they are found travelling up hills of moderate elevation, the ascent of which is very gradual; and this holds good, from whatsoever source they may have arisen. Whilst excavations were making at the Cimetiere des Innocents at Paris, this poison was found in the cellars of some of the neighbouring houses, in such quantities, mixed up with other gases, as to produce asphyxia in those exposed to them; and of those who recovered from the first effects, many died from malignant fevers produced by its absorption into the body.

Though we must come to the conclusion, that we know nothing of the nature of this poison, we must not, on that account, deny its existence, nor its identity in every case, from whatever source it may have risen. When we study its physiological effects on man, or some of the lower animals, we shall still farther be convinced of this truth, that in no respect does it present any other difference than that of intensity, or perhaps some slight modifications arising from its source, its producing causes, and the substances with which it may in different cases be combined.

PHYSIOLOGICAL EFFECTS OF MALARIA.

This subject may be divided into two heads. First, the effects of marsh effluvia expanded through the atmosphere on the mass of an acclimated population. Secondly, the effects produced on individuals by this poison in a concentrated form.

Effects of Malaria on an acclimated Population.

These effects are not the same in all countries, for each climate has its own temperature, and other causes which powerfully influence those of malaria. The people of Holland have not the same character and appearance as those near Rome; nor do the latter resemble altogether the inhabitants of St. Lucia.

The inhabitants of marshy countries, where the temperature is moderate, present the following appearances:-The skin is pale, livid, or yellow, the eyes dull and heavy, the movements

of the body slow and languid, the eyelids and face puffy and somewhat swollen, or shrunk and wrinkled at an age when they ought not to be; the abdomen large, the extremities small, shrunk, and wanting consistence in the muscles; the sensations both of pleasure and pain seem deadened; common events produce little effect, exciting neither joy nor sorrow. They present the lymphatic, or, as it was formerly called, the leuco-phlegmatic temperament, in its greatest developement. Cadavaric inspection shows us chronic engorgements or morbid changes of structure in some or all of the viscera. Acute inflammations are rare, but living in an unwholesome atmosphere, they never enjoy health; they are always valetudinarians. How can it be otherwise, attacked as they so frequently are by intermittent or remittent fevers, which though so slight as to be treated by the unfortunate beings who have served a long apprenticeship to suffering, with indifference, nevertheless ultimately produce premature old age and death? They suffer from neuralgic affections; sciatica and tic doloureux are common; their blood is thin and watery, giving rise to ulcers of the legs and scurvy.

As we approach the tropics, though the lymphatic temperament still obtains, we find it combined with a greater excitability of the nervous system; and within these regions are added irritability of the skin and of the abdominal viscera. There is a strange mixture of indolence and love of excitement: a wish to be roused from the listlessness of every-day life, but requiring a powerful stimulus to effect it. Slight causes produce affections of the nervous system which terminate in death. Colic, followed by paralysis of some part of the body, is common; and hysteria and other diseases of this class are frequently combined with the ordinary disorders of the country. We can account for this only by admitting a peculiar modification of the ordinary morbific agents, or a peculiar idiosyncrasy in the people.

When acclimated individuals are exposed to the emanations from marsh in a more concentrated form, or in a greater quantity than their powers are capable of resisting, they are attacked by the same diseases as the unacclimated.

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Differences in the manner of, and situation in life, influence the temperament of the inhabitants, and consequently their diseases. The population of St. Lucia consists of English, French, Creoles of both white and mixed races, and negroes. The better classes, who live well, drinking good old wine and eating food both nourishing and easily digested, preserve a temperament more or less sanguineous; and though occasionally attacked with fever or affections of the abdominal organs, are not subject to those chronic engorgements of the viscera which I have mentioned. Some of the poorer French or their descendants, white or coloured, who are badly fed and naturally abstemious in their mode of living, taking only small quantities of an inferior red wine mixed with water, present examples of a developed lymphatic temperament, and their diseases are of that class. Dram-drinkers of all races are subject to organic læsions of different viscera in a chronic form, and to derangements of the nervous system; they are liable to fevers, and when attacked generally sink under a train of ataxic symptoms.

An English gentleman of a sanguineous temperament married a French lady. He was attacked with a mild intermitment, which was cured by diet and demulcent drinks. Fancying that his former method of life produced his disease, he determined upon living very abstemiously for the future, and his resolution was strengthened by the advice of his wife and her family. Madeira was exchanged for a common poor French wine, which he took diluted in large quantities of water; animal food, for the indigestible vegetables of the country, and a small proportion of fish. This system was continued for some time, until his abdomen and fat began to swell; to combat which he discontinued his wine, took large quantities of tisannes, several clysters, and a smart purge twice a week. In about a month he came up to town, and I saw him with my friend Dr. Drivon, when he presented the following appearances:-Anasarca from head to foot, effusion into the cavity of the peritonium. He was sitting up, his back supported by a chair, the body bent slightly forward; his breathing, short and rapid, consisting of a succession of

gaspings for air, could not be performed in any other position. Percussion of the chest impossible, from the immense effusion into the cellular tissue; neither the pulse at the wrist nor the stroke of the heart could be felt, for a similar reason. By change of diet this patient recovered and returned to England, where I lately saw him in rude health, and effectually cured of tisannes and abstinence.

By abstinence from a sufficient quantity of nutritious food and a moderate allowance of good wine, instead of dropsy we occasionally find that some painful neuralgic affection arises, and is only made to subside by returning to the former manner of life.

Dr. Levacher, in his "GuideMedical des Antilles," describes a peculiar kind of dysentery occurring in negroes or other people who have passed their lives in the neighbourhood of marshes, which he denominates, from its combination with other symptoms, "scorbutic." It may be added that where It these dysenteric symptoms are not found, others arising from the same cause occupy their place.

The effects of Malaria in a more concentrated form on Individuals.

Two ways of examining this subject present themselves to us; the first by observing its effects upon men and animals exposed to its influence; the second by experiments made on those animals which, like man, suffer from these emanations.

An European, or a native, after a long residence in a temperate and healthy climate, arriving in St. Lucia, complains of a feeling of weight in the atmosphere,-a something which resists the wish for exertion or exercise. Both his mind and body are oppressed; his intellect is clouded; his spirits are low and desponding, and all pre-existing love of enterprize vanishes. If his residence be protracted he has slight febrile movements, which come on regularly or irregularly, not sufficiently severe to prevent him pursuing his usual avocations, but which, nevertheless, are sufficient to induce him to throw

himself upon a sofa, and require a powerful effort of resolution to combat. In this manner his body may gradually accommodate itself to the climate, but he may consider himself fortunate if he escape so easily; in general, particularly if he be guilty of any imprudences, he feels restless at night, and can only sleep during the cool of the morning; he feels out of sorts; has pains in the back and extremities, as if from fatigue; he complains of head-ache, sickness, and nausea; and if these symptoms are not attended to immediately, suffers what is vulgarly called an attack of seasoning fever.

When the constitution is affected by malaria in a still more powerful manner, the effects are often immediate, and I will describe them as they occurred to myself. I had occasion to visit an estate in the neighbourhood of Castries about midnight, and my road obliged me to pass the swamp which lies to the north of the town. There was a lovely moonlight, the sky was unclouded, and a heavy dew was falling. On approaching the swamp I was sensible of an extremely disagreeable odour, arising from its emanations, and from the dank and foul vegetation on its surface and in its neighbourhood. I then perceived a peculiarly unpleasant, but indescribable taste in my mouth and pharynx, which produced slight vertigo, nausea, and even efforts to vomit. On my arrival at the estate, which was shortly afterwards, I took a glass of hot punch, with the hope that it would allay the nausea; I was, however, mistaken, for it was immediately rejected, and an ague came on, which obliged me to go to bed, where I remained until the afternoon of the following day. After a profuse perspiration I was enabled to ride to town, through still very unwell. At night the symptoms returned with such severity as to require a bleeding from the arm and leeches to the epigastrium; by these means the paroxysm subsided eighteen hours after its commencement, and a return was prevented by the free use of the sulphate of quinine. Both before and since I have passed this swamp at all hours without inconvenience, except from the unpleasant smell which always existed. I have also twice passed the Pontine Marshes at night, at a time when fever was raging in the Campagna,