BY F. W. HUNT, M.D., NEW YORK.

We have seen that the conditions necessary for the development of this disease consist of dead organic matter, resting on or blended with the mineral elements of the soil; “water, not in any but a certain quantity; and a temperature above 60 degrees of the thermometer, and continuing for at least two months.” That these conditions are all indispensable to the production of the fever is shown by the fact that “the absence of any one of them puts an end to the prevalence of the fever.” We proceed to enquire

What is the efficient cause of this disease? It was observed in the earlier ages of the world's history, that certain febrile diseases were more prevalent in some localities than in others; and that these same diseases were always associated with stagnant surface water, containing decaying vegetable matter dispersed in the atmosphere by the heat of the sun. They employed the word Miasma, (from a Greek word meaning “to infect or polute,”) to designate any infectious or contagious matter, but they made little effort to investigate the more intimate nature of any of these poisons.

In 1717, Lancisci, an Italian author employed the term Marsh Miasma, or Malaria, to express more definitely the specific cause of Intermittents; and since his time it has been generally considered as consisting of certain exhalations, or fine particles of decaying organic substances floating in the air, and highly deleterious to health. The correctness of this view of the subject was first questioned by Dr. Ferguson in a publication “On Marsh Poison” in 1821. Dr. Ferguson had been attached to the Medical Staff of the British army in the Peninsular War, and had seen Intermittents and Remittents in places where there was no vegetation then growing, or in any visible state of chemical decomposition. And, as men at that day looked no farther than to chemical theories for the explanation of vital phenomena, he came to the conclusion that vegetation and vegetable decomposition could have nothing to do with ague. He had been with the army with which Wellington. (Wellesley.) had defeated Joseph Bonaparte in one of the hottest days of July at Talavera: and, a few days after the battle, He saw the same veterans shaking with ague and dying of fever on the parching sands, between stagnant pools in the Red of the Guadiana river. He says

“The country around was so arid and dry for want of rain, that the Guadiana itself and all the smaller streams had in fact ceased to be streams, and were no more than lines of detached pools in the courses that had formerly been rivers: and there they suffered from remittent fevers of such destructive malignity that the enemy, and all Europe believed that the British host was extirpated; and the superstitious natives, though sickly themselves, and unable to account for disease of such uncommon type among the strangers, declared they had been poisoned by eating the mushrooms (a species of food they hold in abhorrence) which spring up after the first autumnal rains about the time the epidemic had attained its height.”

Now when we remember that this river originates in a region of marshes; that all its waters are saturated with vegetable matter from those widely spread swamps, in which the river Gaudiana itself is so far lost that for a distance of fourteen miles the current cannot be found; that the excessive heat of Summer had just evaporated the great mass of the water, depositing all its organic contents on the damp and drying surface of the bed of the river; that the low places in the river formed pools of stagnant water, still in the course of evaporation; we must see that all the conditions ever supposed to be necessary to the generation of Malaria in its highest potency were found in the most deadly combination in the spot selected for the encampment of the British Army.

Unable to recognize in the exhalations of the bed of the Guadiana any visible or tangible vegetable materials, Dr. Ferguson decided that no such thing existed there; that vegetable decomposition was not necessary to produce the disease: “that the peculiar poison may prevail where there is no decaying vegetable matter, and no vegetable matter to decay:” and that for its production “all that is necessary is a surface capable of absorbing moisture, and that this surface should be flooded and soaked with moisture and then dried; and the higher the temperature, and the quicker the drying process, the more plentiful and virulent is the poison that is evolved.”-(Edinburg Phil. Transactions, 1821.)

We find here no opinion on the specific cause of endemic fevers; but the facts given by Ferguson have continued, to the present time, their influence over medical men, not in furnishing them with any definite view of the nature of this “virulent poison,” but in leading them to seek for it in any direction whatever, except in decomposing vegetable matter. Some of the ablest writers of a later time, confused by the multiplicity of facts presented by their own observations and those of others, have abandoned all theories that have in view any specific Miasm; and declare that there is no such thing as Malaria; and that other well known and appreciable causes are sufficient to account for all that has ever been seen or suffered from Malarious fevers. This view of the subject was announced and ably defended by Dr. Bell of Tennessee, thirty years ago.-(Phil. Jour. Med. Science.) More recently Dr. Gayley of Virginia, starting from a different series of observations, has reached substantially the same conclusions, He says:

1. That the lungs and liver are the great decarbonizing organs of the body; and the functions being complementary, the activity of that function is always in an inverse ratio.

2. During winter, and in cold climates, the lungs are more active in consequence of their employment in generating a larger supply of animal heat. In summer the liver is the more active organ.

3. Exposure to cold repels the blood from the surface. In winter it is driven principally upon the lungs; in summer the congestion falls more generally on the liver, and we see as its result, derangement of those organs, the blood from which, has to pass through the liver to reach the heart, manifesting itself in Intermittents, Remittents, Dysenteries, &c; hence in hot climates these diseases prevail extensively.-(Amer. Jour. Med. Science, Jan. 1849.)

This theory of the origin of Autumnal diseases is supported by a vast array of facts presented by different authors; from all of which it may indeed be clearly seen that the common causes of disease, by arresting the functions of the skin, and deranging those of the liver and lungs, participate in some degree and in some way in originating almost every case of every disease. The process by which this is effected is well presented by Dr. Bradley of California, in a communication some time ago received from him. After alluding to the constant change going on in the structure of the body, through the processes of assimilation and depuration, and the importance of the function of perspiration he says:-

“The exhaling vessels of the skin are ordinarily capable of conducting the refuse and effete materials of the body to its surface amend presenting them to the atmosphere: and under the stimulus of other great warmth or physical exercise, of actually throwing them on the skin in the form of sweat. But, in the absence of such stimuli, another auxiliary is required: viz. an atmosphere having an affinity for the exhaled matters. In a healthy condition of the atmosphere such affinity is an active, positive force of great power. But this healthy state of the atmosphere does not always exist. Its absorbing power may be diminished by several causes;

1. By the evaporation of simple water in such quantity that the temperature of the air in warm weather and the dewpoint are brought to a near approximation.

2. By an excess of carbonic acid gas in the air. While vegetation is growing luxuriantly, carbon in large quantities is abstracted from the atmosphere, assimilated in the formation of liquin and the basic structure of woods and plants; and the atmosphere is purified by the loss of carbon. But, later in the season, when plants decline in their growth, the atmosphere becomes surcharged with carbonic acid; and by thus becoming satiated with those materials of which the waste and refuse exuvia from the human lungs and skin are composed, its affinity for those carboniferous exhalations is greatly weakened.”

Now I can readily accept all of these propositions as true, But I still feel confident that all these external physical influences, after acknowledging their importance to the fullest extent, are only the exciting causes which stir up and modify the action of Malaria in constitutions already saturated with it. These exciting causes of disease are in operation in a high degree every where, and yet we never see a clear case of pure “every other day, shaking ague” produced by any of them, though they originate almost every other disease that any of us have ever seen. Some writers acknowledge that they have met with cases of ague that originated they know not where or how; as Dr. Wood says, (Practice, Vol. 1., p. 239,) he has seen some cases “that could by no possibility be traced to Malaria” If the author was searching for stagnant pools of evaporating water in which might be seen great quantities of vegetable material in a state of chemical decomposition, he may have failed to discover it He may also have seen large masses of such material in an active state of putrefaction, like the rotting cabbages in London, mentioned by Dr. Watson, (Practice, p. 454,) and seen no ague produced by it; for it is not in the formation of deleterious gases by chemical decomposition that Malarious diseases originate, In what then does Malaria or Ague Miasm consist, and what is its nature and character?

Of the precise nature of this agent it may not be possible to speak with positive certainty. “It is” says Dr. Drake, “known only by its effects on the living organism,” but, “relying on its effects to guide us in our estimate of its character, we may say that the efficient cause of Intermittent Fever is a peculiar poison of a sedative and irritating quality, somewhat like the narcotico-irritating gases, or certain solid and fluid bodies which in large doses, suddenly destroy life by reducing the powers, and in smaller portions weaken while they pervert the functions.”-(Drake, Diseases of the Mississippi Valley.)

On reviewing all the facts collected by my own observations continued through many years in a malarious country, and carefully examined the different theories yet proposed by Medical Philosophers, I have been convinced that the only one capable of explaining the phenomena I have witnessed, is that which I wish now to present in the smallest space that will permit me to render it intelligible.

Malarious diseases are generally, perhaps always excited by some of the ordinary disturbing causes that originate other diseases: but these causes never produce real Intermittents or Ague in persons who are not already infected or poisoned by breathing, or otherwise receiving the specific poison that is the common cause of that peculiar disease. That poison, though of vegetable origin, is not the result of ordinary vegetable decomposition: it is not formed by chemical action disorganizing the dead plants and forming their constituents into new chemical compounds: for Malarious diseases every where occur most frequently at the season of the year in which chemical decomposition of plants has scarcely begun. Ague occurs, not at the time of the year when plants are undergoing any chemical decomposition, but at that time in the Summer when ordinary vegetation has completed “its period of active growth, and its vital powers are exhausted,” and when another race of less perfect plants spring forth from the dying and dead vegetables, grow upon them and feed on the substance, “the exhausted debris and the various exuvia of plants, weeds and grasses” Having waited for their food to the latest season of heat, they spread and reproduce themselves with astonishing rapidity. Of these parasitic, or fungous plants some are too small to be visible to human sight, and others grow rapidly to a great size, feeding always on old and decomposing organic substances in a state of decay or incipient putrefaction.

It is believed that universal observation will show that, although the chemical decomposition of all animal and vegetable products may give rise to disease of some kind; still it is not Intermittent fever that is thus produced. It is only seen when the more perfect plants become the prey of others more minute, analogous in their character to those imperfectly organized fungi which start up by millions over every surface of decaying vegetation in the warmth, moisture and darkness of a hot Summer evening. That they are all poisonous need not here be proved at length, the fact is generally admitted; but its importance is only beginning to be appreciated. I have now only room to present a few considerations which may indicate the direction in which the true theory of Malaria and its effects may be sought for.

“The insolubrity of a place,” says Dr. Mitchell of Philadelphia, “has the most constant relation to the habits of the living vegetation. Whatever be the temperature or humidity the most unhealthy period of the year is, in any given locality that when the more perfect plants have completed their annual task of growth, flowering and fruitage, and feel the weakness of an exhausting effort,” and when the mysterious fungi, “as if to triumph over a worn out foe, come forth to plunder and destroy it.” (On the origin of Malarious Fevers.)

The cause of Ague, whatever it be, is most active during the hours of darkness; and it is then only that the infinitesimal organic fungi grow with a rapidity that surpasses the powers of propagation of all plants known to science. As the minutest mushrooms spring up and grow to maturity in a single night, absorbing into their own structure all the hydrogen and nitrogen that can be extracted from the dead but partially decomposed matter on which they live; they throw off into the air the surplus carbonic acid not needed in the completion of their own watery organization. The conditions most favorable for the development of the infinitesimal fungi that originate Ague, are found in the “rich damp air of a swamp.” Each growing sporule or vesicle that rises to float in the evening mist is invested, says Heasinger, “with a polarizing membrane, and consequently, possesses electrical relations to the polarized vesicles” of the fog that surrounds it, “being imbued with moisture, with exhalations from the earth and screened by the shadows of night.”

It has often been remarked that the poison that originates Intermittent fever may remain for many hours or even days in a dormant or inactive state after it has been received into the system in large quantities. This mysterious feature in its character is considered to be only explicable on the supposition that the marsh poison. “is organic and vital, and that the phenomena of the disease depend on its modification and reaction in the body.” It can therefore “remain dormant like some of the animal poisons; and its absorbed germs may be stimulated, not only by time, but season, according to laws little as yet understood,” and “there is no known poison but the fungi, whose action is so uniformly and irregularly postponed.”-(Mitchell, Causes of Malarious and Epidemic diseases, Phila. 1847, and 1859.)

The cell spores of the fungi, being more or less electrical, may sometimes be arrested in their progress by a low wall, or a screen of trees; they can in this way produce Agues in certain places very near to others where the disease is never seen. They may occur on one side of a street and not on the other; may encroach on new territory in a hot season succeeding a wet one: the spores may be wafted in some cases to great distances, passing near to healthy places. Being susceptible of reproduction and progressive growth, the cell germs may originate Ague in any place that furnishes the proper soil for their growth, and when this is not found, the place is healthy, though very near the most poisonous places. For the reproduction of the spores the marsh mist is an important element, though not the only one. They may be developed amid the filth, the rubbish and decaying material found in an old building, or in grassy lawns surrounding it; in the damp sheets of beds standing long unused: and in old books and papers. They may be borne by the evening wind from marshes in the suburbs into every apartment and dwelling of a city; and, yet produce Ague only in places that furnish the proper material for the cell germs to grow in. Consisting of Organized bodies, possessing electrical qualities, and enshrouded in the moisture of the mist they may be arrested by the most trifling defence, as by a gauze veil or screen drawn across the window in the vicinity of the most unhealthy places; and their poisonous powers may be destroyed by artificially drying and heating the air in the apartment. We know of no poison but the infinitesimal fungi that is thus disarmed of its power by heat.

Here it is necessary to draw a clear line of distinction between that peculiar vegetable product called Malaria and all others which never produce any of its peculiar effects. It may in general terms be asserted that Ague is never caused by any of the gases formed in the chemical decomposition of any vegetable; nor by the drinking of water containing any of the known aquatic plants that are large enough to be within the visible and tangible field of Botanical research. Of all plants known to Botany not one is capable of directly causing Ague, except in the manner pointed out by Hahnemann. We have just seen the effect of the fresh water Algae, Conferva and numerous other aquatic plants tested on a grand scale by the eight hundred thousand inhabitants of this city, who have been using Croton water fully saturated with them for many weeks: and yet it cannot be said that Ague has been sensibly increased by it. What then are the conditions necessary to transform the minute vegetables of the Croton river into the pestilent Malaria? Spread it abroad over a large surface of the ground, let it stand long enough to be called “dead water,” let the heat of August dry it up into the air, leaving all its vegetable material spread upon the earth's surface. During the progress of evaporation, all the organic matter will be invaded by that new, more mysterious sub-vegetable fungus, which will find in this dead material its favorite soil and food. The infinitesimal spores of which it consists, though transcending in their minuteness all the powers of your Microscopes are as much a real organic existence as the matter of Small pox, or Syphilitic contagion; though they are less able to reproduce themselves under all circumstances. This is the enemy that rose from the drying sands of the Guadiana in Spain. Though invisible to the eyes of Wellington and his Medical Counsellors, it possessed a dynamic power which neither the arms nor the science of Britain could overcome.

The nature of the Malaria that produces Yellow fever is still an enigma among Medical Philosophers. The opinion is gaining ground that the specific cause of this disease consists in minute fungous sporules. Mr. Hassell says, (Lancet Feb. 12,1853,) that the matter of “black vomit” examined by him with the microscope, consisted of a vast number of irregular, brown colored bodies, resembling blood discs shrivelled and discolored, but insoluble in Acetic acid. From this insolubility he infered that they could not be blood discs, and that they must be sporules of a Microscopic fungus, and that they might be important agents in keeping up the vomiting.

The connection between Yellow fever and Intermittents will, we think, be found to consist in their being each produced by a specific Malaria consisting of an infinitesimal fungus entirely distinct from that which causes the others, though in many respects they obey similar laws.

On no other theory yet proposed can we explain the introduction of Yellow fever by means of trunks and unwashed clothing from infected places into new localities where it never appeared before. It has been repeatedly proved that Yellow fever is a non-contagious disease: but it is equally well established that it can be introduced: that it may be carried in trunks or clothing, in the filth and animal impurities which in darkness and dampness furnish the most favorable place for the growth of the cell spores. When thus carried to a Northern city, they encounter the usual difficulties of tropical plants attempting to establish themselves where the soil and climate may not be the most favorable. They may grow in New York though transplanted from Havana or Vera Cruz; but if they do grow it must be under the most favorable conditions; the soil, temperature &c., on which the prosperity of the whole tribe of fungi depend, must be favorable. The germs when once ashore, may slowly migrate toward the land, and even by chance be wafted to other neighboring spots where they may grow and create new foci of disease. As in such places Yellow fever is an exotic it cannot flourish as successfully as in its native climate; and it is always destroyed by the first frost. We thus see how it is that Yellow fever though not contagious, can be imported: that it spreads but little in Northern villages: that it may become Epidemic in cities in which great impurities are permitted to accumulate: that in the warmer cities of the South it may originate from the cell spores of the preceding season which the mild winter had not entirely destroyed. We see how a crew, perfectly healthy, may bring with them in the closed hold of their ship the germs of disease, which may afterwards infect those who unload the ship. These first cases may, after a few days be followed by other cases of disease in the vicinity, originating from the new crop of cell spores grown upon the land.

We pass over many of the features of Yellow Fever which on any other theory would be inexplicable, but which become entirely intelligible if the theory we have adopted be the true one. We omit, for want of room, the application of this theory to the explanation of the anomalous phenomena presented by Asiatic cholera. We might trace it from its point of departure from the Delta of the Ganges in India to Bokhara and Samarcand; to Teheran and to the Caucasian Mountains, to the shores of the Black Sea: thence counter marching to Bagdad, and advancing again northward into Russia. We might follow it in its invasion, in winter, of the frozen steppes of Tartary; and then marching over Northern Europe to Britain, crossing the Atlantic to Canada, ascending the St. Lawrence, following the lakes and great rivers to every city and most of the villages of the Mississippi Valley. We should everywhere see that in “its progress along streams, its preference for the damp parts of cities, and its domestication in India, its anomalies and inconsistencies can all be accounted for on the supposition that “its producing cause consists of invisible organic spores, capable of being conveyed in the atmosphere, reproducing themselves where the proper soil is found in which they can grow, and dying out when this appropriate soil is not found.-(Mitchell, p. 137.)

There are still many forms, yet unnoticed, in which Malaria rises from the earth. As one among them, presenting the acme and climax of what Malaria can do, we may select Cretinism in the valleys of the Alps. A few years ago when Dr. Johnson travelled through Switzerland and Italy, to observe the influence of change of air on health, the centre of Cretinism was Sion in the Valais. With mountains rising 4000 feet on each side and shutting out the light of the sun, this village presented in most of its streets “a nameless mass of vegeto-animal corruption which under a tropical sun would be the seat of pestilence and death.” “Goitre on such a scale,” says Johnson, “as we see it in this valley is bad enough; but Cretinism is a cure for the pride of man, and may here be studied on the largest scale and in its most frightful colors. This dreadful infirmity of body and mind,” which was first described on this very spot 200 years ago, still reigns in the valleys of the Alps, a standing and perpetual curse, blighting the present and the future of thousands of families through successive generations. From common Goitre to Cretinism, from a state bordering on health, down to complete destitution of intelligence, and to an existence purely vegetative, the disease presents an infinite variety.

The physical aspect of the Cretin is melancholy. “He is not more than four or five feet in height, often much less.

The head is deformed in shape, too large for the body: skin yellow, cadaverous, or of a mahogany color, wrinkled or of an unearthly pallor, with unsightly eruptions: the flesh is soft; tongue large, often hanging out of the mouth: eyelids thick, eyes red, prominent, watery, squinting; countenance idiotic; nose flat; mouth large, gaping, with saliva flowing from it; lower jaw elongated; abdomen pendulous, limbs crooked, short, distorted, and permitting only a waddling progression; external senses often imperfect, many being deaf and dumb. The whole appearance is that of premature old age. The moral picture is still more humiliating. The intellectual functions are suspended and the lower animal passions are increased in activity. To eat and sleep are their chief pleasures. After eating they bask in the sun, insensible alike to every stimulus that agitates the minds of savage or civilized man.”

The cause of Cretinism is a physical, not a moral one. It is bounded by certain altitudes above the level of the sea. The valleys and ravines of the mountains are its chief seats. “At the height of 500 or 600 fathoms on the mountains Cretinism and Goitre disappear, and within a few years sanitary reform has greatly diminished them in Sion, and other places in the Alpine Valleys. Among the moral causes known to promote them, authors mention the indolence of the inhabitants, their want of education, the filth of their houses, the badness of their food, intemperance, and their many low vices.” (Johnson on change of Air.)

I must now leave, without naming them, a vast number of Malarious diseases that equally deserve our notice. We have at least seen enough of the character and nature of Malaria to be satisfied that it is an evil of such magnitude, that had Pandora's box contained nothing else, the goddess would have left behind her on earth a penalty sufficiently heavy to punish the whole race for the impiety of Prometheus.