The safest way of disposing of reacting animals, as previously stated, is to slaughter them. In order to reduce the financial loss to a minimum and at the same time guard against the sale of unwholesome meat, it is well to have such animals slaughtered at abattoirs under Federal or other competent veterinary inspection. In this way a large proportion may be safely passed for food and made to yield their full meat value, while only those whose meat may be dangerous to health will be condemned.

In herds where the disease is found it is advisable to repeat the tuberculin test at intervals of six months, and after the disease has apparently been wiped out the test should still be applied once a year until it is known beyond doubt that infection does not remain and has not been reintroduced.

Inspectors should be stationed at important points for the purpose of testing cattle for breeding and dairy purposes, and each State that is endeavoring to eradicate the disease should require that no cattle. for breeding or dairy purposes shall be admitted from without the State unless they have passed the tuberculin test. A good method of preventing the spread of tuberculosis among breeding stock would be the establishment by the State of one or more free herds of breeding cattle for the use of stock raisers in the State, or the State could certify to the health of free herds.

An effective means of locating and eradicating tuberculosis of live stock would be to establish by State legislation a system of tagging cows sent to market from infected districts for slaughter, so that when any are found tuberculous in the meat inspection they may be traced back to the place of origin, thus locating the centers of infection, and steps may then be taken for eradication. The Bureau of Animal Industry is already cooperating with the authorities of some States by reporting on tuberculous animals, and the results so far have been very encouraging. To give the plan general application the authorities should be empowered by law to require that shippers shall tag their cows in such a way that they may be identified and their origin determined.

As the eradication of tuberculosis is largely a public-health measure, it is only reasonable that the State should compensate, at least in part, the persons whose cattle are slaughtered. This is not only fair, but it is absolutely essential if the cooperation of the cattle owners is to be secured.

It will be seen from the methods above discussed that in carrying on work for the eradication of animal tuberculosis in the United States hearty cooperation and concurrence of action between the Federal and State governments will be essential. Under the Constitution the power of the Federal Government in such matters is limited to those aspects which concern interstate commerce, and if a State fails

to do its part the Federal Government can not step in and carry on the work. What the Federal Government can do in such a case, however, is to quarantine the State, or a portion of it, and thus prevent the movement of animals from such a State; but while this action would protect other States, it would not help the situation within the State.

BENEFITS OF ERADICATION.

The economic advantages of eradicating tuberculosis from farm animals are too apparent to require extended discussion. They will come to the individual stock raiser and dairyman as well as to the public and the nation. Breeders are beginning to understand that it is unprofitable to go on raising cattle while tuberculosis exists in their herds. The practice is becoming more general for buyers of breeding and dairy cattle to have such animals tested before placing them in their herds, and the breeder who can give assurance that his herd is free from tuberculosis has a decided advantage in making sales. With the agitation in favor of a more wholesome milk supply there is coming a growing demand for milk from healthy herds at higher prices, and as this demand increases the dairyman who can not show a clean bill of health for his cows will find it more difficult to market his products.

To overcome the great losses before mentioned is worth considerable effort and expense. The benefits to follow from the eradication of tuberculosis from farm animals are so great and so obvious that the necessary expenditures, even though they must be heavy, may be regarded as a highly profitable investment.

THE RELATION OF THE TUBERCULOUS COW TO PUBLIC

HEALTH.

By E. C. SCHROEDER, M. D. V.,

Superintendent of the Bureau Experiment Station.

INTRODUCTION.

Under the conditions of our present civilization the dairy cow fills a unique place. Her living body is the source of the most important of all human foods; she has become an essential factor among our modern institutions; remove her and either a substitute must be found or many thousands of young children will die of starvation. The woman who can feed her infant at her own breast until it is old enough to thrive without milk is probably nearer the exception than the rule, so that either the cow or some other milk-producing animal must, as a sheer necessity, be available to serve the purposes of a human foster mother. After children have passed the period during which milk is a requisite article of food, most of them continue its use as a beverage and add butter to their diet as a second product from the cow. Later on cream and cheese are added, and the use of milk to some extent as a beverage, and of cream, butter, and cheese as regular, current articles of food is continued to the end of life. Hence, even if we are not greatly influenced by the idea that it is disgusting and barbarous to eat substances that are obtained from the living bodies of diseased cows, we must feel that it is important to make a careful inquiry regarding the transmissibility to ourselves, through the use of dairy products, of the commonest disease with which dairy cows are affected. The need for this inquiry is emphasized by the knowledge that the commonest and most important disease of cows is also the commonest and most important disease of mankind, and by the fact that, though the disease in questiontuberculosis is one of the few infectious diseases to which widely different species of animals are susceptible, its commonest victims are persons and dairy cows.

The indispensable cause of tuberculosis is the multiplication of tubercle bacilli in the animal body. Bacilli do not grow and multiply in animal bodies until they have been introduced into them from without, and tubercle bacilli grow and multiply nowhere else in nature. The propagation of tuberculosis, therefore, depends upon the

tubercle bacilli that emanate from the bodies of tuberculous individuals, human and animal, and the widespread and common occurrence of tuberculosis is due to the unguarded and dangerous expulsion and dissemination of tubercle bacilli by the victims of tuberculosis. This is the basis for the practically unanimous conclusion among those who are informed on the subject that, in our fight for the suppression and eventual eradication of tuberculosis, we must strive to control and make harmless all the sources from which tubercle bacilli are scattered.

As persons and dairy cows are the commonest subjects of tuberculosis, they are also the commonest sources from which tubercle bacilli emanate, and as the exposure of persons to persons, through the ordinary routine of life, and the exposure of persons to dairy cows, through the lifelong use of dairy products, are commoner and more direct and intimate than the exposure of persons to other possible sources of tuberculous infection, we may conclude that the two most important sources of tubercle bacilli, against which public health must seek to defend itself, are tuberculous persons and tuberculous dairy cows. Of these two sources the former is probably the more important, but only little can be said about it here, as the latter is the subject of this article, and the little that is permissible must be limited to the infection of dairy products when they are exposed to tuberculous or consumptive persons.

Persons affected with tuberculosis of the respiratory passages, lungs, throat, etc., expel tubercle bacilli with their sputum and with the particles of fluid sprayed from their mouths and noses during accelerated expiratory acts. Such persons are regarded as not necessarily dangerous to public health when they observe a number of simple precautions relative to the disposal of the infectious material. which they expel from their bodies, but they can not keep their environment sufficiently free from tubercle bacilli to make it a safe place for the exposure of food that is to be eaten by others. Dairy products are usually eaten in a raw state; that is, without previous exposure to a germicidal process like cooking, and hence it is especially desirable that they should not be handled by, nor be exposed in the environment of, tuberculous persons.

The expulsion of tubercle bacilli by those who are affected with tuberculosis and the mode of its occurrence justify the enforcement of health regulations that will exclude all tuberculous persons from serving in occupations such as food venders, cooks, waiters, milkers, creamery employees, butter makers, etc. This statement may appear to some persons as savoring a little of that inordinate fear of tuberculosis which has been discussed by many writers under the name of phthisiophobia, but for that reason it can not be lightly dismissed, especially as even positive phthisiophobia has not been proven to be