ANIMAL PATHOLOGY. 
a:38 
taken from the rabid animal almost immediately before. I 
have hinted at this already. It should be borne in mind with 
regard to many of the experiments that are made with the 
rabid virus. While the communication of the disease will be 
proof-positive of the condition of the animal from w^hich the virus 
was taken, the failure of that communication must never be con¬ 
sidered as a proof that the animal was not rabid. The fact seems 
to be undeniable, that the power of the virus rapidly diminishes 
when taken from the rabid animal, and that at no great distance 
of time it ceases altogether. The ascertainment of that time 
would be a very desirable matter; and especially would it be im¬ 
portant to us, who, in our post-mortem examinations of dogs that 
had died under suspicious circumstances, are exposed to very 
much real or imaginary danger. At all events I have hitherto 
escaped, although in many dissections the saliva must have come 
into abundant contact with my hands, and they were not always 
sound. I used, if I could, to let four-and-twenty hours, at least, 
pass before I commenced the examination. 
Different Persons and Animals are differently predisposed to 
become rabid. —Several breeds of dogs are covered with thick 
hair, and with a tough and thick hide which is not easily pene¬ 
trated, yet three-fourths of the dogs that are inoculated with the 
rabid poison are lost. Of the sheep and the human being a 
great many more escape. There is a predisposition to be affected 
in the former which does not exist in other animals. There is 
an affinity between the virus and the tissue with which it comes 
into contact, or there is a facility for the growth and develop¬ 
ment of it. This may depend on natural idiosyncrasy; or on some 
peculiar state of the constitution at the time; or there may be 
that about the diseased animal which may render the poison ex¬ 
ceedingly virulent at one time, and comparatively innocuous at 
another. 
The Vims resides in the Saliva. —A poisonous fluid mingles 
with this secretion, or the saliva itself is altered in its properties. 
It is deposited, as I have said, on some tissue or fibril, and there 
it lies for an uncertain period dormant, or, at least, not appear¬ 
ing to exert any deleterious agency. 
The Time of its Incubation in the Human Being. —There are 
strange and contradictory stories of this in the human being. 
Some have asserted that it has appeared on the very day in which 
the bite was inflicted, or within two or three days of that time. 
There would be no difficulty in deciding in what class of nervous 
diseases affections like these should rank. Dr. Bardsley relates 
a case in which twelve years elapsed between the bite and the 
disease. 11 the virus may lurk so long as this in the constitii- 
