The special characteristic, and what is considered an important diagnostic sign, is the absolute horror or dread of water. This being, for the most part, a very striking symptom of the fatal indisposition which results from the bite of a mad dog, and some other animals affected in the same way, the disease itself has been termed hydrophobia.

The oldest writers, as we learn from Caelius Aurelianus, used to employ the terms acrophobia, or a dread of air, and pantephobia, or a fear of all things, since the impression of cold air sometimes excites terror, and the disorder is certainly marked by a singular degree of general timidity and distrust.

Others, again, christened it phobodipson, signifying thirst, because the patient is thirsty, yet, notwithstanding, fears to drink. Several modern authors, however, objecting to any appellation expressive only of one symptom, denominate the disease rabies, and rabies canina, or canine madness. The French call it la rage.

With respect to hydrophobia, or the dreadful indisposition produced by the bite of a dog or other animal affected with rabies, or by the application of some of the secretions of such animal to a part of the body, the first clear mention of it is generally considered to be that made by Aristotle; but he must have had very erroneous notions upon the subject, since he sets down man as incapable of receiving the distemper from the bite of a rabid dog. Now concerning the antiquity of hydrophobia, I may mention that Dr. Hecker thought that the fact was conclusively proved that the disease existed at least four hundred years before Christ; aye, even in the most remote periods. But with respect to a name for the disorder, as the patient docs not commonly betray any tendency to fury at the outset, while the dread of water is in reality a customary attendant on the complaint, the terms Ia rage and rabies appear, strictly speaking, even more exceptionable than the word hydrophobia.

At the same time, in order not to imbibe confused notions fur whatever name be thought most appropriate for the illness, when it arises in the human subject from the bite of a mad dog, or some other animal similarly affected, it is therefore necessary to understand wel1 (and this to a certain extent may tranquillize an individual possessing a nervous temperament) that hydrophobia, in the sense of a horror of water or other liquids, is an occasional symptom of many diseases, and neither exclusively confined to the indisposition caused by the bite of a Tabid dog or certain other animals, nor even constantly attendant upon it. And therefore, with the view of avoiding perplexity, all hydrophobic complaints may be arranged in two general divisions: -

1. The first comprising all cases not ascribnble to the bite of a rabid animal, or the application of some of its secretions to an injured part of the body.

2. The second comprehending the examples preceded by one of those occurrences.

The cases included in the first of these divisions are again subdivided into the symptomatic hydrophobia and the spontaneous or idiopathic hydrophobia.

By the symptomatic form we understand that there is an aversion or dread of liquids, presenting itself as an occasional symptom of various diseases, as certain inflammatory, febrile, and nervous disorders; for example, epilepsy, injuries to the brain, etc., or the operation of particular poisons, etc.; and, again, in many of the instances of symptomatic hydrophobia the aversion or dread of fluids occurs on the same day as the cause on which it depends, or a few days afterwards, and, for the most part, may be cured with the disease which has given rise to it, or even independently of it. But, on the contrary, the hydrophobia from the bite or infection of a rabid animal does not develop until a considerable time has elapsed after the occurrence of the cause, and, when once formed, has hitherto defied the best efforts made in order to effect a cure.

Whatever analogy, therefore, may be imagined to exist between symptomatic hydrophobia and rabies, they differ essentially in their causes, progress, degree of curability, and also in the treatment required.

Spontaneous or idiopathic hydrophobia denotes the questionable form of the complaint, sometimes supposed to be induced by violent mental commotion, anger, fright, etc, unpreceded by any other primary disease to which it can be referred as a symptom.

Numerous facts upon record leave no doubt whatever concerning the reality of symptomatic hydrophobia, but perhaps none of the cases adduced in proof of the possibility of a spontaneous idiopathic form of the disease in the human subject are sufficiently unequivocal to remove all suspicion either that the complaint had been preceded by another primary disease, or had been the result of en unobserved or forgotten occasion, on which the infection was received from handling a dog or cat never suspected at the time to be affected with rabies.

Animals of the dog kind, including the wolf and the fox, are most frequently the subjects of rabies; and certain writers have maintained, that although it may be received and propagated by other animals, yet it always originates in some of the canine race. However, it is asserted that the disease sometimes arises spontaneously in cats, that is to say, without their having been previously bitten by another rabid animal.

But the moderns do not incline to the belief that it ever has been known to commence in this manner in other animals, though such an assertion is made not only with respect to man, but horses, asses, camels, pigs, bullocks, bears, monkeys, and even poultry.

Now it is certainly very interesting to inquire what animals are capable of communicating rabies, and what animals of receiving it. So far as our knowledge extends yet, it appears that animals of the canine species, with perhaps those of the feline race, are the only ones in which this disorder ever arises spontaneously, and they are capable of transmitting it to animals of their own kind, to other quadrupeds, and to man; while experiments tend to prove also that birds, at least the common domesticated fowl, may have the fatal malady communicated to them.