morbid product at all, or that it was common to many different diseases. One case, however, is sufficiently suggestive to deserve further notice. Professor Hallier has discovered in the excreta of cholera a peculiar fungus, which he cannot find in any of the other "moulds" of Germany. It belongs to a variety of fungi, all of which come from Asia, and are parasites upon one or other of the cereals, like our smut in wheat, or ergot of rye; and he finds that this particular fungus attacks rice, and rapidly destroys it. He infers, therefore, that it is Indian in its origin, and believes it to be the cause of cholera. Putting microscopical evidence aside, there is curious evidence of another kind to connect a contagious disease with the existence of mouldy vegetable matter. In one case, in America, the fungus formed upon wheat-straw has been seen to produce true measles; and a similar instance has occurred in Dublin, where the same disease was produced by mouldy linseed meal. It may be right to mention, that this theory of the organic nature of contagious diseases is not the only one held at the present day. Dr. Richardson in England, and M. Robin in France-two eminent authorities-compare the phenomena of contagion, not to fermentation, but to the cases, well known to chemists under the name "catalysis," where one substance appears to change another by its mere presence. It is here sufficient to remark that the very nature of catalysis is very imperfectly understood, and that the analogy between it and contagion breaks down at this point, that the active agent in catalysis does not increase in quantity during the process, while the active principle in contagion multiplies with marvellous rapidity. Let us pass from the region of speculation to that of fact. What has been discovered by modern research as to the physical condition of the active contagious principle? There are strong anterior probabilities that it is in all cases solid; for, if it were a gas, it would follow the usual law of gases, and become equally diffused through all the surrounding atmosphere; while a liquid would be much more notably effected by changes of temperature, and by wind. Observation and experiment, as far as they go, depose in the same direction. The progress of contagious diseases, from bed to bed, in a hospital ward, seems to show the solidity of the infectious principle, and some experiments, very carefully performed last year in Paris by M. Chauveau, prove that in the inoculable diseases the solid part of the secretion only contains the poison. The ways in which the various animal poisons enter the body are different in different diseases. Some are "inoculated," that is, introduced into the blood by a wound, as, for instance, smallpox, cow-pox, erysipelas, and glanders; others appear to be always inhaled, and absorbed into the body from the lungsthese are typhus, measles, and scarlet fever; while others are swallowed in food or drink, and so produce their effects-such are yellow fever, enteric or typhoid fever, and cholera. Some important practical results might follow from these general rules, the proofs for which we have not space to detail. The inoculable diseases are to be guarded against by preserving the surface of the body from contact with the poison; the most striking examples of this are, the remarkable exemption from the plague of persons who handle fat or oil in their trade, and the danger of even a slight wound in a hospital where erysipelas is epidemic. The inhaled poisons are far more difficult to be avoided. Fortunately, an attack protects very decidedly against a repetition of the disease, and free ventilation very much diminishes the danger, both by mechanical dilution and removal of the poison, and also by its decomposition by the oxygen of the air. Beyond this we know of little that can be done, but, in regard of scarlet fever, Dr. W. Budd has recently made a very valuable suggestion. As there is strong reason to believe that the infection of scarlet fever resides mainly in the minute particles of the skin, which comes off in flakes towards the close of the fever, he proposes to keep the body constantly oiled and frequently bathed, as soon as this process of "scaling" begins. The poisons which are taken in food and drink are (omitting yellow fever) cholera and enteric (or typhoid) sever. It might be thought that nothing could be easier than to prevent such a way of contracting disease, but unfortunately this is not the case at present. The remedy is, however, in our own hands, and the importance of the object to be attained induces us to insist on some unpleasant details, which we would gladly have spared our readers. Enteric fever (generally confounded by the public with typhus. under the name of "fever"), is essentially produced by drinking. water contaminated with sewage.* * The bad drainage, and even * The medical reader (if such there be), will observe that we leave out of account two questions, of great importance in themselves—viz., the possibility of a "de novo" origin of the disease, and the effect of sewer gases in its production. They are omitted because they do not touch the main argument, and would occupy considerable space. worse water supply, of most of our smaller towns and villages, are the causes of the prevalence of this very fatal disease in places which might seem most healthy to a superficial observer. Probably, too, even in most of the cases where the disease is caught from another person, impurity of water supply and bad drainage are necessary conditions of its development. Cholera is a still more remarkable instance of the need of sanitary reform. Since the time of Dr. Snow, who first proved a distinct connection between the water supply and outbreaks of this terrible epidemic, a great mass of evidence has been collected, which seems to prove, almost to demonstration, that cholera poison is usually harmless as it leaves the body; that, if it is diluted with perfectly pure water, it remains quite inert, until its speedy decomposition entirely destroys it, but that when water containing any organic impurity (especially sewage) it rapidly develops its destructive qualities. These facts can readily be accounted for on the ordinary fermentation theory, and their practical value is equally obvious-the moral to be drawn being that if public opinion can be so far improved as to adopt everywhere good water supply and good drainage, these two diseases may most probably be entirely eradicated. Mr. Simon and Sir W. Jenner suggest that the zeal of local authorities might be admirably quickened by giving to all who have suffered, in their own person or those of their relations, power to recover damages from those whose neglect has been the cause of illness or death. Meanwhile, the only things which individuals can do are, to be very careful never to drink suspected water which has not been boiled, and to look to the drains and cisterns of their own houses. There are two other sanitary measures, which, if carried out by the concerted action of the community at large, would altogether remove the causes of two seriously frequent and fatal diseases. If overcrowding in the rooms of our poor were systematically prevented, there is very little reason to doubt that typhus feverthe scourge of our crowded cities, and especially of those where Irish congregate-would become a very rare disease. Or, again, if great distress, and what may be called chronic starvation, were unknown, the relapsing, or famine fever, would speedily disappear from Ireland, Germany, and Russia. But let us suppose that an individual has already, in any one of these ways, been attacked by a contagious disease. What means are to be taken to prevent its diffusion? It has been very well remarked that "just in the same manner as we should treat a savage animal we ought to treat an organic disease-we must either cage it, or destroy it." That is, we may either prevent any further organic change in the infectious principle, and so render it inert, or we may decompose it altogether. The first of these is effected by means of antiseptics, of which the chief is carbolic acid, a substance which has been largely used of late years in this country. The destructive disinfectants are far more numerous, and, on the whole, more generally useful. The chief and most powerful is oxygen, either in the shape of abundant fresh air, or as contained in the well-known "Condy's fluid; " next to this comes chlorine, a most powerful agent, which is generally obtained from chloride of lime; and then iodine, which may be allowed slowly to evaporate in the sick room. There are still great differences of opinion as to the relative merits of these various substances; probably, carbolic acid is most useful for the immediate disinfection of excreta, Condy's fluid for washing the hands after touching the patient, and chlorine or iodine for purifying the air. The clothes of patients suffering from such diseases are often put at once into hot water, whereby the infectious principle is more certainly spread than if they had been washed in the usual manner. They should always be put at once into cold water; after a time the water should be drained off, and they should then be plunged into quite boiling water, and kept there for half an hour. Chloride of lime may be added with advantage to the first water. We have not mentioned chloride of zinc and sulphate of iron among the disinfectants, because we believe they probably destroy only one of the inorganic substances present, which has no necessary connection with the real cause of disease. The principal means of resistance to the infection of all these diseases appears to be a healthy and vigorous state of the nervous system. Thus, the public are perfectly aware of the evil influence of fear or agitation as predisposing causes, and even exaggerate their importance so far as to be afraid of the fear of cholera. Probably the immunity of doctors and nurses from most of these diseases is in part owing to the confidence produced by habit; and the remarkable manner in which some epidemics (especially diphtheria) attack particular families, is perhaps due to some original weakness of the nervous system. An important practical corollary may be drawn from this general principle. Experience has abundantly shown that typhus fever is seldom acquired when the body is in its usual state of vigour, hence it should be an VOL. XI. GG universal rule never to visit a fever patient, if it can be avoided, when fasting or much fatigued. As to the mode in which contagious diseases are now treated, little can be said which would profit the general reader. As all diseases of this kind are now known to run a certain definite course, the physician does not attempt to check what is inevitable; he confines himself to treating symptoms as they arise and keeping up the strength of his patient, matters which have an easy sound in theory, but which, in practice, often tax to the full all the powers of an educated and discriminating judgment. Lines to a Faithful Friend. YES, my warm friend, the myrtle braid While affluence trims her waxen lights, Yes, let it laugh-'tis folly's hour; Thou on thy master's head meanwhile What though this morning's golden sun, The night, at least, my easy friend, And climb the distant hill ! |