Part 3

This we know; all beyond this is conjecture, but as to the most probable of these conjectures, some who have thought on this subject believe that the preponderance of evidence justifies the conclusion that the predisposing causes may themselves become efficient causes; that instances in which they actually do so, are constantly passing before our eyes; that it is practicable to manufacture fever and even epidemic fever to any amount by placing a population under certain known conditions; that it is practicable to prevent the outbreak of epidemics altogether by placing the population under certain other conditions;[10] that the prevalence of the predisposing causes in particular localities, in certain intensities, is sufficient to produce local epidemic outbreaks; that the prevalence of such causes in such intensities, joined to some general conditions of the atmosphere, such as the meteorological conditions which have been enumerated, particularly those which favour the accumulation and concentration of the products of organic decomposition, are all that is required to engender wide-spread epidemics. Those who adopt this view contend that the existence of a primary cause as a distinct and separate entity is not necessary to account for the phenomena.

The more common opinion however is, that joined to the predisposing causes there must always be present a primary cause, having a distinct existence, capable of travelling from one part of the globe to another; capable of spreading over any space however extended, or of confining itself to any space however small—a district, a street, a house, a room.

Footnote 10:

See Baltimore case, p. 78.

It is urged that though we are unacquainted with the physical form or chemical properties of this body, this is no reason why we should not understand its force as a special agent in the production of disease, just as we know the forces of other physical bodies, though not their nature.

The existence of such a body being assumed, it is conceived that it exists not in a gaseous but in a liquid state. It is supposed that it cannot exist in a gaseous state because a gas is readily diffused and dissipated; because when organic matter is reduced to a gaseous state, it has passed from the organic into the inorganic kingdom, and there is no evidence that the elementary bodies belonging to this kingdom are capable of producing any form of fever; and because there is indubitable evidence that organic matter in a recent state of putrescence—the more recent the more potent—is capable of producing the most deadly forms of fever. From these considerations it is conjectured that the primary cause, whatever it be, is some subtle fluid which has not wholly lost its organic composition, and that it consists of particles of extreme minuteness, capable of attaching itself to the surfaces of other bodies, and even of increasing under favourable circumstances.

It is further thought that this body is not equally diffused through the atmosphere, but is only partially distributed, and that this accounts for the local distribution of epidemics, and for their occasional absence from places which apparently present all the conditions favourable to their development.

Lastly, the opinion is gaining ground, that this body acts in the manner of a ferment. It is urged in favour of this view, that a ferment being an azotized substance in a state of putrefactive alteration, the body in question must find, in the decomposing organic compounds with which impure blood is charged, precisely the materials for taking on the fermenting process. The advocates for this view think that the term “_zymotic_” is not only the appropriate name of the whole of this class of diseases, but that it also declares an interesting fact connected with them. Whatever may be the truth with respect to these points, on which at present we have no positive knowledge, one thing is certain, that practically our concern is with the known causes,—the ascertained conditions. These are palpable, definite, and capable of complete removal and prevention.

Overcrowding, for example, we can prevent; the accumulation of filth in towns and houses we can prevent; the supply of light, air, and water, together with the several other appliances included in the all-comprehensive word CLEANLINESS, we can secure. To the extent to which it is in our power to do this, it is in our power to prevent epidemics.

The human family have now lived together in communities more than six thousand years, yet they have not learnt to make their habitations clean. At last we are beginning to learn the lesson. When we shall have mastered it, we shall have conquered epidemics. Our duties, then, and our hopes in this respect, I shall proceed to show.

* * * * *

The principal constituents of the atmosphere maintain their equilibrium steadily over the whole surface of the globe. There is scarcely any difference in the relative proportion of its oxygen and nitrogen in the torrid zone and in the arctic regions. Whatever influence the atmosphere may have on climate must consequently depend on something adventitious to it and not in anything forming a part of it. Possibly therefore that something may be, in some degree, under human control.

The main constituents of climate are temperature and moisture, and these are the climatic conditions that exercise the greatest influence on epidemics.

Minor but still important conditions are the nature of the soil, the proportion of land that is cleared and under cultivation, the extent of forests, lakes, and rivers, the prevailing winds, the electrical state of the atmosphere, and so on.

The temperature is highest where the sun’s rays are vertical, or nearly so; where the sky is cloudless; where the day is longest; and where there is the smallest difference between the fervid noon-tide heat and the temperature of the short night.

The moisture is greatest where in addition to all the other sources of humidity there are periodical rains. In the countries subject to these rains, the entire extent of the level and low land is often covered a foot deeper with water than before the rain set in.

Elevated temperature and excessive moisture are combined in tropical countries; and they are concentrated in those parts of the tropics in which there are extensive forests having an undergrowth of luxuriant vegetation; in which the tides of the ocean penetrate deeply into the interior of the land, and mix with the waters of the rivers; and in which the rivers constantly overflow their banks and form marshes and swamps.

In tropical countries there are tracts such as these that extend in unbroken continuity hundreds of leagues. The western coast of Africa (the Bight of Benin) presents an unbroken area of upwards of 100,000 square miles, consisting of one vast alluvial and densely-wooded forest, irrigated by Atlantic tides, and intersected by numerous rivers and creeks, whose muddy banks are constantly overflowed.

In describing a tropical forest, Humboldt says, “Under the bushy, deep, green verdure of trees of stupendous height and size, there reigns constantly a kind of half daylight, a sort of obscurity, of which our forests of pines, oaks, and beech trees afford no example; forming a carpet of verdure, the dark tint of which augments the splendour of the aërial light.”

With this luxuriance of vegetation is combined a corresponding abundance of animal life. The earth and air teem with living creatures.

“The mould,” observes the same distinguished traveller, “contains the spoils of innumerable quantities of reptiles, worms, and insects. Wherever the soil is turned up we are struck with a mass of organic substances, which by turns are developed, transformed, and decomposed. Nature in these climates appear more active, more fruitful, we might say more prodigal of life.”

The air is still more alive than the land. Insects fill the lower strata of the atmosphere to the height of fifteen or twenty feet, like a condensed vapour. It is estimated that a cubic foot of air is often peopled by a million of winged insects, which contain a caustic and venomous liquid, several species being nearly two lines (1.8) long.

When two persons who have their home in these regions meet in the morning, the first questions they address to each other are, “How did you find the zancudoes during the night?” “How are we to-day for the mosquitoes?” An ancient form of Chinese politeness, showing the ancient state of that country, was—“Have you been incommoded in the night by serpents?”

It appears that there are still inhabited places in which the Chinese compliment on the serpents might be added to that of the mosquitoes.

Proportionate to this prodigality of organic life is the amount of organic decomposition, the products of which are poured into the atmosphere and suspended in the surrounding vapour and fog,[11] to which they give a decided and often a highly offensive odour.

Footnote 11:

See note, p. 16.

“On fixing our eyes on the tops of the trees,” describes Humboldt, “we discovered streams of vapour wherever a solar ray penetrated and traversed the dense atmosphere, exhaling, together with the aromatic odour yielded by the flowers, the fruit, and even the wood, that peculiar odour which we perceive in autumn in foggy seasons. It might be said, that notwithstanding the elevated temperature the air cannot dissolve the quantity of water exhaled from the surface of the soil and of the vegetation.”

“At the distance of several miles from the coast,” says Dr Daniell, in describing the western shores of Africa, “the peculiar odour arising from swampy exhalations and the decomposition of vegetable matter is very perceptible, and sometimes even offensive. The water also is frequently of a dusky hue, with leaves, branches, and other vegetable debris floating on the surface, brought down from the interior by innumerable narrow channels that empty their turbid streams into the open ocean.”

It is under these climatic conditions that the worst forms of epidemics are engendered: the most sudden in their attack, the most rapid in their development, the most general in their prevalence, and the most mortal.

The form of the epidemic prevalent in any particular district is dependent on the physical characters of the immediate neighbourhood. Thus intermittents prevail chiefly in marshy and swampy districts: remittents also chiefly there, though not exclusively; while in other localities other forms arise approximating to the continued type of temperate climates.

For the most part these epidemics are strictly endemic, and are confined to the particular regions in which they are engendered. They never pass the limit of the equatorial or tropical zone. Yellow Fever, one of the most common and destructive of these diseases, is still more restricted in its range, being confined within a definite line determined by temperature. It is incapable of existing where the average range of the thermometer is greater than from 76° to 86° of Fahrenheit, or where the temperature varies more than from 5° to 10° night and day. Extreme heat and moderate cold immediately stop it; nay, even the prevalence of a cold wind for a few hours only.

In other instances these epidemics pass beyond the regions in which they are produced, and sometimes extend to all the other quarters of the globe. The Black Death, the range of which we have seen, was engendered in China; the Cholera of our own day, generated in the delta of the Ganges, the great source and centre of Indian epidemics, ravaged that country long before it directed its course to Europe.

When these tropical epidemics advance into more temperate climes, they lay aside nothing of their nature; they lose but little of their power. Wherever they go they decimate the populations which they attack.

One remarkable peculiarity of some of these epidemics is, that natives of the region in which they prevail are for the most part unsusceptible to them. This is true however only of particular forms of pestilence. Some of them acknowledge no acclimation. Cholera, for example, attacks equally natives and new comers. On the other hand, yellow fever rarely attacks the natives who reside permanently within its zone. Its chief victims are strangers who have recently arrived within its sphere, particularly the inhabitants of northern climates. The susceptibility to its influence appears to be strictly proportionate to the degree of northern latitude from which the stranger has arrived, and the shortness of the interval that has passed since he left the European for the Equatorial regions.

We see something of the same kind in the wide-spread epidemics of our own country. During the prevalence of Cholera it was observed over and over again, that persons coming directly from the pure air of the country into the infected part of a town, were seized with the disease. The explanation is not obvious. It would seem, however, to be connected with the suddenness of the shock on the system. Priestley found, that after shutting up a mouse in a given quantity of air a considerable time, it seemed to be weak, and to be slowly dying. If at this period he put a fresh mouse into the same air, it instantly died. It seems as if the system can bear a pestiferous atmosphere better when gradually than when suddenly exposed to it.

I do not know that I can give a more vivid picture of a tropical epidemic than that which is afforded by the outbreak of Cholera in the 86th regiment at Kurrachee in June, 1846.

On this occasion the atmosphere was very peculiar,—damp, hot, stagnant, and oppressive. Not a breath of air was stirring. A few isolated cases of cholera had occurred for some days. The utmost alarm was excited in the minds of experienced persons, who felt certain that an epidemic was at hand. Their fears were too fully realized. On the night of the 15th, upwards of 40 men were seized with cholera in its severest form; in two days more 256 were attacked, of whom 131 were already dead.

“The floors of the hospital,” says Dr Thom, the surgeon of the regiment, “were literally strewed with the livid bodies of men labouring under the pangs of premature dissolution. Many were brought in with the cold and clammy damp of death; as if sudden obstruction of every vital function had taken place, and the fountains of life had been arrested by an invisible but instantaneous shock. It was indeed a sight never to be forgotten, to behold the powerful frames of the finest men of a fine corps, who had that morning been in apparent good health, and most of them on the evening parade, as if at once stricken down, and striving, with the last efforts of gigantic strength, to resist a death-call that would not be refused.”

In describing a river on the west coast of Africa, Dr Daniell says—“When I visited it, I found two vessels moored a short distance from its mouth, one of which within the space of five months had buried two entire crews, a solitary person alone surviving. The other, which had arrived at a much later period, had been similarly deprived of one-half of its men, and the remainder were in such a debilitated condition as to be incapable of undertaking any active or laborious duty. Immediately before, another vessel had sailed from this port in such a deplorable state as to be solely dependent on the aid of Kroomen to perform the voyage.”

In the statistical report of Sir Alexander Tulloch it is stated, that out of 1658 white troops sent out to military stations on the western coast of Africa, 1271 perished from climatic diseases; while of the 387 who remained to be sent home, 17 died on their passage; 157 were reported as incapable of further service; and 180 as qualified only for garrison service; thus leaving only 33 out of 1658 men who were fit for active service.

As we pass out of the torrid zone a remarkable change takes place in the general character of epidemics. They lose more and more of their intermittent type, and become either remittent or continued. The remittent keeps its hold over the southern part of Europe, and continually breaks out in the form of Yellow Fever. As we proceed northward out of the yellow fever zone, that disease wholly disappears, and typhus and its kindred maladies take its place; typhus commencing precisely at the point where yellow fever ends.

There is, indeed, one of the ordinary diseases of temperate climes, and only one, which appears capable of penetrating within the torrid zone, and of committing greater ravages there than in lower temperatures, and that is Small-pox. With this exception, the ordinary epidemics of temperate climates do not enter the tropics, while, on the other hand, the ordinary epidemics of the tropics every now and then decimate the temperate regions.

“In these our latitudes,” says Dr William Fergusson, “cold and fatigue, and sorrow and hunger, will generate fever anywhere; but every region, every climate, will exhibit its own form of fever. With us it is Typhus; in the warmer countries of Europe, Remittent; in the upper Mediterranean, Plague; in the Antilles and Western Africa, Yellow Fever; this last being restricted to particular localities, temperatures, and elevation. While typhus fever goes out when you enter the tropics, it is there that yellow fever commences; the pure epidemic of a hot climate that cannot be transported or communicated upon any other ground. Places, not persons, constitute the rule of its existence. Places, not persons, comprehend the whole history, the etiology of the disease. Places, not persons! Let the emphatic words be dinned into the ears of the Lords of the Treasury, of Trade and Plantations, until they acquire the force of a creed, which will save them hereafter from the absurdity of enforcing a quarantine[12] in England against an amount of solar heat of which its climate is insusceptible. Let them further be repeated in the Schools of Medicine until the Professors become ashamed of imbuing the minds of the young with prejudice and false belief, which, should they ever visit warmer climates, may cause them to be eminently mischievous in vexing the commerce and deeply and injuriously agitating the public mind of whatever community may have received them.”

Footnote 12:

See Cases of the Eclair, Dygden, &c., _post._

Climate differs not only in different countries but in different parts of the same country. The climate of the country is different from that of the city. The climate of every city, town, and village, differs from that of every other. The temperature, the moisture, and the other meteorological conditions of different districts, nay, even of different streets in the same town, vary to such a degree as to influence materially their relative salubrity and the prevalence or absence of particular classes of disease. These local climatic conditions and their connection with prevalent diseases, have not as yet received due attention: when they shall have received it—and they will receive it—a new light will be shed on local epidemics.

* * * * *

I pass now to CIVILIZATION.

We have no sufficient knowledge of the state of the people and of their diseases, in any of the civilized nations of antiquity, to trace the relation between them. The authentic history of periods, comparatively near to our own time, as far as concerns the diseases of the people, goes scarcely further back than the 14th century. The first great epidemic, to which I have so often called attention, occurred in that century, and we have reliable evidence, both of the phenomena attending this plague and the condition of the people at that time. I assume this period therefore as my starting-point.

I take a civilized community to be one in which there exist—

1. A sovereign authority.

2. Laws incorruptibly administered.

3. Physical comfort generally diffused.

4. Intellectual development and activity generally diffused.

5. Recognition of the fundamental principles of religion and morality.

Without the two first, there can be no security for life and property, both of which must be placed in absolute and unquestionable safety before a single step can be taken out of the lowest depth of barbarism. Without the two last, none of the others can be acquired. These conditions are therefore the basis of the pyramid of society.

Taking these then as the essential constituents of civilization, and applying them as a test to Great Britain, we shall see that at the commencement of the 14th century England was in a state of barbarism, since every one of these elements was wanting, although the foundation of political and social institutions containing the germs of liberty and progress had been already laid.

Practically, however, at that period there was no sovereign authority, for the king had no sufficient power to maintain order, to protect the rights and liberties of the people, or to defend his own throne against armed men nominally his subjects; while the lord of every feudal castle exercised a more perfect sovereignty over his vassals than the so-called monarch over the nation.

Every town was a fortress, and every house in which it was safe to dwell a castle, the inmates of which, like people in a garrison, constantly held themselves prepared to resist attack, from which they were never secure. They slept with arms at their side.

Marauders openly encamped on the public roads for the plunder of the wayfarer, which often ended in his murder. Few persons ventured to travel alone, and none without the reasonable apprehension that they might never return alive.

Scarcely a third part of the area of the kingdom was under cultivation. The remainder consisted of moor, forest, and fen. Vast tracts were under water during the greater part of the year, and at other times formed morasses, marshes, and swamps.

Immediately beyond the walls that encompassed the towns were large stagnant ditches, which being the nearest receptacles for refuse, were full of all sorts of decomposing filth.

The streets were narrow, unpaved, undrained, uncleansed, and unlighted. There was no provision for the removal of the town refuse. Gutters were formed at the sides of the streets, as in Bethnal Green and the neglected parts of all our towns at the present time, into which the inhabitants threw the refuse of their houses; forming in dry weather a semi-fluid mass of corrupting animal and vegetable matter, and in rainy weather black turbid rivulets which ultimately poured their contents into some water-course.

The houses were mean and squalid, built of wood and wattles, thatched with straw, without chimneys, the windows without glass, the floors without boards, the furniture of the rudest description; the use of linen was scarcely known; common straw formed the king’s bed. “The floors,” says Erasmus, writing two centuries later, “generally are made of nothing but loam, and are strewed with rushes, which being constantly put on fresh, without a removal of the old, remain lying there, in some cases for twenty years; with fish bones, broken victuals, the dregs of tankards, and impregnated with other filth underneath, from dogs and men.” Contemporary writers concur in representing the offensive odour of decaying straw and rushes as universal in the houses.

There was no knowledge of the art of collecting, preserving, and storing fodder. The animals for winter food were slaughtered in autumn, and their flesh salted or smoked. It was only during three months of the year, from Midsummer to Michaelmas, that any fresh animal food, excepting game and river fish, was tasted even by the nobles of the land. The common people subsisted chiefly on salted beef, veal, and pork, the price of which was one-half less than that of wheat in the time of Henry VIII.