that throughout our whole malarial middle country, and indeed somewhat, though less strikingly, in our lower alluvial districts, typhoid fevers are becoming more and more frequent in places and settlements, and under circumstances, where hitherto the ordinary autumnal remittents prevailed exclusively. In certain localities, the congestive forms of intermittent and remittent have seemed for the past eight or ten years to have been gaining ground, and now to be giving way in their turn to the newly observed type; and some physicians have regarded it as a sort of intermediate link between, or transition from, common malarious fever to the typhoid type.

This conversion or substitution-we shall lay no stress upon the word-is in certain instances supposed to be accounted for by the mere supervention of a peculiar condition of prostration, depression, im. pairment of vitality in the subject. This may result either from previous disease or from contingencies which act more obscurely upon the constitution without developing any open malady, giving rise, as we say, to a predisposition.

It is farther suggested that certain diseases, certain types of fever, possess a sort of relevancy or correlation, through and by means of which they determine or create a predisposition to each other. In a recent article in the British and Foreign Review, July, 1851, the writer asserts of the "relapsing fever" of Jenner and other English physicians, a newly recognized form of continued fever, that "it predisposes to typhoid, and that typhoid in turn predisposes to relapsing fever." It is easy to believe of these types, so closely correlated and connected, even if distinct, that they should be substituted by or converted into each other. Yet it is clear they cannot, as some have argued, be identical or the same, because typhoid does not predispose to itself, but notoriously indisposes, or diminishes if it does not take away the liability, to its own subsequent attack. It seems to me unquestionable that, in some sense, whether by mere protraction or specifically, all the known forms of idiopathic fever predispose to typhoid; at least all known forms of fever, if greatly prolonged, put on, as has been above stated, many features which belong to the usual description of typhoid, and sometimes lose all those which characteristically belong to their own average duration and less advanced stages; and which in some instances continue persistently to be strongly marked throughout the most indefinite protraction. This is true not only of those already spoken of, periodical fevers of every variety especially in the congestive form, but of yellow fever, catarrhal fever, nay, the consecutive fever of cholera, and the numerous pyrectic affections which occupy the doubtful ground of such connection with internal inflammations as to render their idiopathic character questionable, such as gastric, mesenteric, and verminous fevers, and the infantile remittents treated of specially by so many writers, and by so many refused a separate place in our nosological catalogues.

In Henle's view of "the transformation of intermittents into conta gious typhus and yellow fever," we find this doctrine distinctly stated thus: "By marsh air, sulphuretted hydrogen, negative electricity or any other cause, intermittent fever is produced; by the intermittent

the chemical constituents of the blood or other fluids become altered; by this alteration the individual is adapted to receive and support liv. ing bodies floating in the atmosphere, which then occasion a new form of disease, and at last the latter may proceed farther as a contagious disease." There are examples enough in which certain forms of fever appear to have led the way or predisposed in a similar manner to typhus-the true or Irish typhus of controversial writers. Ferguson says, "that the fever on board an infected vessel from Trinidad to Barbadoes, from crowding below decks at sea ceased to be yellow fever, and became as truly typhoid (typhus) as any he ever saw; but all that were taken ill after she came into harbor retained (regained?) the character of yellow fever in every respect, and showed not the least of the typhoid type. That the ship was impregnated with a typhoid contagion, capable of infecting others within its sphere," he adds, "I have not the slightest doubt." Here we may infer a mingling of the causes of the two, either of them predominating, as circumstances favored in turn; but, as it would seem, the cause of typhus was not efficient enough in amount or force to develop its influences except in those previously assailed by yellow fever.

Catarrhal fever not unfrequently determines a similar predisposition, and it is not rare to hear of cases of typhus that have commenced with catarrhal symptoms both sporadically induced, and of epidemic origin. A striking example of this transition, substitution, or conversion, occurred some years since in my own practice. A whole family were much exposed to cold and moisture at a forest camp-meeting held early in spring. They were attacked, all or most of them, with common catarrh, which in two, a mother and adult daughter, was attended with febrile irritation, rather violent and persisting. They were brought home, their house being an old one, ill lighted and ventilated, and standing in a narrow alley. After some protraction, the cases assumed all the appearance of true typhus. The friends who attended and nursed them were in several instances seized with the same low fever, and conveyed it to their families in separate and distinct parts of the city; twelve such cases, identical in character, and unquestionably all traceable to the two first mentioned, came under my treatment. No one doubted the contagious character of these attacks, and the history was much more impressive on that account. In southern practice there is far less opportunity to observe the efficient development of the property of contagiousness in disease generally, than in the colder regions of the north. The domestic architecture is modelled chiefly to alleviate the heat of our long summers, rather than to shelter us in our short and genial winters; every arrangement is usually made in houses of the middle and better classes for the most profuse ventilation of every apartment. Large and numerous windows yield an abundance of light too as well as air. All offensive excreta are, therefore, if dif fusible in the atmosphere, largely diluted and promptly dispersed, and maladies depending upon ochlesis, either primarily or as concurrent in its influence, apt to be efficiently counteracted. If there be anything, however, which may be dwelt on as proving conversion of type, it is, we repeat, this change in the character of the specific causation

from any other generative or creative force, to the peculiar, vital, germinal matter of contagion. This took place indisputably in the instance above related. In the African reports nothing is more common than the repetition of similar statements. "Remittent fever," says Bryson, "frequently breaks out in vessels at anchor, in the ports and rivers, especially if the crews land or are detached on boat service. Under these circumstances it often becomes virulent, and in a few instances seems to have acquired contagious properties."

Sir W. Burnett, speaking of the notorious fever of the Bann at the Island of Ascension, considers it to have been "originally the common endemic of the country, which became contagious subsequently to the state of the weather preventing ventilation, and from a great number of the sick being confined in a small place." In this view of the matter, his reasonings closely correspond with those by which Ferguson explains the conversion of yellow fever into typhus.

But the most remarkable, and one of the best confirmed in medical writings, is the alleged conversion, on board the British steamship L'Eclair, of the endemical fever of the African coast into a singularly malignant form of contagious fever, to which the title of yellow fever, the true hæmagastric pestilence, has been given in the journals, but recently filled with the controversial discussions which its interesting history has provoked. This vessel, after suffering some months from African fever on the coast, "distinctly remittent," anchored in August, 1845, at the island, previously healthy, of Boa Vista. There the disease, which had been growing more and more malignant and fatal, assumed all the terrible characteristics of yellow fever, affording decided proofs of contagiousness, spreading on shore from place to place, adhering to the vessel and attacking all who joined her, until her return to England in October; the English pilot and a surgeon who came on board of her, being the last of the deaths.

Numerous similar instances might be added, but these shall suffice. Such histories are pregnant with profound pathological and philosophic interest. If contagious diseases can be generated under any contingency whatever (and who doubts the possibility of this occurrence?) and if the matter of contagion is a vital individuality, a self-multiplying germ capable of indefinite reproduction, then the creation or development of this new cause must give rise to new results. A new form of disease presents itself, which either blends with that which pre-existed, or supplants and substitutes it. If the causes are connate and correlevant, "blending of type" takes place, and especially if they are nearly or quite equal in force, and circumstances do not favor the one at the expense of the other. But if they be strongly dissimilar or contrasted, or in any sense incompatible, or if circumstances foster the one and repress the other, then there will be the subversion of the first, the weaker, and we shall have conversion of type in the only sense possible and intelligible.

IDIOPATHIC FEVERS.

Idiopathic fevers are divided into the intermittent, remittent, and continued, of which I proceed to treat successively, and in order as I have named them.

The intermittent consists of a series of febrile paroxysms, separated from each other by, distinct intervals of apyrexia.

The remittent, as its name imports, does not present any interval absolutely apyrectic; it is characterized by the occurrence of definite periods of abatement, or diminution of the febrile symptoms, followed by a return or aggravation of them.

Continued fever has been denied a separate existence. It is, perhaps, difficult to imagine a fever so equable in its course, and steadily continuous, as that it shall offer no variation in the degree of violence of symptoms from time to time; yet there is such an obvious and well marked difference between the occasional and uncertain occurrence of such abatement, and the regular, calculable, and characteristic remissions of our second class, that I do not hesitate to recognize the distinction. It appears to me, indeed, as difficult to confound the types of the ordinary remittent fever of our climate and of typhus, as it would be to mistake a quartan for a bilious remittent.

The intermittent has been supposed by some to be the primary type, from which each of the others originates, liable to certain complexities and modifications. This idea is by no means destitute of plausibility. I shall hereafter point out the relations between the remittents of our climate and the varieties of the tertian. Thus, too, the quotidian has been considered the source of the continued fevers, and if we pursue the analogy, we shall be able to shadow forth a vague and indefinite relation of critical days to the quotidian in the first week, the tertian in the second, and the quartan in the third. Nor need we stop in these our fanciful calculations, until we have traced all these periods of exacerbation, remission, and crisis to diurnal and septenary revolutions, and these to the influence of the sun and moon.

INTERMITTENT FEVER.

The paroxysm of an intermittent consists of three stages-the cold, hot, and sweating-the first of which may be regarded as the invasion, the last, as the solution of a febrile attack.

At the commencement of the cold stage, the patient is affected with a sense of languor and muscular weakness; yawns, stretches, and perhaps sighs frequently; his face is pale, his lips bluish or livid, and his features are shrunken. The feeling of cold commences along the course of the spine, as if water were trickling down his back; the extremities are next affected, and the sensation soon extends over his whole body, becoming often so intense as to occasion corrugation of the skin and "rigors," and chattering of the teeth. These symptoms

are attended with tremulous shivering of the body, gastric oppression and nausea, and often with headache and spinal and muscular pains.

When they have lasted for a certain length of time, flushings of heat begin to alternate with the rigors, the uneasiness of stomach increases to vomiting, and finally the sensation of heat predominates, and the second stage supervenes, with turgid features, red and watery eye, restlessness and thirst. The pulse, which was at first contracted and apparently feeble, now becomes full, hard, and bounding. The matters vomited, after the stomach has been emptied of its accidental contents, consist of a mixture of mucus and vitiated bile. The duration of this hot stage varies according to circumstances, but at length a moisture is thrown out upon the forehead and breast, which progressively extends over the whole body; and the sweat flowing freely, all the symptoms subside, and are soon entirely relieved.

Such is the ordinary history of the paroxysm of an intermittent, but we meet, in reading and practice, with many irregularities and anomalies. It is not uncommon, for example, to see intermittents without any rigor or cold stage; and some cases of considerable protraction have preserved this peculiarity throughout their whole course.

The books tell some strange stories of these anomalies. Instances are recorded in which the hot stage was known to antecede the cold; nay, one is given from Schenck, in which the usual order of the paroxysm was completely reversed, and the sweating stage took precedence.

Much is said by authors of what they term masked or disguised intermittents, in which all the usual phenomena of the febrile paroxysm are absent, and others substituted in their stead, by means of some inexplicable association. It is urged as a matter of great importance to discern and distinguish such cases, as the proper treatment of intermittents is alone capable of effecting their cure. A pain in the eye, in the head, the abdomen, in one limb, etc., has been observed to recur at regular intervals, and to bid defiance to. any other mode of management. It is further alleged that those attacks are occasioned by the specific cause of intermittents, malaria namely, or paludal miasmata. Granting, however, what I am not called on here either to affirm or deny, the identity of the cause producing them with that of intermit tents, I am still doubtful of the propriety of classing them under this head; but would prefer to regard them as affections of the parts in which they show themselves, presenting in addition to their usual symptoms the remarkable one of periodical recurrence. We shall find the received catalogue of malarious diseases to be far from a short one, and even where this obscure but powerful agent has not been, to speak correctly, the efficient cause of any disease, it may impress the attack with the character of periodicity either by direct modification, or by the constitutional predisposition it has generated.

But periodicity itself is not so rare a circumstance in the history of diseases as to require that we should refer such as manifest it, to the head of intermittent fevers on that ground exclusively. All classes of disorders may assume a periodical regularity. In 1821, there was a man in our almshouse, whose case was looked upon as a "masked