This cow (No. 551) was tested with tuberculin in a dairy herd about four months before her picture was taken, and was found to be affected with tuberculosis. Microscopic examinations show that she is passing tubercle bacilli with her fæces. She is entirely too fat to be regarded as a good dairy cow, and shows no symptoms of disease or distress. A fairly large number among tuberculous cows of equally fine appearance examined post-mortem at the experiment station have been found to be affected with advanced and more or less generalized tuberculosis.

FIG. 7.-Cow No. 551, too fat for dairy purposes, and appearing to be perfectly healthy; found recently in a herd supplying milk to Washington; tubercle bacilli found in fæces. (Schroeder, Circular 118, Bureau of Animal Industry, United States Department of Agriculture.)

PERCENTAGE OF DANGEROUS Cows IN DAIRY HERDS.

We now come to the fourth question, which concerns the percentage of cows in dairy herds that are dangerously tuberculous among those found to be affected with tuberculosis through the application of the tuberculin test. It must be borne in mind constantly that the term dangerously tuberculous" is used only for the sake of convenience, to designate those cows of which it can be shown beyond doubt that they are disseminating tubercle bacilli, not actually to separate the dangerously from the not dangerously tuberculous, which is impossible.

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The number of cows examined to obtain an answer to the fourth question was not large; there were 24 which were removed directly from dairy herds, and 6 others which were known to have been affected with

tuberculosis three years or more. Among the former, 10, or a trifle over 40 per cent., were found to be expelling tubercle bacilli, and among the latter all were expelling them. Examinations of the same kind will be continued, and a report will probably be published later, when the results in a larger number of cases can be given.

The cows removed from dairy herds, notwithstanding their tuberculous condition, had the general appearance of ordinary dairy cows; and those regarding which it could be demonstrated that they were expelling tubercle bacilli appeared to be and acted fully as well as those regarding which this could not be demonstrated. Among the 24 cows, 12 were specially selected for another investigation, because a careful physical inspection indicated that they were in the early stages of the disease. From this we may conclude that the examination of a larger number of tuberculous dairy cows will tend to increase rather than reduce the percentage of those which are without doubt expelling tubercle bacilli; though it must be admitted that the physical inspection of tuberculous cows gives no reliable or satisfactory information about their condition, unless they are so badly diseased that no conscientious dairyman would continue to sell their milk.

From the 6 cows known to have been affected with tuberculosis for three years or longer, all of which were passing tubercle bacilli in a manner capable of actual proof, we may justly conclude that with possibly rare exceptions all tuberculous cows eventually become dangerous; and it is merely a question of time after a cow has contracted tuberculosis when she will begin to scatter tubercle bacilli. The prevalence of tuberculosis among dairy cows has been estimated at all the way from 10 per cent. to 90 per cent. The one figure is certainly too low and the other too high. There are many herds that have never been tuberculous, some that have been cleaned of tuberculosis, and others in which every cow is affected. The best evidence we have of the common presence of tuberculosis among dairy cows is the claim made by some dairymen that a milk famine would result from the condemnation of all tuberculous cows for dairy purposes. The dairymen who make this claim evidently know what they are talking about; and, though we may assume that they make it rather with the intention to oppose a feared general application of the tuberculin test to dairy herds than to call attention to an extremely dangerous and objectionable condition, the claim is in truth a strong argument to prove how urgently vigorous action is needed to clean dairy herds of diseased animals.

DANGER FROM INFECTED MILK AND BUTTER.

We must now return to the significance of a sediment in milk. We have seen from the work of the United States Public Health and MarineHospital Service that among 172 samples of city milk examined, 121, or 70 per cent., contained a sediment after standing a few hours in the original containers, and that the sediment consisted in part of cow faces. Tuberculosis is so common among dairy cattle that milk producers frequently assert, as before stated, that a milk famine would be one of the results if the tuberculin test were applied to all dairy cattle, and if all those reacting were condemned for dairy purposes. We know that it can be definitely shown that about 40 per cent. of all cows that react to the tuberculin test, though they still retain the appearance of health, are actively passing tubercle bacilli; we know that the commonest mode for tubercle bacilli to be expelled from the body of a tuberculous cow is with. her fæces; and we know that it has been demonstrated that the bacilli contained in the fæces of tuberculous cows are alive and virulent. Add to this the two facts that butter made from milk soiled with the fæces of cow No. 1 produced tuberculosis on the inoculation of guinea pigs, and that the tuberculous infection contained in the butter made from the milk of cow No. 509 showed no diminution of virulence after forty-nine days, and it is hardly necessary to formulate the conclusion that tuberculosis. among dairy cows is one of the greatest dangers to which public health is exposed, and that every effort should be made by those who have the welfare of humanity at heart to correct this great evil.

Doctors Herr and Beninde,1 two German investigators, concluded from their work that skim milk, buttermilk, cream, butter and centrifuge slime or sediment obtained from infected milk contained tubercle bacilli, and that the most intensely infected of these substances are butter and centrifuge slime. Among 444 samples of butter tested by them and other investigators, 60, or over 13 per cent., were found to contain tubercle bacilli. Broërs 2 of Utrecht places the frequency with which the milk of his country contains tubercle bacilli at 10 per cent., and shows that they may be present in skim milk, cream, buttermilk and butter, and retain their virulence a long time. Brittlebank of England reports that the milk supplied to the city of Manchester, obtained from different counties, showed from 3 per cent. to 12 per cent. of the samples examined to be infected with tubercle bacilli. Dr. Albin Burkhardt,4 after the examination of 1,452 human cadavers, found that 91 per cent.

1 Zeitschrift für Hygiene, etc., Vol. 38, p. 180.

2 Zeitschrift für Tuberkulose, etc., Vol. X., No. 3.

3 Experiment Station Record, Department of Agriculture, Vol. XVIII., p. 581.

4 Zeitschrift für Hygiene, etc., Vol. 53, No. 1.

showed lesions of tuberculosis, irrespective of the cause of death; Nägeli, from the examination of 500 cadavers, places the figure at 96 per cent.; and Schlenker, from 100, makes it 66 per cent. Other investigators have added the weight of their testimony to substantiate this amazing frequency with which persons are shown to be affected with. tuberculosis. These autopsy revelations indicate that few human beings entirely escape tuberculosis, though the majority die of other diseases, and many are not conscious during their lives that they are affected. This is just what we should expect when we know that tubercle bacilli, concealed in butter, milk, cream and other dairy products, are systematically and regularly distributed in a way that insures their ingestion by persons wherever the sale of milk from tuberculous cows is permitted. If the public were thoroughly informed of the dangers- among which tuberculosis is only one of many to which it is exposed through the use of impure, dirty and infected milk, the demand for milk of approved purity would rise to the magnitude of a concerted national movement, and would sweep all objections and difficulties out of its way. Inform a man that a single one among many loaves of bread - you do not know which is contaminated with arsenic, strychnin or some other commonly dreaded poison, and he will go very hungry before he risks eating any loaf of the lot. He knows what arsenic and strychnin are, and what he must expect from their introduction into his stomach. Yet he continues to use milk and dairy products, and permits his family to use them, without first testing their purity or insisting that the doubt about their purity shall be removed, notwithstanding that they have repeatedly been shown to contain poisons fully as objectionable and potent as those above named, such as the germs of tuberculosis, typhoid fever, scarlet fever, diphtheria and other diseases, and the poisons that are the cause for the high death rate from abdominal diseases among children who have not passed the milk-drinking period of life.

THE GREAT IMPORTANCE OF A PURE MILK SUPPLY.

There is an important moral side to the milk question which must not be ignored. We may have the right — a very doubtful right, to be exact — to neglect the dangers to which we, as adults capable of judging and acting for ourselves, are exposed; but we have absolutely no right to neglect the conditions that cause suffering and death among children. The failure to act and to act quickly and unceasingly until a safe milk for children, at least, is within easy reach of every mother, may be characterized as barbarous, if not criminal, indifference. It is an offence against the innocent, unquestioning confidence which children repose in their adult friends.

Under our present conditions of civilization the importance of milk is second only to that of air and water. Without milk thousands of children who grow to useful maturity would starve before they completed the first year of their lives. The excellent work done by Dr. George W. Goler of Rochester, N. Y., proved beyond doubt that thousands of lives are annually lost through the use of impure milk. The reform his praiseworthy and untiring energy brought about in Rochester, by no means a very large city, reduced the mortality among children under five years from 7,451 for the ten years ending in 1896 to 4,965 for the ten years ending in 1906. This shows a saving of 2,486 lives, among which 1,554, or 62.5 per cent., were children under one year old, — that is, had not passed the period of life during which milk forms the most important element of their daily food.

What can be done by substituting a pure milk supply for an impure one is shown by the following quotation from the New York Medical Record's London letter of July 26, 1907:1

At Leeds a voluntary society established a year ago a depot for supplying a pure milk, as the corporation had no power to do so. But the health officer has made a report on the working. He concludes that, making allowance for the mortality for the first week of life and for those born moribund, there has been a saving of life of 25 per cent. among the children using the society's milk, as compared with those living in the same district at the same ages and during the same seasons fed otherwise. The experiment was on a small scale, but as far as it went was more successful than he could have anticipated.

The dairyman is not alone to blame for impure milk. As a rule, he attempts to supply a pure milk to his customers, and is not conscious of the impurities and infections in the article he is distributing. The price he receives is too low for the production of a constantly pure milk. He should be better paid. If the money that now goes to druggists, doctors, undertakers and burial grounds directly through the use of impure and unwholesome milk could be diverted to the dairyman, he would be amply paid for producing a wholesome, safe milk, and the entire community would profit by having better health, fewer deaths and less suffering.

CONCLUSIONS.

1. The dangerously tuberculous cow is an animal that may long retain the appearance and general semblance of perfect health.

2. The methods we now have to detect the presence of tubercle bacilli in the secretions and discharges from tuberculous cows are too crude

1 New York Medical Record, Aug. 17, 1907, p. 275.