quently made in treating of the "mild cases of endemic yellow fever"that, "the peculiar physiognomy of the malignant cases cannot be traced in these."

Surely here are very insufficient data given, upon which to base a diagnosis. Is there a pulse peculiar to yellow fever ?-and if so, what are its characteristics? Is it hard?-is it soft ?--is it large and hard? --is it small and hard?is it large and soft ?--(this we presume is the "bubbling" pulse) is it small and soft?-or, with any of these characters, is it quick or frequent, or slow? Is not any one of these, or any possible combination of these characters occasionally, found in the pulse in other diseases ?--and is not the moderately full and soft pulse the one most frequently found in the remissions of remittent fever? Is there invariably present a peculiar appearance of the eye in yellow fever?-or, is it not a fact, that the description of the appearance of the eye in this disease by one author, is in exact correspondence with that of another, of the appearance of the same organ in remittent fever?-—— We would ask, too, in what particular does the "restlessness" occurring in the remissions of yellow fever, differ from the restlessness, occurring during the remissions of remittent fever, or in other diseases, that the one should give evidence of the presence of a "hidden demon," and the other not? Now it is most evident, we think, that the result of the case in these instances was the only real ground of diagnosis. If, after having advanced to a certain extent, the progress of the disease was arrested, short of the occurrence of black-vomit,-recovery following,-the case was set down as one of bilious fever; but if black-vomit supervened, or if nature's efforts or "the usual antiperiodic remedies were unavailing ;" it was pronounced a case of yellow fever. No diagnostic symptoms then whatever, we think it will be admitted, are pointed out; for it is not pretended by any, that the yellowness of the skin and black-vomit are present even in all of the fatal cases of yellow fever; and Doctor Lewis himself says, that many cases terminated fatally in which this symptom, (black-vomit) was not present," and also," that in some who die as well as those who recover, the yellowness of skin is wanting."

Much stress has been laid upon the different degrees of susceptibility of different classes of persons to the two diseases, as a basis of distinction. We think that certain facts mentioned by Doctor Hewis, bearing upon this part of the question, by no means tend to support the view he has taken. It becomes necessary for us to repeat.

"During this calamitous season (the autumn of 1819) it would appear that every character of endemic febrile poison was poured in concentrated abundance upon the inhabitants, each one being active in its peculiar way in doing the work of death. The whites invariably died on the 4th, 5th or 6th day of black vomit. whilst the negroes and quadroons, after protracted suffering from bilious fever, resulting in frequent relapses, cold sweats and colliquative diarrhoea, shared the same fate. The equal prominence of bilious and yellow fever makes this a remarkable epidemic-the diseases however were respectively confined to different classes of persons."

Now is it not equally as reasonable to suppose, that in this epidemic there was but one poisonous agent of disease at work, and that the difference in the effects, on different classes of persons resulting there.

from, was owing to the modifying influence of constitutional peculiarities, producing in the case of the negro a partial insusceptibility to the action of the poison, by which that peculiar pathological change, whatever it be, resulting in black vomit, was prevented, as that there were two distinct poisons in operation, one for the blacks, and another for the whites, and respectively confined to these different classes?-Whatever opinions may have been entertained, in regard to the insusceptibility of the negro to the action of the poison of yellow fever, none have ventured to assert that the white man cannot have bilious fever. It is not unreasonable then to suppose, that in this violent epidemic the poison was of so concentrated a character, as to produce those peculiar pathological changes, resulting in black vomit, "invariably" in those of the white population who were attacked, and that something peculiar in the constitution of the negro protected him from the effects of the poison in so far as these changes were involved; while it would be most irrational and absurd to assert, that an epidemic remittent fever could prevail extensively among the negroes of a place without, in any instance, the poison, if distinct, affecting the whites; admitted as it is universally, that the latter class of persons is more liable to this disease also than the former. It may not be irrelevant to state in connection with the present subject, too, that it accords with the experience of Doctor Lewis, that the remarkable exemption from the yellow fever, which this race (the negro) enjoys, extends in a great measure to all the malarious fevers of hot climates."*

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'Every summer and autumn intermittent and remittent fevers prevail in these suburbs (those of Mobile), whilst those living in the middle part of the city, seldom have this character of disease, except in sickly years, and then the cases are confined to those that are acclimated, while strangers unacclimated suffer in the more violent form of yellow fever;" and, further on we find, that, during epidemics, many of the acclimated, among whom are those who have had the disease in former years, experience mild ephemeral attacks. If these statements of Doctor Lewis were allowed to speak for themselves, what would be their language? something like this we are induced to believe: that one poison only existed; that in healthy seasons, that is to say, when this poison is generated only to a moderate extent, and in a less concentrated degree, it produced intermittents and remittents only; and these confined to the principal foci of its production; but, that in "sickly years," that is to say, when a greater portion of the poison is generated, and in a more concentrated form, its ravages are extended to the middle parts of the city, producing there among the acclimated, including "those who have had the disease in former years," those whose susceptibility to its action has been diminished by long and gradual familiarity with it, intermittent and remittent fevers, and "mild ephemeral attacks of yellow fever, which, we think, according to the admission of Doctor Lewis himself, cannot be distinguished or separated from remittent fever, "while strangers unacclimated suffer, in the more violent form of yellow fever, from its action.

Doctor Lewis tells us, that " negroes rarely have the disease.” ***

* New Orleans Medical Journal for March 1845. Page 417.

"In late epidemics a few mulattoes only have experienced attacks, and these exceedingly mild, seldom arriving at the black vomit stage." In regard to this fact, is it not a reasonable inference, that a constitu. tional peculiarity exists, bestowing upon the negro an entire immunity from that peculiar action of the poison resulting in black vomit, which is diminished by the admixture of races in the mulatto! The negro, it seems, is not entirely exempt from the disease, though Doctor Lewis gives no instance in which black vomit occurred in one of the race; while in the mulatto, it is admitted that the black vomit does occur; the disease seldom however arriving at this stage.

"We pass on to the city of Mobile, and there discover, peculiar to her trodden animalized streets, yet another character of disease." This text leads us naturally to the consideration of the question, in how far the non-identity of the two diseases or forms of disease, remittent and yellow fever, is sustained, by a marked difference or peculiarity, as is maintained by some to be the case, in the character of the localities in which the latter is wont to occur. Although the remark above quoted is intended, we presume, to convey the idea, that yellow fever is peculiar to the "trodden animalized streets" of a city-there are certain facts mentioned in the essay before us, the true interpretation of which, we think, would lead to a different conclusion, and others, not mentioned, in the present essay, but of which, it will be seen, that Doctor Lewis was aware, proving most unquestionably the erroneousness of such a doctrine.

It is not pretended by any, we believe, certainly not by Doctor Lewis, that remittent fever does not occur in those localities, which seem more especially favorable to the development of yellow fever, and even during the prevalance of the latter disease.

"In 1826 Mobile was healthy and the town of Montgomery very sickly. In the month of August, two gentlemen came from the former place, visited the latter, snd after remaining a few days, were seized with remittent bilious fever, the disease of the place, and died on the 7th day of illness, of black vomit."-This fact is presented by Doctor Lewis with a very different intention from that with which it is brought forward at present,-to wit,-to prove the existence of two separate poisons, in action on the system at the same time.

Now, it will be recollected, that at the time named Mobile was healthy. Yellow fever then of course was not prevalent there, and consequently its producing agent had not been generated. How then could the mere fact, of these two young men having been in Mobile produce any modifying effects on a disease contracted in Montgomery, different from what might have been produced by their prior presence in any other healthy place? We anticipate the answer to this. It may be said, that although the poison of yellow fever had not been generated to a sufficient extent to cause the development of that disease, still there might have been a sufficiency of it received by these two young men, to exert a modifying influence over a disease of a different character, when once excited. But, before admitting this explanation, it is but reasonable that we should ask, whether all, or any of the cases of bilious remittent fever, which occurred in Mobile during this season,-for we take it for granted that no summer, even the most

healthy, since the settlement of the place, has ever passed in which more or less of this disease has not existed there,-terminated in black vomit, and if so, what were the diagnostic symptoms by which they were recognized as cases of bilious fever, and not yellow fever?

Moreover, as these two cases proved fatal during the presence of black vomit, an almost invariably fatal symptom of yellow fever, (admitting for the moment the non-identity of the poisons of yellow fever and bilious fever, and that they were both in operation on the system at the same time; remembering too the fact, that the latter is a much less fatal disease than the former); is it not reasonable to infer that the profound pathological changes preceding and resulting in this symptom, were those determining a fatal termination, and also that the symptoms resulting from the bilious fever poison would have been masked completely by those resulting from the deeper and more profound lesions of the yellow fever poison; in short, that the patients died of yellow fever?-Now, as Doctor Lewis merely tells us, that they were taken with remittent bilious fever," and died of black vomit, without giving us the symptoms by which they were identified, as cases of bilious fever, it is proper that we should remember the facts, to which we have already alluded, mentioned by our author, showing the exceeding difficulty of diagnosis in certain cases between yellow fever and our other forms of autumnal disease.

But these cases, we think, are susceptible of a different interpretation. "Mobile was healthy, and the town of Montgomery very sickly." The gentlemen then, leaving a healthy, were suddenly thrown into a very polluted atmosphere, and not possessing that partial immunity from the effects of the poisonous agent of the prevalent disease, produced by acclimation, or gradual exposure to its operation, as would naturally be expected, suffered the full extent of its influence, both as regards the number and profundity of the changes resulting from its action.

We may in the present connection mention a fact, quoted by Doctor Lewis himself on another occasion,* showing the occurrence of yellow fever in a locality very different from the "trodden animalized streets" of a city, but in passing, will refer also to the instance of its occurrence in the "little village of Woodville," with which, we are sure, he is familiar. ***"Père Dutertre, a historian who resided in the WestIndies in 1635 and who was a close observer, describes with great fidelity the disease that we now call yellow fever, and says: "Those who were chiefly attacked were employed in clearing the land, in different islands, and were exposed to the poisonous vapours and exhalations."

As a distinguishing characteristic between remittent and yellow fever, others who have adopted the view of their separate nature, have advanced, as confirmatory evidence in favor of their opinion, that one attack of the latter confers a complete immunity from it ever after, or at least that the protection thus afforded, is about as certain as that afforded by one attack of small-pox against any subsequent recurrence of this disease, in the same individual, and that this is not the case in

*New Orleans Medical Journal for July 1844. Page 43.

regard to remittent fever; but, the experience of Doctor Lewis is entirely subversive of this proposition, for he distinctly says, that "there can be no question that some persons have the disease the second, and some the third or fourth time."

In this mere partial immunity, established by Doctor Lewis, afforded by one attack of yellow fever, the observant practitioner, experienced in the treatment of remittent fever, will not fail to perceive a fact, strongly corroborative of the opinion of the identity of the two diseases, and that the former is the result of the same poison, in more concentrated action, and modified in its effects by attendant circumstances, as the latter; for, while it is well known that, though a patient may have several attacks of mild remittent fever, even in the same season, a recurrence of the disease very rarely succeeds a severe attack during the same year; in many not for several years, or until a renewed susceptibility is induced by a temporary residence in a non-malarious region, and in some never, though continuing to be exposed to the same causes and circumstances, productive of the disease in the first instance; and it will generally be found, too, that the immunity thus afforded will be proportionate to the violence of the previous attack. One attack of yellow fever, then, it may be urged, exercises not a complete protective influence, but one a shade more perfect only, than that afforded by such attacks of remittent fever, as merely fail to reach the grade called yellow fever.

But perhaps of all the arguments in favor of the non-identity of remittent and yellow fever, those based upon the supposition that each of the diseases was characterized by certain morbid phenomena discoverable after death, have been the most defective. The account of the supposed" anatomical characteristic" of yellow fever, given by Louis, after his examinations in Gibraltar in 1828, consisting in a certain degree of dryness of the tissue of the liver, attended with diminished depth of color, reducing it to a shade resembling that of sole. leather, mustard, straw etc., confirmed in the minds of many the correctness of the opinion of the distinct character of the disease; and the more recent observations of Doctors Stewardson, Stille and Swett, relative to certain appearances of the liver, found in the examination of some cases of remittent fever, altogether different from that described by Louis, and assumed by these gentlemen as an "anatomical characteristic" of the latter disease, have tended greatly to extend and strengthen this conclusion. The "anatomical characteristic" of remittent fever, as described by Doctor Stewardson, consisted in most instances, in a flabby state of the organ, with change of color; it being externally of a bronze or olive, or a mixture of these colors, internally of an olive color, with an entire extinction of the natural reddish brown, and "the two substances so blended as to be scarcely dis. tinguishable.”—Let us see how far the pathological researches given us by Doctor Lewis are in accordance with the opinion that the two diseases under consideration are marked respectively by a distinct and peculiar anatomical characteristic ?

Speaking of the "remittent, or according to a strict definition, continued bilious fever, **** commonly known as swamp fever," the author says: "In the examination of four bodies in the Hospitals of