seems certain that the virus of Cholera, whatsoever its nature, may be spread in different ways. That the atmosphere, though not in any of its states the cause of the disease, forms one medium for diffusing it, and this over great distances, is clearly to be inferred from numerous facts in its history. From the same evidence, and particularly from the details of its introduction into new localities, and passage across seas, it is impossible not to admit that its transference is frequently effected by human means; and it may perhaps be affirmed, without involving the question in more doubtful phrases, that man, the peculiar recipient of this cause of disease, is also the principal agent in its diffusion. On a question of this nature, it is always well to select a few proofs unequivocal and complete, wherewithal to meet the many ambiguous or anomalous cases which are certain to occur: and it would be easy to state several such in the history of Cholera, scarcely admitting of other interpretation than that just given.

*

Allowing this, some of the apparent contradictions which have embarrassed the question as to contagion may be solved, by referring to the habitudes of that class of animal life which the hypothesis assumes; and particularly to the

* One, which I think includes every condition of perfect evidence, is the transportation of Cholera from the infected towns of Liverpool, Dublin, and Greenock, to Quebec; in vessels having emigrants on board, among whom the disease existed during the whole passage across the Atlantic. The details of this occurrence, including the place, time, and manner in which the Cholera first showed itself in Quebec, are such as to leave no point of ambiguity. The circumstances which attend the transmission of the disorder over land are not often so explicit in their conclusions.

The Treatise on Pestilential Cholera, by Dr. Copland, published in 1832, contains an excellent statement of the argument regarding contagion, as of all besides relating to the disease. In adopting the opinion of its infectious nature, he has ably and justly dwelt on the inadequacy of the experiments by inoculation, and certain other modes of exposure, to negative this opinion.

circumstances which favour the propagation, diffuse the ova, direct the flight, fix the resting-places, or modify the virus, of the swarms thus supposed. We can understand in this sense the respective relations of man and the atmosphere to the spread of the disease. The human body may be a means of concentrating the morbid cause; and conveying it, possibly in a state more prone to inflict the disorder, to distant and detached localities. The atmosphere, the medium in every case of communication from one body to another, may itself, independently of man, carry the miasma over wide distances; and by its changes in temperature, humidity, and electrical state, produce many of the modifications observed. And in the separate or concurrent agency of these causes of communication a plausible solution is found of some of the more singular anomalies of the disease.

That man should be so peculiarly the subject of Cholera is a difficulty which belongs to all hypotheses, but least perhaps to that of an animal origin. It is difficult to conceive any other physical cause thus far exclusive in its effects; while, in support of this view, we have various analogies in insect life, and in the habits of parasitic animals already noticed. Though man, however, is chiefly obnoxious to this virus, whatever it be, we have proof that he is not exclusively so; and it is worthy of note, that the most distinct evidence relates to its effects on birds; and to the rare appearance of certain species of birds in the localities where Cholera is prevailing at the time.* The cause assigned in the hypo

* This fact of the effect upon birds is fully confirmed in a late report of the Medical Faculty of Vienna, upon whom the inquiry as to the influence of Cholera upon other animals, was expressly enjoined. A similar fact has been noticed in the history of other pestilences of older date, and attributed vaguely to atmospheric changes affecting this class of animals. The report just named is the most complete document we possess on the subject, and contains many very curious facts.

thesis under review is at least as probable as any other in explanation of this curious fact.

The question, connected with the preceding, why the miasma of the Cholera should destroy some persons, and leave others in the close vicinity little if at all affected, applies equally to other disorders of contagious and epidemic kind, and presents similar difficulties to every hypothesis; yet greater perhaps to the notion of an inorganic agent, than to a supposition which includes all the conditions of animal life; and particularly that form of life which is so rapid and abundant in reproduction, undergoes such remarkable changes, and is submitted to instincts of which we have. so little cognisance. No view, as far as can be seen, better applies to the various degrees of the disorder; - from the slight and ill-defined uneasiness about the epigastrium and bowels, subsiding without further issue to the powerful and virulent disease, producing instant collapse, and destroying life within a few hours of the earliest seizure.

These considerations bring us more directly to the pathology of the disease, and the relation of the various alleged causes to its actual symptoms. The weak part of medical science lies here, where morbid agents from without come into contact with living actions in the body: and, fairly examining into this subject in all its relations, we shall find how little real knowledge has been gained from the earliest date of medical history to the present day. Singular though the symptoms of Cholera are, in their suddenness and fatality, they offer no difficulty which does not equally belong to other kindred diseases. We may even go a step further, and affirm that the notion of an animal virus, applied to absorbing surfaces, and engendering the disorder by entering into the circulation, is that which on the whole best accords with

Q Q

the character of the disease, and with the analogies most obvious to other morbid affections. We have many proofs of the power and virulence of different poisons of this class, and of the remarkable changes they produce on the nervous system and the blood. The action of the morbid cause in Cholera seems to have most kindred with these: the change which takes place with such rapidity in the properties of the blood being, as I think, the great feature in the disease; the basis probably of all the other symptoms. The extreme depression of animal heat throughout the body; the peculiar secretions so largely poured out from the inner surface of the intestines; - the suppression of the natural secretions; -the severe spasmodic actions; the various effects on the nervous system; — and the typhoid and other symptoms which occur in sequel to the acute stage of the disease; are all more readily and consistently explained, by looking to this altered state of the blood, as the effect first resulting from the influence of the morbid cause.* Some of these symptoms, indeed, scarcely show themselves where the Cholera exists in so virulent a form as to terminate life in a few hours; proving thereby that they are not essential to the character of the disorder, nor to its event.

It is conceivable indeed, and we have no direct proof to the contrary, that the original impulse of the virus of Cholera may be upon some part of the nervous system: but I consider the supposition much more probable which makes the influence on the blood the first in the series of changes: and

* I would apply the same remark to the diseased or disorganised state of the inner coat of the blood-vessels, observed in many of the dissections after death from Cholera, and particularly described by Dr. Mackintosh.

The recent experiments of Dr. Namias, of Venice, show that inocu lation with the blood from cholera patients under collapse will often destroy other animals, as rabbits, within a few days, and by changes which render their blood again destructive to others of the same species.

it is undoubtedly that which has most obvious and general relation to the other symptoms of the disease. If the magnitude of the effect here seems out of proportion to the cause, we have but to look to the certain influence of other morbid agents on the blood; - whether the imperceptible virus of many contagious diseases the minute quantity of certain other animal poisons producing death or the action of different salts in preventing the coagulation of this fluid. Inability to explain the rationale of such changes applies alike to every view of the subject; and cannot therefore be admitted as an exclusive objection to one alone.

-

As respects the prevention and treatment of Cholera, little need here be said. Neither the hypothesis of which we are treating, nor any other alleged cause, can be considered as hitherto affording even plausible suggestions to this effect. The requisitions in common to every view are, the discovery of means to prevent the access of the cause or a specific capable of obviating the virus when received or remedies adequate to sustaining the body under its influence ;-objects, it must be confessed, hitherto wholly unattained. The singular uniformity in the proportion of deaths, in every place of the occurrence of Cholera over the globe, not only affords proof that no valid means of cure have been discovered for the disease, when fully developed; but shows, moreover, how inert even the most drastic remedies become, when directed against this extraordinary poison. Methods of treatment the most opposite, yet equally insisted upon by their respective advocates, and many of them such that their use would be dangerous in other cases, lose here all their distinctive effects, and are found alike inefficient and harmless. I doubt not that in some habits, and especially when the morbid cause is present in slight degree (a contingency ever to be kept in