Again, the bite of a naturally ferocious beast has often been thought to be attended with more risk than that of an animal naturally tame; and hence the bite of a wolf is said to be more frequently followed by rabies than that of the dog. This proposition is admitted to be true, but the explanation is erroneous. The true reason of the difference is, that a wolf usually seizes the face and inflicts a deeper bite, while a dog only snaps as he runs along, and mostly bites through the clothes. Then, again, the bite of a rabid animal may be rendered much more dangerous by being situated near a part or an organ which increases the difficulty or risk of adopting an effectual mode of removing the whole of the flesh in which the virus may be lodged. For example, bites near the large arteries, the eyes, the joints, etc, are of a more serious description than others. In fact, Dr. Hunter rated the hazard in some degree by the vascularity of the bitten parts.

The prognosis will always be more unfavourable when no proper measures have been applied to the bite soon after its infliction, and perhaps the risk may be increased by certain causes not having been duly avoided, which, as already stated, are thought to have a tendency to accelerate the attack of rabies. The exact time after a bite when the prevention of rabies is no longer practicable is quite an undetermined point, but every fact known upon the subject evinces in an urgent manner the stern necessity of adopting preservative measures without the least possible delay.

In almost all the dissections of patients who have died of rabies, certain indications of inflammation have been perceptible, more frequently in some part of the space between the pharynx and the cardiac opening of the stomach (or, in other words, the gullet), in the stomach itself, in the lungs, and membranes of the brain.

Dr. Trolliet opened with the greatest care six bodies of persons destroyed by this disease. "The mouth and fauces in each subject were first examined, and found of a pale greyish colour, scarcely lubricated with mucus, and quite free from all frothy matter. All the salivary glands seemed perfectly healthy. When the larynx, trachea, and bronchi were opened, they appeared to have been the seat of inflammation, the traces of which were most marked low down; here the mucous membrane was of the colour of wine-lees. In four of the bodies frothy mucus was perceived in the bronchi, larynx, and trachea." By this he infers "that the frothy matter seen about the mouth and lips of patients affected with rabies is secreted by the inflamed mucous membrane of the bronchi, and that it is this secretion, and not the real saliva, which contains the hydrophobic poison."

Ill giving an account of a dissection, another authority also remarked "that the frothy matter was only met with in the air-passages; that the salivary organs were unaffected, and that the saliva itself did not contribute to the formation of the thick slaver, which appeared to have issued from the chest."

From the preceding observations it would then appear-

First, that the mouth, strictly so called, and the salivary glands are without any alteration.

Secondly, that the mucous membrane of the air-passages is affected with inflammation, which in its highest degree extends from the division of the bronchi to the pharynx. When the inflammation is of less extent the pharynx appears sound, and when yet more limited it is usually not to be traced in the larynx, a neighbouring organ. The point where it seems to commence and is most strongly marked is at the lower part of the windpipe or in the bronchial tubes. Lastly, when none of these parts are found inflamed, the lungs themselves present vestiges of inflammation.

Now with respect to Trolliet's theory, wherein the hydrophobic poison is said to be contained in the mucous secretion voided from the lungs, and to be the product of inflammation of the membrane of the bronchi, and not derived from the salivary glands, the question requires the confirmation of experiment; for although the salivary glands are not the seat of pain, swelling, etc, it by no means follows that their secreting process may not have been subject to some peculiar modification on which the production of the hydrophobic virus depended. Thus severe and obstinate ptyalisms often occur, and yet there is no manifest change in the state of the salivary glands. According to Swieten and Mead, "there are sometimes no morbid appearances either in the head, fauces, chest, or stomach."

The dissections of two rabid sheep have been lately given, and it is particularly noticed that in these animals the lungs were sound, a fact that is very repugnant to the hypothesis adopted by Trolliet.

In three cases out of six the lungs were found emphysematous, that is to say, their interlobular substance was distended with air, and the pleura covering the lungs raised into a great number of transparent vesicles on the surface of these organs. In a fourth instance the emphysema was not observed in the lungs themselves, but in the cellular substance between the two layers of the mediastinum and under the muscles of the neck.

Morgagni also noticed vesicles of air on the surface of the lungs of a person that died of hydrophobia; while Trolliet presumes that this emphysema is occasioned by the rupture of one of the air-cells in the convulsive efforts of respiration, as sometimes happens when a foreign body is lodged in the throat.

In all the six subjects dissected by Trolliet they were observed to be gorged with blood. Now with respect to the state of the organs of the circulation as described by this authority, in three cases a good deal of air escaped from the heart and aorta. Morgagni is supposed to be the only other writer who has noticed a similar occurrence, and who also in another case saw air escape from beneath one of the coverings of the brain.

In two of Trolliet's cases some gelatinous clots were found in the heart and large vessels, but the groat mass of blood was black, and very fluid in the heart, arteries, and veins, as in subjects who have died of asphyxia. In all the six cases traces of inflammation were noticed in the brain or its membranes. The sinuses were filled with dark fluid blood, and one of the coverings (the pia mater) was much injected, and of a brownish hue. The same appearances were found upon the brain matter, and the vessels at the termination of the spinal cord were considerably enlarged. The surface of the brain was also studded with scarlet spots, which appeared to arise from blood effused from the small vessels of the pia mater into its cellular substance. In two subjects blood was extravasated towards the base of the brain in larger quantities. The plexus choroides was gorged with blood of a brown colour. Besides these and other changes there was a thickening of the pia mater. The substance of the brain was softer than usual, but the fluid in the lateral ventricles was in small quantity, and in two cases had a bloody tinge. The late Dr. Marshall believed that in rabies the brain was the part principally affected. Dr. R. Reid believed than an alteration of the spinal marrow was essentially concerned in the disease.

In dogs Dr. Gillman found the pharynx and oesophagus in a state of inflammation. Dr. Ribes found the pharynx and soft palate slightly inflamed. It is also conjectured that in many of these instances the inflammation extended to the gullet from the windpipe and bronchi.

Inflammation of the mucous membrane of the stomach and small intestines has likewise been very generally noticed in dogs. However, according to Dr. Gillman, no vestige of inflammation or any other morbid appearances are discoverable on the examination of animals that have died of rabies. By some the gall-bladder was found empty, the mucous coat of the stomach and bowels inflamed, and these organs much contracted.

From recent investigations made the following are the morbid appearances noticed in the dissection of dogs, horses, cows, and sheep destroyed by rabies: -

Firstly, The lungs and brain universally gorged with blood.

Secondly, Greater or lesser marks of inflammation in the mucous membranes of the bronchi, trachea, larynx, throat, oesophagus, stomach, and frequently even in that of the bowels, vagina, uterus, and bladder. Yet in two dissections more recently no particular changes were discoverable in the pharynx and oesophagus.

Thirdly, The air-passages filled with frothy mucus..

Fourthly, A collection of serum in the ventricles of the brain, and sometimes even between the membranes covering the spinal marrow; and, Fifthly, An unusual redness of the investment of the pneumogastric nerves.