In this relation, the remarkable experiments of Dr. G. Polli, of Milan, merit particular notice. They were made on dogs. into the veins of one he injected pus, which was followed by symptoms of pyaemia or purulent infection, with multiple abscess. into a second he injected putrid matter, and produced an attack of septicaemia, marked by typhous phenomena, with gastro-enteritis, and extensive intestinal ulceration. To a third the contagious matter of glanders was administered in the same manner, and was followed by an attack of that disease. He thus satisfied himself, that these various affections were owing to a specific poison in the blood. The question then occurred whether it might not be possible to neutralize these specific poisons, and thus prevent their action on the system. To solve this question, he had recourse to sulphurous acid and the sulphites, which were known to arrest all forms of organic fermentation, and of putrefactive metamorphosis of animal solids and liquids. Having first proved their entire want of injurious influence on the healthy animal, he selected several dogs, and, having administered one of these salts to a portion of the animals, and none to others, he injected the poisonous material as before, and found that, while the unprotected animals were destroyed by it, those to which the antidote had been given in small quantities suffered moderately from the poison, while those to which it had been given largely escaped entirely. Hogs, moreover, in which putrid blood was injected, previously diluted with a solution of the sulphite, were saved by this precaution. These experiments seemed to determine the possibility of protecting the system against the fermentative poisons. They were sufficiently conclusive to justify Dr. Polli in claiming for certain antizymotics the power of favourably modifying, perhaps of arresting or preventing all that class of diseases which, whether contagious or not, are produced by the absorption of a specific poison having the fermentative character. Experience has not yet been sufficient to warrant a positive decision in favour of the views of Dr. Polli, to their full extent; but the reports made by those who have given the antizymotic agents a fair trial are so decidedly to their advantage, that we may be justified in hoping for the most favourable results. When treating on sulphurous acid and the sulphites, the opportunity will be offered of entering more into detail in relation to their action. Hitherto the remarks concerning them have been merely illustrative of the general subject under discussion.

Though there are many substances which are known to act as poisons to the lower forms of organic life, yet there are but few which are admitted into the present class, because it is requisite that they should possess this power, without at the same time being noxious to man, so as to prevent their application. Arsenic and corrosive sublimate are parasiticides, yet in order to produce their effects when internally administered, they must be given in quantities which would be fatal to the patient. These substances, and others like them, may be and are frequently used in embalming, and in preserving bodies for dissection, but they do not strictly belong to the class of remedies we are now considering. The antizymotics here recognized, may all be ranked in two sets, one represented by sulphurous acid and the sulphites, the other by carbolic and cresylic acids and creasote. These will be fully considered. Should others seem to claim some notice, they will be briefly referred to in a subordinate position.

Heat is among the most efficient antizymotics, if sufficiently elevated. At the temperature of boiling water, almost all living things perish; so that an effectual method of treating clothing, bedding, and all other materials which may have been contaminated by contagious matter from the sick, or been exposed to an atmosphere pervaded by the animated causes of disease, and may thus contain the germ of any morbid fermentative agency, is to boil them in water, or to expose them in an oven to a heat of at least 212°. According to Pasteur, however, who is one of the highest authorities on this subject, there are fungi the spores of which will support a boiling temperature, and to destroy which it is necessary to expose them to a heat sufficient to decompose them. But such fungi have not, I believe, been recognized among those which are capable of producing disease in man; and, should their existence be suspected in any case, the heat necessary for their destruction can easily be commanded.

Extreme Cold always suspends fermentation; and hence epidemic diseases dependent on aerial poisons are generally checked in winter. Such is the case with cholera, yellow fever, and malarial disease; and in some instances the germs appear to be completely destroyed, so as not to revive on the return of warm weather. This seems to be particularly the case with those which are indigenous in tropical latitudes, and only occasionally, under peculiarly favourable circumstances, make inroads into colder regions. Generally, however, the winter only prevents their development without destroying their spores or ova; and, with favouring influences, these may be developed with the returning warmth, and resume their fatal activity. Still, it will always be advisable to avail ourselves of the antizymotic agency of cold; and whenever any disease has prevailed traceable to such a cause, dwellings of all kinds which may possibly have been infected, should, after the removal of the sick, be freely exposed, for a certain time, to the coldest air of winter. Had such a precaution been taken at Moscow, where on one occasion the cholera survived the winter, in consequence of the summer heat which is constantly maintained, during the cold weather, throughout their immense dwellings, the experience of that city would probably have corresponded with that of all the other large towns, in cold or temperate latitudes, in which winter puts an end to that fearful epidemic.