Granted that mosquitoes do cause and are the only cause of malaria, what are you going to do about it? At first sight any campaign against malaria which involves the extermination of the mosquito would appear about as hopeless as Mrs. Partington"s attempt to sweep back the rising Atlantic tide with her broom. But a little further investigation showed that it is not only within the limits of possibility, but perfectly feasible, to exterminate malaria absolutely from the mosquito end. In the first place, it was quickly found that by a most merciful squeamishness on the part of the plasmodium, it could live only in the juices of one particular genus of mosquito, the _Anopheles_; and as nowhere, not even in the most benighted regions of Jersey, has this genus been found to form more than about four or five per cent of the total mosquito population, this cuts down our problem to one-twentieth of its apparent original dimensions at once. The ordinary mosquito of commerce (known as _Culex_) is any number of different kinds of a nuisance, but she does not carry malaria.
Here the trails of the extermination party fork, one of them taking the perfectly obvious but rather troublesome direction of protecting houses and particularly bedrooms with suitable screens and keeping the inhabitants safely behind them from about an hour before sundown on. By this simple method alone, parties of explorers, of campers, of railroad-builders going through swamps, of the laborers on our Panama Ca.n.a.l, have been enabled to live for weeks and months in the most malarious regions with perfect impunity, so long as these precautions were strictly observed. The first experiment of this sort was carried out by Bignami upon a group of laborers in the famous, or rather infamous, Roman Campagna, whose deadly malarial fevers have a cla.s.sic reputation, and has achieved its latest triumphs in the superb success of Colonel Gorgas at Panama. While this procedure should never be neglected, it is obvious that it involves a good deal of irksome confinement and interferes with freedom of movement, and it will probably be carried out completely only under military or official discipline, or in tropical regions where the risks are so great that its observance is literally a matter of life or death.
The other division of malaria-hunters pursued the trail of the _Anopheles_ to her lair. There they discovered facts which give us practically the whip-hand over malarial and other tropical fevers whenever we choose to exercise it. It had long been known that the breeding-place of mosquitoes was in water; that their eggs when deposited in water floated upon the surface like tiny boats, usually glued together into a raft; that they then turned into larvae, of which the well-known "wigglers" in the water-b.u.t.t or the rain-barrel are familiar examples; and that they finally hatched into the complete insect and rose into the air.
Obviously, there were two points at which the destroyers might strike, the egg and the larvae. It was first found that, while the eggs required no air for their development, the larvae wiggled up to the surface and inhaled it through curious little tubes developed for this purpose, oddly enough from their tail-ends. If some kind of film could be spread over the surface of the water, through which the larvae could not obtain air, they would suffocate. The well-known property of oil in "sc.u.mming over" water was recalled, two or three stagnant pools were treated with it, and to the delight of the experimenters, not a single larva was able to develop under the circ.u.mstances. Here was insecticide number one. The cheapest of oils, crude petroleum, if applied to the pool or marsh in which mosquitoes breed, will almost completely exterminate them. Scores of regions and areas to-day, which were once almost uninhabitable on account of the plague of mosquitoes, are now nearly completely free from these pests by this simple means. An ounce to each fifteen square feet of water-surface is all that is required, though the oiling needs to be repeated carefully several times during the season.
But what of the eggs? They require no air, and it was found impossible to poison them without simply saturating the water with powerful poisons; but an unexpected ally was at our hand. It was early noted that mosquitoes would not breed freely in open rivers or in large ponds or lakes, but why this should be the case was a puzzle. One day an enthusiastic mosquito-student brought home a number of eggs of different species, which he had collected from the neighboring marshes, and put them into his laboratory aquarium for the sake of watching them develop and identifying their species. The next morning, when he went to look at them, they had totally disappeared. Thinking that perhaps the laboratory cat had taken them, and overlooking a most contented twinkle in the corner of the eyes of the minnows that inhabited the aquarium, he went out and collected another series. This time the minnows were ready for him, and before his astonished eyes promptly pounced on the raft of eggs and swallowed them whole. Here was the answer at once: mosquitoes would not develop freely where fish had free access; and this fact is our second most important weapon in the crusade for their extermination. If the pond be large enough, all that is necessary is simply to stock it with any of the local fish, minnows, killies, perch, dace, ba.s.s,--and presto! the mosquitoes practically disappear. If it be near some larger lake or river containing fish, then a channel connecting the two, to allow of its stocking, is all that is required.
On the Hackensack marshes to-day trenches are cut to let the water out of the tidal pools; while in low-lying areas, which cannot be thus drained, the central lowest spot is selected, a barrel is sunk at this spot, and four or five "killie" fish are placed in it. Trenches are cut converging into this barrel from the whole of the area to be drained, and behold, no more mosquitoes can breed in that area, and, in the language of the day, "get away with it."
Finally, most consoling of all, it was discovered that, while the ordinary _Culex_ mosquito can breed, going through all the stages from the egg to the complete insect, in about fourteen days, so that any puddle which will remain wet for that length of time, or even such exceedingly temporary collections of water as the rain caught in a tomato-can, in an old rubber boot, in broken crockery, etc., will serve her for a breeding-place, the _Anopheles_ on the other hand takes nearly three months for the completion of her development. So that, while a region might be simply swarming with ordinary mosquitoes, it would frequently be found that the only places which fulfilled all the requirements for breeding-homes for the _Anopheles_, that is, isolation from running water or larger streams, absence of fish, and persistence for at least three months continuously, would not exceed five or six to the square mile. Drain, fill up, or kerosene these puddles,--for they are often little more than that,--and you put a stop to the malarial infection of that particular region. Incredible as it may seem, places in such a hotbed of fevers as the west coast of Africa, which have been thoroughly investigated, drained, and cleaned up by mosquito-brigades, have actually been freed from further attacks of fever by draining and filling not to exceed twenty or thirty of these breeding-pools.
In short, science is prepared to say to the community: "I have done my part in the problem of malaria. It is for you to do the rest." There is literally no neighborhood in the temperate zone, and exceedingly few in the tropics, which cannot, by intelligent cooperation and a moderate expense, be absolutely rid first of malaria, and second of all mosquito-pests. It is only a question of intelligence, cooperation, and money. The range of flight of the ordinary mosquito is seldom over two or three hundred yards, save when blown by the wind, and more commonly not more than as many feet, and thorough investigation of the ground within the radius of a quarter of a mile of your house will practically disclose all the danger you have to apprehend from mosquitoes. It is a good thing to begin with your own back yard, including the water-b.u.t.t, any puddles or open cesspools or cisterns, and any ornamental water gardens or lily-ponds. These latter should be stocked with fish or slightly oiled occasionally. If there be any acc.u.mulations of water, like rain-barrels or cisterns, which cannot be abolished, they should either be kept closely covered or well screened with mosquito netting.
It might be remarked incidentally in pa.s.sing, that the only really dangerous s.e.x in mosquitodom, as elsewhere, is the female. The male mosquito, if he were taxed with transmitting malaria, would have a chance to reecho Adam"s cowardly evasion in the Garden of Eden, "It was the woman that thou gavest me." Both s.e.xes of mosquitoes under ordinary conditions are vegetable feeders, living upon the juices of plants. But when the female has thrown upon her the tremendous task of ripening and preparing her eggs for deposition, she requires a meal of blood--which may be a comfort to our vegetarian friends, or it may not. Either she requires a meal of blood to nerve her up to her criminal deed, or, when she has some real work to do, she has to have some real food.
The mosquito-brigade have still another method of checking the spread of malaria, at first sight almost a whimsical one,--no less than screening the patient. The mosquito, of course, criminal as she is, does not hatch the parasites _de novo_ in her own body, but simply sucks them up in a meal of blood from some previous victim. Hence by careful screening of every known case of malaria, mosquitoes are prevented from becoming infected and transmitting the disease. Instead of the screens protecting the victims from the mosquitoes, they protect the mosquitoes against the victim.
This explains why hunters, trappers, and Indians may range a region for years, without once suffering from malaria, while as soon as settlers begin to come in in considerable numbers, it becomes highly malarious.
It had to be infected by the coming of a case of the disease.
The notorious prevalence of malaria on the frontier is due to the introduction of the plasmodium into a region swarming with mosquitoes, where there are few window-screens or two-story houses.
No known race has any real immunity against malaria. The negro and other colored races, it is true, are far less susceptible; but this we now know applies only to adults, as the studies of Koch in Africa showed that a large percentage of negro children had the plasmodium in their blood. No small percentage of them die of malaria, but those who recover acquire a certain degree of immunity. Possibly they may be able to acquire this immunity more easily and with less fatality than the white race, but this is the extent of their superiority in this regard. The negro races probably represent the survivors of primitive men, who were too unenterprising to get away from the tropics, and have had to adjust themselves as best they might.
The serious injury wrought in the body by malaria is a household word, and a matter of painfully familiar experience. Scarcely an organ in the body escapes damage, though this may not be discovered till long after the "fever-and-ague" has been recovered from.
As the parasite breeds in the red cells of the blood, naturally its first effect is to destroy huge numbers of these, producing the typical malarial _anaemia_, or bloodlessness. Instead of 5,000,000 to the cubic centimetre of blood the red cells may be reduced to 2,000,000 or even 1,500,000. The breaking down of these red cells throws their pigment or coloring-matter afloat in the blood; and soaking through all the tissues of the body, this turns a greenish-yellow and gives the well-known sallow skin and yellowish whites of the eyes of swamp-dwellers and "river-rats."
The broken-down sc.r.a.ps of the red blood-cells, together with the toxins of the parasite, are carried to the liver and spleen to be burned up or purified in such quant.i.ties that both become congested and diseased, causing the familiar "biliousness," so characteristic of malaria.
The spleen often becomes so enormously enlarged that it can be readily felt with the hand in the left side below the ribs, so that it is not only relied upon as a sign of malaria in doubtful cases, but has even received the popular name of the "ague-cake" in malarious districts.
So full is the blood of the parasites, that they may actually choke up the tiny blood-vessels and capillaries in various organs, so as to block the circulation and cause serious and even fatal congestions.
Obstructions of this sort may occur in the brain, the liver, the coats of the stomach, or intestines, and the kidneys; and they are the chief cause of the deadly "congestive chills," or pernicious malarial paroxysms, which we have alluded to.
The kidneys are particularly liable to be attacked in this way; indeed, one of their involvements is so serious and fatal in the tropics as to have been given a separate name, "Blackwater fever," from the quant.i.ties of broken-down blood which appear in and blacken the urine.
The vast majority of attacks of malaria are completely recovered from, like any other infection, but it can easily be seen what an injurious effect upon the system may be produced by successive attacks, keeping the entire body saturated with the poison; while there is serious risk of the parasite sooner or later finding some weak spot in the body,--kidney, liver, nervous system,--where its incessant battering works permanent damage.
How long the infection may lurk in the body is uncertain; certainly for months, and possibly for years. Many cases are on record which had typical chills and fever, with abundance of plasmodia in the blood, years after leaving the tropics or other malarious districts; but there is often the possibility of a recent re-infection.
Altogether, malaria is a remarkably bad citizen in any community, and its stamping-out is well worth all it costs.
CHAPTER XIV
RHEUMATISM: WHAT IT IS, AND PARTICULARLY WHAT IT ISN"T
What"s in a name? All the aches and pains that came out of Pandora"s box, if the name happens to be rheumatism. It is a term of wondrous elasticity. It will cover every imaginable twinge in any and every region of the body--and explain none of them. It is a name that means just nothing, and yet it is in every man"s vocabulary, from proudest prince to dullest peasant. Its derivative meaning is little short of an absurdity in its inappropriateness, from the Greek _reuma_ (a flowing), hence, a cold or catarrh. It is still preserved for us in the familiar "salt rheum" (eczema) and "rheum of the eyes" of our rural districts.
But this very indefiniteness, absurdity if you will, is a comfort both to the sufferer and to the physician. Moreover, incidentally, to paraphrase Portia"s famous plea,--
It blesseth him that _has_ and him that _treats_; "T is mightier than the mightiest.
It doth _fit_ the throned monarch _closer_ than his crown.
To the patient it is a satisfying diagnosis and satisfactory explanation in one; to the doctor, a great saving of brain-f.a.g. When we call a disease rheumatism, we know what to give for it--even if we don"t know what it is. As the old German distich runs,--
Was man kann nicht erkennen, Muss er Rheumatismus nennen.[2]
[Footnote 2: What one cannot recognize he must call rheumatism.]
However, in spite of the confusion produced by this wholesale and indiscriminate application of the term to a host of widely different, painful conditions, many of which have little else in common save that they hurt and can be covered by this charitable name-blanket, a few definite facts are crystallizing here and there out of the chaos. The first is, that out of this swarm of different conditions there can be isolated one large and important central group which has the characters of a well-defined and constant disease-ent.i.ty. This is the disease known popularly as rheumatic fever, and technically as acute rheumatism or acute articular rheumatism. In fact, the commonest division is to separate the "rheumatisms" into two great groups: acute, covering the "fever" form, and chronic, containing all the others. From a purely scientific point of view, this cla.s.sification has rather an undesirable degree of resemblance to General Grant"s famous division of all music into two tunes: one of which was Old Hundred, and the other wasn"t. But for practical purposes it has certain merits and may pa.s.s.
Every one has seen, or known, or had, the acute articular form of rheumatism, and when once seen there is no difficulty in recognizing it again. It is one of the most striking and most abominable of disease-pictures, beginning with high fever and headache, then tenderness, quickly increasing to extreme sensitiveness in one or more of the larger joints, followed by drenching sweats of penetrating acid odor. The joint attacked becomes red, swollen, and glossy, so tender that merely pointing a finger at it will send a twinge of agony through the entire body, and the patient lies rigid and cramped for fear of the agony caused by the slightest movement. The tongue becomes coated and foul, the blood-cells are rapidly broken down, and the victim becomes ashy pale. He is worn out with pain and fever, yet afraid to fall asleep for fear of unconsciously moving the inflamed joint and waking in tortures; and altogether is about as acutely uncomfortable and completely miserable as any human being can well be made in so short a time.
Fortunately, as with its twin brother, the grip, the bark of rheumatism is far worse than its bite; and a striking feature of the disease is its low fatality, especially when contrasted with the fury of its onslaught and the profoundness of the prostration which it produces. Though it will torture its victim almost to the limits of his endurance for days and even weeks at a stretch, it seldom kills directly. Its chief danger lies in the legacies which it bequeaths. Though, like nearly all fevers, it is self-limited, tends to run its course and subside when the body has manufactured an ant.i.toxin in sufficient amounts, it is unique in another respect, and that is in the extraordinary variability of the length of its "course." This may range anywhere from ten days to as many weeks, the "average expectation of life" being about six weeks. The agonizing intensity of the pain and acute edge of the discomfort usually subside in from five to fifteen days, especially under competent care.
When the temperature falls, the drenching sweats cease, the joints become less exquisitely painful, and the patient gradually begins to pull himself together and to feel as if life were once more worth living. He is not yet out of the woods, however, for while the pain is subsiding in the joints which have been first attacked, another joint may suddenly flare up within ten or twelve hours, and the whole distressing process be repeated, though usually on a somewhat milder and shorter scale. This uncertainty as to how many joints in the body may be attacked, is, in fact, one of the chief elements in making the duration of the disease so irregular and incalculable.
Even when the frank and open progress of the disease through the joints of the body has come to an end, the enemy is still lying in wait and reserving his most deadly a.s.sault. Distressing and crippling as are the effects of rheumatism upon the joints and tendons, its most deadly and permanent damage is wrought upon the heart. Fortunately, this vital organ is not attacked in more than about half the cases of acute rheumatism, and in probably not more than one-third of these are the changes produced either serious or permanent, especially if the case be carefully watched and managed. But it is not too much to say that, of all cases of serious or "organic" heart disease, rheumatism is probably responsible for from fifty to seventy per cent. The same germ or toxin which produces the striking inflammatory changes in the joints may be carried in the blood to the heart, and there attack either the lining and valves of the heart (endocardium), which is commonest, or the covering of the heart (pericardium), or the heart-muscle. So intense is the inflammation, that parts of the valves may be literally eaten away by ulceration, and when these ulcers heal with formation of scar-tissue as everywhere else in the body, the flaps of the valves may be either tied together or pulled out of shape, so that they can no longer properly close the openings of the heart-pump. This condition, or some modification of it, is what we usually mean when we speak of "heart disease," or "organic heart disease." The effect upon the heart-pump is similar to that which would be produced by cutting or twisting the valve in the "bucket" of a pump or in a bulb syringe.
In severe cases of rheumatism the heart may be attacked within the first few days of the disease, but usually it is not involved until after the trouble in the joints has begun to subside; and no patient should be considered safe from this danger until at least six weeks have elapsed from the beginning of the fever. The few cases (not to exceed one or two per cent) of rheumatic fever which go rapidly on to a fatal termination, usually die from this inflammation of the heart, technically known as endocarditis. The best way of preventing this serious complication and of keeping it within moderate limits, if it occurs, is absolute rest in bed, until the danger period is completely pa.s.sed.
Now comes another redeeming feature of this troublesome disease, and that is the comparatively small permanent effects which it produces upon the joints in the way of crippling, or even stiffening. To gaze upon a rheumatic knee-joint, for instance, in the height of the attack,--swollen to the size of a hornet"s nest, hot, red, throbbing with agony, and looking as if it were on the point of bursting,--one would almost despair of saving the joint, and the best one would feel ent.i.tled to expect would be a roughening of its surfaces and a permanent stiffening of its movements.
On the contrary, when once the fury of the attack has pa.s.sed its climax, especially if another joint should become involved, the whole picture changes as if by magic. The pain fades away to one-fifth of its former intensity within twenty-four, or even within twelve hours; three-fourths of the swelling follows suit in forty-eight hours; and within three or four days" time the patient is moving the joint with comparative ease and comfort. After he gets up at the end of his six weeks, the knee, though still weak and stiff and sore, within a few weeks" time "limbers up" completely, and usually becomes practically as good as ever. In short, the violence and swiftness of the onset are only matched by the rapidity and completeness of the retreat. It would probably be safe to say that not more than one joint in fifty, attacked by rheumatism, is left in any way permanently the worse.
But, alas! to counterbalance this mercifulness in the matter of permanent damage, unlike most other infections, one attack of rheumatic fever, so far from protecting against another, renders both the individual and the joint more liable to other attacks. The historic motto of the British in the War of 1812 might be paraphrased into, "Once rheumatic, always rheumatic." The disease appears to be lost to all sense of decency and reason; and to such unprincipled lengths may it go, that I have actually known one luckless individual who had the unenviable record of seventeen separate and successive attacks of rheumatic fever. As he expressed it, he had "had rheumatism every spring but two for nineteen years past." Yet only one ankle-joint was appreciably the worse for this terrific experience.
Obviously, the picture of acute rheumatism carries upon its face a strong suggestion of its real nature and causation. The high temperature, the headache, the sweats, the fierce attack and rapid decline, the self-limited course, the tendency to spread from one joint to another, from the joints to the heart, from the heart to the lungs and the kidneys, all stamp it unmistakably as an infection, a fever. On the other hand, there are two rather important elements lacking in the infection-picture: one, that, although it does at times occur in epidemics, it is very seldom transmitted to others; the other, that one attack does not produce immunity or protect against another. The majority of experts are now practically agreed that _acute_ rheumatism, or _rheumatic fever_, is probably due to the invasion of the system by some microorganism or germ. When, however, we come to fixing upon the particular bacillus, or micrococcus, there is a wide divergence of opinion, some six or seven different eminent investigators having each his favorite candidate for the doubtful honor. In fact, it is our inability as yet positively to identify and agree upon the causal germ that makes our knowledge of the entire subject still so regrettably vague, and renders either a definite cla.s.sification or successful treatment so difficult.
The att.i.tude of the most careful and experienced physicians and broad-minded bacteriologists may be roughly summed up in the statement that acute rheumatism is probably due to some germ or germs, but that the question is still open which particular germ is at fault, and even whether the group of symptoms which we call rheumatism may not possibly be produced by a number of different organisms, acting upon a particular type of const.i.tution or susceptibility. There is no difficulty in finding germs of all sorts, princ.i.p.ally micrococci, in the blood, in the tissues about the joints, and on the heart-valves of patients with rheumatism, and these germs, when injected into animals, will not infrequently produce fever and inflammatory changes in the joints, roughly resembling rheumatism. But the difficulty so far has been, first, that these organisms are of several different kinds and distinct species; and second, and even more important, that almost any of the organisms of the common infectious diseases are capable at times of producing inflammation of the joints and tendons. For instance, the third commonest point of attack of the tubercle bacillus, after the lungs and the glands, is the bones and joints, as ill.u.s.trated in the sadly familiar "white-swelling of the knee" and hip-joint disease. All the so-called septic organisms, which produce suppuration and blood-poisoning in wounds and surgery, may, and very frequently do, attack the joints; while nearly all the common infections, such as typhoid, scarlet fever, pneumonia, and even measles, influenza, and tonsillitis, may be followed by severe joint symptoms.
In fact, we are coming to recognize that diseases of the joints, like diseases of the nervous system, are among the frequent results of any and all of the acute infectious diseases or fevers; and we now trace from fifty to seventy-five per cent of both joint troubles and degenerations of the nervous system to this cause. Two-thirds, for instance, of our cases of hip-joint disease and of spinal disease (_caries_) are due to tuberculosis.
The puzzling problem now before pathologists is the sorting out of these innumerable forms of joint inflammations and the splitting off of those which are clearly due to certain specific diseases, from the great, central group of true rheumatism. Most of these joint inflammations which are due to recognized germs, such as the pus-organisms of surgical fevers, tuberculosis, and typhoid, differ from true rheumatism in that they go on to suppuration (formation of "matter") and permanently cripple the joint to a greater or less degree. So that there is probably a germ or group of germs which produces the swift attack and rapid subsidence and other characteristic features of true rheumatism, even though we have not yet succeeded in sorting them out of the swarm. So confident do we feel of this, that although, as will be shown, there are probably other factors involved, such as exposure, housing, occupation, food, and heredity, yet the best thought of the profession is practically agreed that none of these would alone produce the disease, but that they are only accessory causes plus the micrococcus. In practically all our modern textbooks of medicine, rheumatism is included under the head of infections.
This theory of causation, confessedly provisional and imperfect as it is, helps us to harmonize the other known facts about the disease; it has already greatly improved our treatment and given us a foothold for attacking the problem of prevention. For instance, it has long been known that rheumatism was very apt to follow tonsillitis or other forms of sore throat; indeed, many of the earlier authorities put down tonsillitis as one of the great group of "rheumatic" disturbances, and persons of rheumatic family tendency were supposed to have tonsillitis in childhood and rheumatism in later life. Not more than ten or fifteen per cent of all cases gave a history of tonsillitis; but since we have broadened our conception of infection and begun to inquire, not merely for symptoms of tonsillitis, but also for those of influenza, "common colds," measles, whooping-cough, and the like, we reach the most significant result of finding that forty to sixty per cent of our cases of rheumatism have been preceded, anywhere from one to three weeks before, by an attack of some sort of "cold," sore throat, catarrhal fever, cough, bronchitis, or other group of disturbances due to a mild infection. Further, it has long been notorious that when a rheumatic individual "catches cold" it is exceedingly apt to "settle in the joints," and, if these cases happen to come under the eye of a physician, they are recognized as secondary attacks of true rheumatism.
In other words, the "cold" may simply be a second dose of the same germ which caused the primary attack of rheumatism.
This brings us to the widespread article of popular belief that rheumatism is most commonly due to cold, exposure, chill, or damp. Much of this is found on investigation to be due to the well-known historic confusion between "cold," in the sense of exposure to cold air, and "cold," in the sense of a catarrh or influenza, with running at the nose, coughing, sore throat, and fever, a group of symptoms now clearly recognized to be due to an infection. In short, the vast majority of common colds are unmistakably infections, and spread from one victim to another, and this is the type of "cold" which causes the majority of rheumatic attacks.
The chill, which any one who is "coming down" with a cold experiences, and usually refers to a draft or a cold room, is, in nine cases out of ten, the rigor which precedes the fever, and has nothing whatever to do with the external temperature. The large majority of our cases of rheumatism can give no clear or convincing history of exposure to wet, cold, or damp. But popular impression is seldom entirely mistaken, and there can be no question that, given the presence of the infectious germ, a prolonged exposure to cold, and particularly to wet, will often prove to be the last straw which will break down the patient"s power of resistance, and determine an attack of rheumatism.
This climatic influence, however, is probably not responsible for more than fifteen or twenty per cent of all cases, and, popular impression to the contrary notwithstanding, the liability of outdoor workers who are subject to severe exposure, such as lumbermen, fishermen, and sailors, is only slightly greater than that of indoor workers. The highest susceptibility, in fact, not merely to the disease, but also to the development of serious heart involvements, is found among domestic servants, particularly servant girls, agricultural laborers and their families (in districts where wages are low and cottages bad), and slum-dwellers; in fact, those cla.s.ses which are underfed, overworked, badly housed, and crowded together. Diet has exceeding little to do with the disease, and, so far from meat or high living of any sort predisposing to it, it is most common and most serious in precisely those cla.s.ses which get least meat or luxuries of any sort, and are from stern necessity compelled to live upon a diet of cereals, potatoes, cheap fats, and coa.r.s.e vegetables.