§ 1. For all practical purposes, the fevers termed intermittent and remittent may be held to have their origin in one cause. Thus, whether on the marshy coasts of Essex and Kent, or the more dreadful banks of the Gambia and Niger, it is not improbable that the fever so destructive to European life is of one character—mild in Essex; fatal in Sierra Leone. But the fact is not to be overlooked, that when fever assumes an intermittent character, however it may conduce to the inefficiency of the population, it does not greatly swell the bills of mortality; on the other hand, the remittent form of fever constitutes that grand and hitherto insurmountable obstacle which Nature seems to have placed to the extension of the white man over the earth, excluding him, seemingly for ever, from the tropical regions of the world. A favourite theory with medical men was, that the evil influence which causes fever, whether in Essex or on the Gambia, by the Scheld or the Niger, was a certain miasma produced by marshes more or less remote from human abodes; sometimes it was maintained that to produce the miasma these marshes must be in a great measure dried up, or in the process of being so; at other times an opposite opinion was held. These hypotheses were refuted, or at least much shaken, by Major Tulloch, in his invaluable “Statistical Report on the Sickness, Mortality, and Invaliding among Troops on the Western Coast of Africa” (p. 26). “So long as the fever continued to make its appearance during the rainy season, excessive moisture was deemed one of the principal causes, but that theory has been abandoned since it has, on three or four occasions, appeared and raged with equal violence in the middle of the dry season. If we attempt to connect it with temperature, the range of the thermometer offers equally contradictory results, the disease having originated and prevailed nearly as often when that was at the minimum as when at the maximum. Variations in atmospheric pressure afford no clue whatever to the solution of the difficulty, for here, as in all tropical climates, the fluctuations of the barometer are exceedingly slight. No definite connexion has ever been traced between the prevalence of any particular wind and the outbreak of the disease; the breeze blows over the same district in the healthy as in the unhealthy season. Besides, it seems entirely to negative the supposition that any of these can be more, perhaps, than mere accessories, when we find, from 1830 to 1836, the colony of Sierra Leone remarkably free from fever, without any perceptible change in these respects. It does not appear that the composition of the atmosphere during the prevalence of yellow fever in this command has ever been examined, to ascertain if it differed from what has usually been observed at periods comparatively healthy; but this test has been applied without any satisfactory result in other countries. Unless some light, therefore, can be thrown on the subject by a careful examination of the electrical state of the atmosphere at such periods, there seems little hope of the origin of this disease being ever distinctly traced to any appreciable agency—a circumstance which, except as regards the interests of science, is perhaps of less importance, since where the cause is so exceedingly subtle it would, even if discovered, be in all probability beyond human control.”21
In corroboration of the same views, amounting in fact to a rejection of the favourite hypothesis of the professors of the healing art—namely, that this fever originated in the miasma of marshes near the station, this careful and honest observer, whose merits as such have subsequently been fully tested in the celebrated Crimean inquiry, makes this further remark:—“The hypothesis that this fever originates from the miasma of marshes in the immediate vicinity of the station, as elsewhere it has been supposed to do, is directly opposed to the fact of the Isles de Loss, Acera, and the peninsula of Sierra Leone itself, being so subject to it, though all are in a certain degree remote from the operation of any such agency. If it be referred to similar exhalations wafted to the distance of several miles, how is its prevalence to be accounted for at Fernando Po, a mountainous region, and bordering on a mainland still more so, and where, so far as can be ascertained, no such agency is in operation? Instances of disease having raged with the same violence on the rocky Isles de Loss and the sandy wastes of Senegal, as in those parts of the coasts where vegetation is most dense, preclude the likelihood of it originating in a superabundance of that agency. In every description of situation along the coast has this scourge of Europeans been found to prevail. The low, swampy Gambia, the barren Isles de Loss, the beautifully-diversified features of Sierra Leone, the open and park-like territory around Acera, the lone, jungle-covered hills of Cape Coast Castle, and the rugged, mountainous island of Fernando Po, however different in aspect, have all exhibited the same remarkable uniformity in giving birth to the disease.”
It may, indeed, be objected that the fevers of Western Africa differ essentially from those traceable to the deltas of rivers, and to the lowlands alternately inundated and exposed to a high temperature, of more temperate climates; but I see no good reason in favour of such an opinion. The tables of sickness and mortality distinctly state that the fevers were intermittents and remittents, but mainly remittents, and that continued or ardent fever was scarcely present; whilst in Canada precisely the reverse is the case, intermittents prevailing to a great extent, remittents being comparatively rare. It would seem, however, that whether or not these fevers spring from a common cause, the temperature of the locality greatly influences the character of the disease.
It is impossible to deny the influence humidity has in engendering malarious tendencies, but it is not necessary that the humidity be to any great extent. Water is essential to life, it is essential also to the production of fermentation, of putrefaction; the absolute desert, as I have already remarked, is always healthy; so is the surface of the great ocean, which although it abounds with life, never putrefies, never exhales unpleasant odours. Countries, like some districts of Southern Africa and of Australia, where it seldom rains, are the healthiest countries in the world; there fevers of all types are nearly unknown, and the sufferers from such coming from unhealthy climates, recover speedily from the sad condition to which a residence in a tropical country and frequent attacks of fever may have reduced them. The Royal African Regiment, composed mainly of deserters, left the west coast of Africa for the Cape of Good Hope in 1817; many of them were so reduced in health as to be obviously unfit for service in any country where fevers of an intermittent or remittent character prevailed. Now, a residence on the frontiers of the colony of the Cape not only cured these fevers, but seems also to have been equal to the removal of those sequel? of fever and dysentery which haunt those who have greatly suffered from them, bringing them in the end to an untimely grave. Nothing of the kind occurred in this remarkable country; all, or nearly all, recovered, and the mortality and sickness of this shattered corps, removed from Sierra Leone and the Gambia to the frontier districts of the Cape of Good Hope, fell considerably below what it is amongst the same class in Britain. These facts merit the attention of all interested in the welfare of the army of Britain, an army exposed more than any other to the effects of climate in all regions of the world.22
§ 2. The statistics I have just referred to may seem to some to shake all modern theories of malaria that have ever yet been offered to the public. I admit this to be the case; but I trust to be able to show that in the remains of animal and vegetable life, elements collected in the greatest abundance by the banks of rivers and lakes in marshy countries, near shores alternately exposed and covered by the tide, and especially in tidal rivers, but not exclusively in such localities, we have the source of that poison whose terrible effects on human life need not be enumerated here.
The result of Major Tulloch’s report in regard to the relative prevalence at different stations in British America of remittent and intermittent fevers, shows in a still stronger light the difficulty of establishing any uniform connexion between the presence of marshy ground and the existence of these febrile diseases, to which the exhalations from it are supposed to give rise; but they do not refute the view I take,23 which is based on the researches of the profoundest chemists. As it was formerly shown that in some of the Ionian Islands, totally destitute of marsh and comparatively barren of vegetation, more remittent and intermittent fevers have been under treatment among the troops, than in others where these alleged sources of disease existed in the greatest abundance; so in the present Report we find it established, that yellow fever of the most aggravated form has repeatedly made its appearance in Ireland Island in the Bermudas, a rocky barren spot only a few hundred yards in breadth, “containing no marsh, and with little or no vegetation except a few cedar trees.”
“Conversely, again, we find that these diseases prevail to a remarkable extent along the banks of the lakes and the margin of the streams in Upper Canada, while they are comparatively rare in similar situations in the Lower Province; that among the troops at Fredericton, living on the marshy banks of a river, surrounded by a dense vegetation, scarcely a case of them is ever known; and that a similar exemption is enjoyed even by those at Annapolis and Windsor in Nova Scotia, though quartered at the embouchure of rivers daily subject to extensive inundations, and of which the banks, for the distance of several miles, exhibit that combination of mud, marsh, and decayed vegetation which is generally supposed a most prolific source of such diseases.
“When in subsequent reports we come to investigate the operation of these diseases on the west coast of Africa and other colonies, we shall be able to adduce still more satisfactory evidence on this subject; in the meantime we have felt it our duty to place the preceding facts in a prominent point of view, not for the purpose of establishing any particular theory, but to show how inadequate in many instances is the supposed influence of emanations from a marshy soil to account for the origin of these diseases. All the evidence obtained seems only to warrant the inference that a morbific agency of some kind is occasionally present in the atmosphere, which, under certain circumstances, gives rise to fevers of the remittent and intermittent type; and that though the vicinity of marshy and swampy ground appears to favour the development of that agency, it does not necessarily prevail in such localities, nor are they by any means essential either to its existence or operation.
“Notwithstanding the doubt in which this branch of the investigation is still involved, we may venture, from the facts adduced in all the reports hitherto submitted, also to draw the conclusion, that when this morbific agency manifests itself in the epidemic form, its influence is frequently confined to so limited a space as to afford a fair prospect of securing the troops from its ravages by removing to a short distance from the locality where it originated. The history of the epidemic fevers at Gibraltar furnishes several remarkable instances of this kind, and we have also shown that, both in the West Indies and Ionian Islands, one station has frequently suffered to a great extent from yellow fever, while others within the distance of a few miles have been entirely exempt.
“In the epidemic cholera at Montreal and Halifax, which seems to have been in this respect somewhat analogous in its operation, we have also had occasion to remark the sudden cessation of the disease immediately on the removal of the troops to a short distance.”24
The discordance prevailing between observers, equally honest, equally intelligent, arises, no doubt, from this, that all the elements of the problem to be solved are not yet discovered; nor could this be expected until a refined chemistry had more fully developed the relation between chemical and physiological phenomena. The very essence of the affinities between the soil and vegetable and animal life was a complete mystery until lately, whilst the relations of the superambient atmosphere to the organic remains of what had ceased to live, were wholly misunderstood. The cause of the potato blight, which produced a famine in Ireland, is still a mystery; so also is that of the vine. A disease very fatal to horses, called Paard-sick, from its only attacking the horse, is endemic in some districts of the Cape; that is, in the healthiest country in the world. The nature of the Paard-sick has never been discovered. It spares the wilde of the horse genus—the quagga, zebra, &c.—but is fatal to the domestic breed. Man’s interference, then, proves at times fatal to his protegée. It is everywhere the same, unless his interference be guided by all the lights which the highest reasoning powers, the shrewdest observation, and oft-repeated experience can afford. The two Canadas are in an especial manner the land of rivers, lakes, marshy forests, swampy meadows, and a soil into which the plough never penetrated until the white man appeared. As a natural result, it might be conjectured and presumed that intermittents and remittents, under at least certain of their forms, would be equally frequent and universally diffused. Statistics prove it to be directly the reverse, Upper Canada being to Lower Canada, in respect of these fevers, as 178 intermittents is to 26 remittents; whilst even of these 26 it is affirmed that the greater number of them came from the Upper Province. To show that I do not exaggerate this singular fact, I quote the remarkable statistics of Major Tulloch.
“Taking the results of these ten years as the basis of our deductions, then, the prevalence of intermittent fevers in Upper compared with Lower Canada is as 178 to 26. It is necessary, however, to keep in view that all the admissions (amounting only to 26) from intermittent fever in Lower Canada did not originate there, by far the greater proportion of them having occurred among soldiers who came from the Upper Province while labouring under that disease, or who had acquired a predisposition to it during a previous residence there. Indeed, except at Isle aux Naix and the other small stations along the banks of the Richelieu, fevers of the intermittent type are rarely indigenous in Lower Canada; at Quebec they are said to be unknown, and at Montreal nearly so.
“In Upper Canada these diseases prevail most among the troops stationed along the course of the great lakes from Kingston to Amherstberg, they are almost unknown at Penetanguishene and By Town. The settlers who reside even at the distance of a few miles inland rarely suffer from them; yet the districts enjoying this exemption are in many parts covered with lakes, intersected by streams, and abound in marshy ground, decayed vegetation, and all the other agencies to which the origin of this type of fever is generally attributed. A reference to the report on Nova Scotia and New Brunswick will also show that though the same agencies exist to a similar extent at some of the stations in that command, intermittent fevers are almost unknown.
“These diseases, too, are said to be comparatively rare wherever the surface is covered with dense forests, even though the ground is wet and marshy. The vicinity of lands recently cleared is most subject to them, particularly meadows or open patches of the forest, which, though denuded of trees, have not been brought under cultivation. It would appear, too, that their prevalence is diminishing with the progress of agricultural improvement; for it will be observed, on reference to the Abstract of Diseases, No. III. of Appendix, that since 1831—a period during which this province has been rapidly advancing in wealth and population, and many important changes have taken place in the vicinity and stations occupied by the troops—intermittents have become comparatively rare, the proportion attacked having been scarcely one-tenth part so high as the average previous to that period. Intermittents most frequently occur from July to September, when a high temperature prevails; but they are also to be met with, though more rarely, in spring, when that agency could only operate in a trifling degree to induce them. Though a source of inefficiency among the troops, they add but little to the mortality, as not one case in a thousand proves fatal. A person who has been once attacked is exceedingly apt to suffer from them again; but this susceptibility is easily removed by change of residence to the northern parts of the province, or to Lower Canada.
“In some years, fever also manifests itself along the borders of the lakes in the remittent form, but not of so fatal a character as in the West Indies or the Mediterranean; for only one case in sixteen is found to have proved fatal among the troops.
“The febrile diseases of Upper Canada are by no means uniform in their prevalence. Even in years when the degree of temperature, fall of rain, or extent of vegetation have been much the same, the proportion of cases, particularly of intermittents, is very different. A general impression exists, that their prevalence is in some measure dependent on the height of the waters in Lake Ontario, which attain their maximum in June or July. If, from the quantity of snow or moisture in the course of the year, this is found to be greater than usual, febrile diseases are expected to abound, and the reverse if the maximum has been under the average. As Lake Ontario is the reservoir into which all the waters of Upper Canada are drained off before finding their way to the ocean, this theory, if accurately substantiated, would tend to show how far the origin of these diseases depended on moisture, and we therefore instituted the following comparison between the height of the waters in the lake, as measured at Kingston for a series of years, and the prevalence of fever in Upper Canada during the same period:
1818. 1819. 1820. 1821. 1822. 1823. 1824. 1825. 1826. 1827. 1828. Average height of lake
in Kingston Harbour
in each year ft. in.
14 ?9 ft. in.
13 ?3 ft. in.
12 ?3 ft. in.
11 11 ft. in.
12 ?1 ft. in.
13 ?5 ft. in.
13 11 ft. in.
12 ?5 ft. in.
12 10 ft. in.
14 ?3 ft. in.
15 ?7 Cases of intermittent
fever in Upper Canada
110
319
509
348
222
143
171
135
111
220
489
Cases of other fevers
109
?54
150
152
132
?69
168
190
155
185
300
 
“Here we find that, though in the last of these years the maximum height of water in the lake happened to correspond with the greatest prevalence of fever, the latter can by no means be looked upon as a consequence of, or in any way connected with, the former; since in 1818, when the water rose to within a few inches of the same level, there was less fever than in any of the years under observation; whereas in 1820 and 1821, when the waters of the lake appear to have been at the minimum, there was more than in any of the years prior to 1828.
“This supposition seems to have originated in the circumstance of fevers being generally most prevalent from June to October, which happens to correspond with the period when the waters of the lake are at the greatest height; but the wide sphere over which these statistical investigations now extend, has enabled us to show that febrile diseases always prevail most at that season of the year, even in countries where no such cause is in operation to produce them; consequently, the rise of the waters in the lakes can no more be regarded as the cause of fever in America, than the cessation of the trade winds about the same period can be deemed a satisfactory reason for the appearance of that disease in the West Indies. Both are merely coincidences which, by those who have not a sufficiently extensive field of observation, are apt to be mistaken for causes.”
There arises out of all such inquiries one obvious deduction—viz., that the essential nature of malaria is altogether unknown; and that unless we choose to remain contented with such vague hypotheses as those of Macculloch, now adopted by the Medical Board of Health of Great Britain,25 other inquiries must be entered on. The assertion is as easily made as its refutation is difficult, that typhus fever is caused by a neglected drain or ditch; that scarlet fever, small-pox, and cholera have for their origin the same cause; that if they do not immediately produce the poison, they predispose the human frame for its reception; and that as a necessary result, all such diseases, and deaths resulting therefrom, and from zymotic forms of disease generally, are preventible by human agency. Let us leave these Utopian views to the clever pens skilled in the art of making that seem new which is not new, and that seem true which is not true, and patiently inquire into some of the many difficulties besetting all investigations into Nature’s processes, and man’s interpretation of them.