ORDER I. Pyrectica. Fevers. Remote causes. ganized matter de composed, essentially the same ed in some of its pro perties. Chief dif ferences be tween them. Impure air necessary for an extensive spread. or two of its qualities by the co-operation of the heat, moisture, stagnant atmosphere, and perhaps some other unknown agents, that are necessary to give it birth or activity.. The chief difference produced in this miasm under these distinct modes of origin is, that when generated by the decomposition of effluvium issuing from living but modifi- human bodies, it is less volatile *, and has at the same time a power more directly exhausting, or debilitating the sensorial energy, than when generated by the decomposition of dead organized matter. Whence fevers originating in jails or other confined and crowded scenes contaminate the atmosphere to a less distance than those from marshes or other swamps, but act with a greater degree of depression on the nervous system when once received into it. Yet even the latter have a definite atmosphere of action, beyond which they lose their power, and an atmosphere of a more limited diameter than we might at first be tempted to conceive: for we learn from Sir Gilbert Blane that in the unfortunate expedition to Walcheren, the crews of the ships in the road of Flushing were entirely free from the endemic of the country, as were also the guardships which were stationed in the narrow channel between Flushing and Beveland; the width of which channel is only about six thousand feet † In whatever mode derived, the remark of my excellent and distinguished friend Dr. Hosack will still hold, not indeed that it is altogether incapable of taking effect in a pure atmosphere, but that "an impure atmosphere is indispensably necessary to extend the specific poison.”‡ And I should also fully concur with himself, and Professor Brera § in censuring the application of the term epidemic to any of the febrile diseases hereby produced, Hist. and Cure of Fever, by R. Jackson, M.D. Part 1. Ch. 1. p. 102 † Select Dissertations, &c. p. 107. 40 to onda Observations on the Laws governing the communication of contagious Diseases, 4to. New York, 1815. § De' Contagi e della cura de' loro effetti, Lezioni Medico-pratiche del Cavaliere Brera, M.D. &c. 2 Vols. 8vo. Padua, 1819. causes. provided this epithet were usually confined, which I am ORDER I. Pyrectica. not aware of, to disorders supposed to result from some Fevers. primary intemperament of the atmosphere itself: and Remote provided also every attempt at distinction were not likely to perplex rather than to simplify a subject sufficiently intricate ab ovo; of which M. Devèze has furnished us with an ample specimen in his late treatise *. of Hosack. Why a corrupt state of the atmosphere should be Why an impure necessary to the general action of the febrile miasm, is a atmosphere question which still remains to be discussed. Dr. Ho- necessary. sack supposes that the latter "produces its effects by Explanation some chemical combination with the peculiar virus secreted from the diseased body”, and which is floating in the atmosphere: of the nature of which virus, however, he has not given us any information; while Dr. Chisholm Of conceives that it is the impurity of the atmosphere itself which operates by "increasing the susceptibility of the system to the action of the poison introduced". But to this explanation Dr. Hosack successfully rejoins, "that the predisposition of those who are most exposed to such impure air is less, while those who reside in the pure air of the country are most liable to be infected when exposed to the contagion." The true state of the case appears to me as follows. In a pure atmosphere, the miasmic materials easily become dissolved or decomposed; but slowly and with great difficulty, perhaps not at all, in a corrupt atmosphere, already saturated with foreign corpuscles. In a state thus crowded, moreover, they less readily disperse or ascend beyond their proper periphery of action; and perhaps by their tenacity adhere to bodies more ponderous than themselves, and thus loiter for a still longer period within the stratum of human intercourse. And as it is from the same tenacity they adhere to various kinds of clothes and filth, we may easily perceive why on the shaking or agitation of such substances, as in clearing a • Traité de la Fievre Jaune. p. 354. 8vo. Paris, 1820. Chisholm. Explanation offered by the author. ORDER I. ship's hold or unpacking its cargo, a pestilence may be Pyrectica. generated of which the crew have hitherto given no Fevers. Remote causes. Objections avoided by this expla nation. Origin and laws of febrile mi asm. signs*. Upon this explanation it is not necessary to suppose that febrile miasm has a power either of concentrating its virulence +, so as to render itself more active; or of multiplying its own form, so as to increase its numerical strength; against both which views, there are weighty objections. Every distinct particle thus suspended, and withheld from dissolution, becomes an active individual in the field of battle, and is almost sure to grapple with its man. So that hereby alone we have à force equal to any degree of mortality that can be conceived. While, then, the remote causes of fever are of different kinds, its chief and most effective is febrile miasm ; the origin and laws of which, so far as we are at present acquainted with it, may be expressed in the following corollaries : 1. The decomposition of dead organized matter, under the influence of certain agents, produces a miasm that proves a common cause of fever. 2. The whole of these agents have not yet been explored; but so far as we are acquainted with them, they seem to be the common auxiliaries of putrefaction, as warmth, moisture, air, and rest, or stagnation. 3. The nature of the fever depends, partly upon the state of the body at the time of attack; but chiefly upon some modification in the powers or qualities of the febrile miasm, by the varying proportions of these agents in relation to each other, in different places and seasons. And hence, the diversities of quotidians, tertians, and quartans; remittent and continued fevers, sometimes mild and sometimes malignant. 4. The decomposition of the effluvium transmitted from the living human body, produces a miasm similar to that generated by a decomposition of dead organized * Blane, Select Dissertations, &c. p. 307, Lond. 1822. Jackson, ut suprà, Part 1, Ch. x. p. 246. matter, and hence capable of becoming a cause of fever ORDER I. under the influence of like agents. Pyrectica. Fevers. causes. 5. The fever thus excited is varied or modified by Remote many of the same incidents that modify the miasmic principle when issuing from dead organized matter; and hence a like diversity of type and vehemence. 6. During the action of the fever thus produced, the effluvium from the living body is loaded with miasm of the same kind, completely elaborated as it passes off, and standing in no need of a decomposition of the effluvium for its formation. Under this form it is commonly known by the name of febrile contagion. In many cases, all the secretions are alike contaminated; and hence febrile miasm of this kind seems sometimes to be absorbed, in dissection, by an accidental wound in the hand, and to excite its specific influence on the body of the anatomist. 7. The miasm of human effluvium is chiefly distinguishable from that of dead organized matter, by being less volatile, and having a power of more directly exhausting or debilitating the sensorial energy, when once received into the system. Whence the fevers generated in jails or other confined and crowded scenes, contaminate the atmosphere to a less distance than those from marshes and other swamps, but act with a greater degree of depression on the living fibre. 3. The more stagnant the atmosphere, the more accumulated the miasmic corpuscles from whatever source derived; and the more accumulated these corpuscles, the more general the disease. 9. The miasmic material becomes dissolved or decomposed in a free influx of atmospheric air; and the purer the air the more readily the dissolution takes place: whence, è contrario, the fouler as well as more stagnant the air, the more readily it spreads its infection. 10. Under particular circumstances, and where the atmosphere is peculiarly loaded with contamination, the miasm that affects man, is capable also of affecting other animals. ORDER 1. Fevers. Remote causes. 11. By a long and gradual exposure to the influence Pyrectica. of febrile miasm, however produced, the human frame becomes torpid to its action, as it does to the action of other irritants; whence the natives of swampy countries, and prisoners confined in jails with typhous contamination around them, are affected far less readily than strangers; and, in numerous instances, are not affected at all. Doctrine of crises. Crisis, what sent day. Primary meaning and use of the term. 12. For the same reason, those who have once suffered from fever of whatever kind hereby produced, are less liable to be influenced a second time; and, in some instances seem to obtain a complete emancipation. It only remains to offer a few remarks upon the DOCTRINE OF CRISES; or that tendency which fevers are by many supposed to possess, of undergoing a sudden change at particular periods of their progress. A sudden and considerable variation of any kind, in the pre- whether favourable or unfavourable, occurring in the course of the general disease, and producing an influence on its character, is still loosely expressed by the name of crisis. The term is Greek, and pathologically imports a separation, secretion, or excretion of something from the body; which was in truth the meaning ascribed to it when first employed, agreeably to the hypothesis of concoction which we have just considered. The original hypothesis is abandoned; but the term is still continued in the sense now offered. "If the matter of the disease”, Professor Frank, "be expelled by some one convesays nient outlet, in the skin, kidneys, bowels, or blood-vessels, the crisis is simple; if by several of these at the same time, it is compound; if the whole be carried off at once, it is perfect. If it be carried off at different times, it is a lysis, or resolution." Critical distinctions of Frank. Crisis often occurring in the modern sense of the term. That changes of this kind are perpetually occurring in the progress of continued fevers, must, I think, be admitted by every considerate and experienced practitioner. Nothing is more common than to behold a pa• Brera, De' Contagi e della cura de' loro effetti, &c. ut suprà, Padua, 1819. De Curandis Hominum Morbis Epitome, &c., Tom, 1. De Febr. P. 26. |