In the stomachs of dogs which died rabid Dr. Gillman constantly observed traces of inflammation, and he tried to communicate the disease to rabbits by inoculating them with matter taken from pustules found in the stomach of a rabid dog, but no infection took place.

According to Professor Rossi, the nerves, "before they grow cold, participated with the saliva in the property of communicating rabies." He asserts that he once imparted the disease by inserting in a wound a bit of the sciatic nerve immediately after it had been taken from a living rabid cat.

Now, after all that has been stated concerning the hypothesis of the infectious principle of hydrophobia being more or less diffused through the solids and fluids of a rabid animal, and not being restricted to the saliva, perhaps the safest conclusion is not to reject the opinion altogether, but to consider it as at present requiring further proof.

Although many cases are to be met with in the records of medicine and surgery tending to convey the idea that the mere application of the saliva of a rabid animal to the sound entire skin of the human subject may give rise to hydrophobia, the assertion is contrary to general experience, and liable to a reflection which must overturn the hypothesis, namely, the slightest prick, scratch, abrasion, or broken pimple on the surface of the body, such as would not be likely in many instances to excite notice, may render the application of the saliva to the part a positive inoculation.

Instances are also reported, the tenor of which is to prove that the hydrophobic virus may take effect through a sound mucous membrane. But that this does not happen in the human subject is tolerably well proved by the consideration that formerly a class of men made it their business to suck the wounds caused by the bites of rabid animals, yet none of them contracted hydrophobia from this bold employment. The example of the nurse who repeatedly kissed the child without the least ill effect while it was dying of rabies has been already noticed in these pages. And if hydrophobia were apparently to arise in any rare instance from the application of the slaver of a rabid animal to the inside of the lips, no positive inference could be drawn from the fact, unless the means were also possessed of ascertaining that there were no slight abrasions about the gums or within the mouth previously to such application. Therefore, for the hydrophobic virus to take effect, it is generally if not always necessary that the infectious saliva be either applied to an abraded wounded or ulcerated surface. In the case of a bite, the teeth are the envenomed weapons which at once cause the solution of continuity and deposit the infection in the part. But the mere abrasion of the skin and the application of the infectious saliva to the denuded cutis will often suffice for the future production of the disease. As the mode of communication, then, is a true inoculation, it follows that the danger must depend very much upon the quantity of infectious matter conveyed into or applied to the part, the effectual manner in which the saliva is lodged in the flesh, the extent and number of the wounds, and particularly the circumstance of the teeth of the rabid animals having passed through no clothes, by which the saliva might possibly be effectually prevented from entering the wound at all. Hence bites on the hands and face are well known to be of the most dangerous description, especially those on the face, the hands being sometimes protected with gloves.

From what has been observed, however, it is not to be concluded that the disease always follows, even when the animal which inflicts the bite is decidedly rabid, and some of its 6aliva is actually applied to the wounded or abraded parts. On the contrary, experience fully demonstrates that out of the great number of individuals often bit by the same mad dog, and to whom no effectual prophylactic measure is extended, only a greater or lesser number are afterwards attacked with hydrophobia. When this difference in the fate of the individuals cannot be explained by the intervention of their clothes, the thickness of the cuticle at the injured part, the small size and superficial nature of the bite, the ablution of the part, or some other mode, in which any actual inoculation may have been rendered, ineffectual, it can only be referred to some unknown peculiarities or differences in the constitution of the several individuals. The latter conjecture seems more probable when the fact is recollected that some animals are more susceptible of rabies than others, and some appear to resist the infection altogether.

Dogs, for example, are more susceptible to the infection than the human species. Four men and twelve dogs were bitten by the same mad dog, and every one of the dogs died of the disease, while all the four men escaped, though, strange to say, these men used no other means of prevention but such as we see every day fail. There is also another instance of twenty persons being bit by the same mad dog, of whom only one succumbed to the disease.

Dr. Heysham has defined hydrophobia to be an "aversion and horror at liquids, exciting a painful convulsion of the pharynx, and occurring at an indeterminate period after the canine virus has been received into the system."

Dr. Cullen places it in the class Neuroses and order Spasmi, and defines it as "a loathing and great dread of drinking any liquids, from their creating a painful convulsion of the pharynx, occasioned most commonly by the bite of a mad animal."

Others have suggested the following definition, as more complete: "Melancholy, dread of cold air, of anything shining, and particularly of water," often arising from the bite of a mad animal. However the latter definition is perhaps equally objectionable, because there is not invariably a dread of shining bodies. While some writers represent it as a nervous disorder, others, amongst whom is Boerhaave, consider it as one of an inflammatory nature. In many systems of surgery hydrophobia is treated off with poisoned wounds, of one species of which it is strictly the effect.