teeth of experience they have 
asserted that any given substance is poisonous or otherwise 
in virtue of its own chemical attributes, no regard being had 
to the nature of the animal into whose system it is to be 
introduced. This opinion is no less contrary to general 
analogy than to direCt observation. We bring together 
certain reagents in a glass vessel, and we obtain a given 
result ; but if we perform the same experiment within the 
stomach or in the tissues of an animal, the result will in 
many cases be seriously modified. Nor can we even from 
an experiment performed upon one species conclude with 
certainty what will happen in the case of another. Nay, 
even within the limits of one and the same species we en- 
counter in this respeCt more or less diversity. This is 
notably the case with the poisons of unwholesome mush- 
rooms, and of certain species of fish and mollusks. It is 
no uncommon thing for a number of persons to partake 
jointly of such esculents, and while some of the party sicken, 
even fatally, the remainder are not in the slightest degree 
inconvenienced. Such idiosyncracies cling even to the life- 
