404 
GENERATION" OF POISONS. 
guard it from contagious diseases, we must increase them bv 
all possible means. 
These septic bodies, or specific poisons, are almost inva¬ 
riably organic substances, and are produced within the 
organism. It would appear that in several cases the noxious 
substance prevails throughout the economy; in other cases 
we only discover it in certain fluids. The virus which pro¬ 
duces hydrophobia belongs to this class; it resides exclu¬ 
sively in the animal’s saliva. We are not yet aware whether 
any one of the salivary glands is its peculiar seat, or whether 
it is indifferently secreted by all of them. No experiments 
have been tried on this point; but it has been experimentally 
proved that the venomous principle does not exist in the 
blood, since transfusion does not convey the disease from a 
mad dog to a healthy one. 
M. Claude Bernard goes on to observe, “it is a singular 
fact, and one which pre-eminently deserves our attention, 
that in so general a disease, the virus, which is alone capable 
of transmitting the affection, should be exclusively localised 
within one single apparatus, without existing in the blood at 
large. Yet, if we reflect upon the question, we discover, in 
the physiological state, a great many similar dispositions; 
the principles which concur in a vast number of physiological 
functions; pepsine, ptyaline, and the active principle of the 
pancreatic juice, are they not created by special glands? and 
is not the venom of serpents, which does not exist w’ithin 
the blood, produced by a special apparatus? Viewed in this 
light a mad dog resembles a viper or a rattlesnake. 
But, on the other hand, there exist several virulent dis¬ 
eases, in which the blood really appears to contain the mor¬ 
bid principle. This is the case with the glanders; and it is 
a well-known fact that healthy animals may be infected with 
the blood of a diseased horse, as well as with the slimy 
matter that escapes from the nose and mouth. 
But another particular, which will, perhaps, excite astonish¬ 
ment, is that the normal secretions, bile, saliva, gastric juice, 
and so forth, do not appear to contain the slightest vestige 
of this poison; wdiile, on the other hand, the pathological 
fluids appear to be impregnated with it, and possess the pro¬ 
perty of transmitting the disease to sound animals—a fact 
experimentally proved with regard to pus, the fluid contained 
in a hydrocele, and various other morbid secretions. For 
this reason alone are the autopsies performed on animals that 
die of the glanders attended with so much danger; the virus 
pervades the whole system, and the slightest wound is suffi¬ 
cient to inoculate the complaint. 
