At the present time the fact of the infectiousness of consumption is firmly established in a scientific way, and enough is known of the natural history of the infective agent, the bacillus of tuberculosis, and of the ways in which it is communicated to man, to enable us to lay down rules with more positiveness than hitherto for the prevention of the disease.

The source of infection is twofold: from tuberculous animals to man, and from one human being to another. The tuberculosis of animals and human consumption are of the same nature.

From domestic animals there is danger of contracting the disease by the use of flesh, and especially by the use of milk from those which are tuberculous. Many children die in their earlier years from various tubercular diseases, tubercular inflammation of the brain, consumption of the bowels," etc., and it is now assumed with much probability that the great majority of these die from infection received in the milk from tuberculous cows, or in that from mothers suffering from tuberculosis in some form.

By far the greatest source of infection, however, is consumptive human beings, but fortunately the ways in which the contagion is disseminated are but few, and by intelligent care they may be effectually controlled.

Practically, from the human source, we may consider the expectoration (the sputum) as the only serious danger. The consumptive sputum usually contains an abundance of the infection, the bacilli, and these microscopic organisms are found to be capable of retaining their vitality and their infectious qualities for a long while, even after the sputum has been thoroughly dried.

It has long been known that tuberculosis may be communicated to animals experimentally by feeding them with tuberculous matter, by injecting it into their tissues, or by causing them to breathe air into which tuberculous sputum had been atomized. More recently, since the discovery of the bacillus tuberculosis, it has been found that the bacilli may be cultivated upon artificial media, and that when thus cultivated and freed from all other matter which might possibly be infective, tuberculosis may still be communicated to animals in the ways which have been mentioned above, and with great certainty.

Experiments, the conclusions from which can hardly be questioned, have shown that the breath of the consumptive patient is

not infectious, and that the same may be said of the sputum so long as it remains moist.

Another line of investigation has proved that the careless consumptive patient is a focus of infection, and a danger to all persons who come much in proximity to him, especially to those who dwell in the same rooms with him.

The reason of this is that the expectoration of the patient, spit upon floors, carpets, pocket handkerchiefs or clothing, becomes dried and pulverized and, floated in the air, still contains the infectious germs, and cannot be inhaled without great danger.

Though infection may be regarded as the principal, the essential cause of consumption, there are nevertheless various untoward influences which have much to do with increasing the death-rate from this disease, and should never be disregarded. The most important of these are the breathing of impure air, particularly that of unventilated sleeping rooms and living rooms, the use of food not sufficiently nutritious, and dwelling upon a soil that is damp.

How far heredity is a cause of consumption, is, from the nature of the question, hard to determine. Since the infectiousness of the disease has been shown, many family groups of consumption, "house epidemics," may fairly be assumed to be from infection rather than from hereditary influence. Some able writers would discard heredity as one of the causes of tuberculous disease, but others, more conservative in their views, while believing that direct inheritance is rare, think that certain peculiarities of constitution, favoring susceptibility, are transmissible from parent to child.

RESUME.-1. Tuberculosis is an infectious disease. 2. The breath of the consumptive patient is not infectious.

3. The sputum is harmless as long as it remains moist. 4. Tuberculous infection is produced, in the great majority of cases, by the inhalation of dried and pulverized tuberculous sputum.

PREVENTION.

The restriction of infection.

It should be impressed upon consumptive patients and other persons living with them, that the sputum (what they cough up) is dangerous and must be properly disposed of.

The sputum should be received in a spit-cup or spittoon containing a little water or disinfecting fluid, and must never be spit upon floors, carpets, or received in handkerchiefs. If a disinfecting solution is used, corrosive sublimate is unsuitable, chloride of lime is efficient but irritates the air passages, carbolic acid (Solution E.) with 5 per cent. of tartaric acid or hydrochloric acid, will be the best disinfectant generally available.

If occasionally it is necessary to have handkerchiefs or cloths soiled with the sputum they should be boiled as soon as possible, and before drying.

The spittoon should be of such shape that the sputum may easily fall into the water without soiling the sides of the vessel. For patients not able to sit up, a small spit-cup with a handle should be used. When flies are present, it should be covered.

Spit-cups and spittoons should be emptied and cleansed often with boiling water and potash soap. When the house has a drainage system, the contents may be poured down the water-closet or slup-hopper; when it has not, they should be buried in ground which will not be turned up soon.

The sputum should not be thrown out upon the surface of the ground near inhabited places, nor on manure heaps, nor where animals may get it, nor where it may soil animal food.

Boxes filled with sand or sawdust should not be used. Cheap wooden and pasteboard spit-cups are now on the market, one of which may be burned daily or oftener with its contents as a convenient way of disposing of the sputa.

A pocket spit flask of small size has been devised, which may be used while away from home.

The floors, wood-work and furniture of room3 in which consumptive patients stay, should be wiped with a damp cloth, not dusted in the usual way.

The patient's clothing should be kept by itself and thoroughly boiled at the washing.

The patient should be made to understand that in neglecting these measures, he is imperiling his friends, and at the same time diminishing very much his own chances of recovery by re-infecting himself with the inhalation of his own dried and pulverized sputum.

After a death from this disease has occurred, the patient's room, clothing, and bed should be disinfected. For this purpose, boil all bed and personal clothing, or disinfect them when practicable in a

steam disinfector; wash furniture, wood-work, walls, and floors with carbolic acid solution (Solution E), and thoroughly expose the rooms to light and air.

If raw milk is used as food, especially if it is to be given to ch ldren, an assurance should be had that the cows which produce it are perfectly healthy and subjected to healthful treatment.

When there is any doubt as to the health of the cows which furnish the supply, the milk should be boiled before use.

Thorough cooking will remove all danger of tuberculosis through the medium of the meat supply.

Tuberculous mothers and those inclined to consumption should, under no conditions, nurse their babies.

To guard against contracting the disease.

By observing the rules which are expressed and suggested in the foregoing, the principal, if not all, danger of infection may be avoided.

Whatever has a tendency to undermine the general health increases the susceptibility to the infection and diminishes the power of recovery from incipient tuberculosis.

A fact abundantly shown in the dissecting room is, that many persons dying of other diseases, have had tuberculosis and have recovered in its early stages.

This tendency to recover is greatly strengthened by the habitual breathing of pure air. Means should be provided for the abundant ventilation of inhabited rooms, particularly of sleeping rooms, school-rooms, and churches.

The open air treatment of consumptives and those who are threatened with tuberculous disease, has given much better results than any other. Particularly in Germany, and to some extent in this country, such treatment has been systematized in "sanitaria" for consumptives. Here the patients have the advantage of a regular life, nutritious food and such exercise as they can bear without fatigue; but the chief curative agent is an abundance of fresh air. Even in the coldest of winter weather, patients, after a period of gradual habituation, and always guided by the judgment of the physician, pass the whole day walking in the open air, or sitting or lying on resting places wrapped comfortably in blankets. Usually no claim is made for advantages of climate. An abundance of pure air is the all important thing.

DISINFECTANTS.

For convenience of reference this list of disinfectants is re-printed in this connection.

SOLUTION A.-For excreta, privy vault, woodwork and other surfaces.

SOLUTION B.For excreta, privy vaults.

SOLUTION C.-For clothing, the hands, excreta, vaults, furniture, and woodwork.

SOLUTION D.-For the person, the hands.

SOLUTION E.-For clothing, the hands, the person, excreta.

BOILING. For clothing. - SULPHUR FUMIGATION. For use only where liquid disinfectants cannot be used or to supplement other methods.

Choloride of Lime,
Water,

SOLUTION A.

6 ounces.

1 gallon.

Mix. Cost about three cents, or seventy-five cents a barrel. (Decolorizes and destroys fabrics.)

SOLUTION B. "Purple Solution.”

Corrosive Sublimate,

Permanganate of Potash,
Water,

2 drachms.

2 drachms.

1 gallon.

Mix and dissolve. Label, Poison! Cost, two or three cents a gallon, when the chemicals are bought by the pound. (Stains fabrics, etc.)

The permanganate of potassium in this solution is used to give it color as a precaution against mistakes. It also, in this quantity, increases the deodorizing qualities of the solution. This is approximately a 1:500 solution of the sublimate; therefore, mixed with an equal quantity of water or liquids to be disinfected, it gives us a 1:1000 mixture. One ounce of this solution contains very nearly one grain of the corrosive sublimate.

This is sixteen times stronger than Solution B, and is intended as a standard solution from which, by dilution with water, a solution of the proper strength for use may be made. To make from it a solution of the proportion of

1:500, add 8 oz3. to 1 gallon of water.
1:1000, add 4 ozs. to 1 gallon of water.

1:2000, add 2 ozs. to 1 gallon of water.