FIG. 60.-TUBERCULOSIS OF THE INTESTINAL (MESENTERIC) GLANDS.

retaining are killed. The premises are thoroughly disinfected. The reactors and non-reactors are kept entirely separate, being stabled, pastured and fed distinct from each other. The milk from the reacting animals fed to calves is pasteurized by heating to about 185 degrees Fahrenheit. Frequent examinations are made of the reacting cattle and as soon as any show evidence of unthriftiness or become undesirable, they are slaughtered. The young of the reactors are kept entirely isolated from their mothers and other adults, and are tested as soon as they are of suitable age.

The reactors, if any, are usually killed; those passing the test being placed with the healthy group. The healthy herd is tuberculin tested at about six month intervals and any reactors are immediately placed with the diseased herd or destroyed.

The Bang system is in use on a number of farms in New York State at the present time and has met with considerable success. Some years ago the herd of the Geneva Experiment Station was found to be tuberculous and this plan was put in operation and healthy young animals raised from the diseased cattle with very little loss.

The object of this plan is to eventually produce a healthy young herd to replace the old. Its success depends on many factors, among them being careful pasteurization of the milk, frequent thorough examination of the animals, and the prevention of infection reaching the calves from any source. Its practical value seems to be greater in herds of valuable pure-bred animals and it is doubtful whether it should be attempted except in herds of moderate size. Under ordinary dairy conditions in New York State the feasibility of this plan is questionable unless two distinct sets of buildings are available. On the ordinary farm, the inconvenience necessary in heating the milk daily, the proper isolation of both the mature and young animals and the constant attention to all details should be considered before adopting this method.

PHYSICAL EXAMINATION

Owners of herds, who object to the use of tuberculin should consider the possibilities of the physical examination as a means of controlling the disease. This plan has been followed with more or less success under the supervision of some of our larger milk companies. It is believed that most animals will show evidence of abnormal conditions before they become distributors of the germs of tuberculosis. This scheme, of course, contemplates the finding of so-called spreaders or those in the advanced stage of the disease, and does not presume to detect all that are affected. It is of considerable value, no doubt, in the hands of a competent veterinarian, and while a slower and probably less certain means of checking the spread of the disease in the dairy herd is nevertheless not as expensive as attends the use of tuberculin; and many animals with

udder or advanced tuberculosis could be detected in this way, thereby materially decreasing the number of tubercle bacilli in the milk of the herd.

CONTROL OF THE DISEASE

In attempting the control or eradication of tuberculosis from a herd it should be considered that the disease is tardy in development and is often correspondingly slow in eradication. We must constantly guard against re-infection of the herd, which is always possible. In this connection it should be remembered that tuberculosis is produced only by the bacillus of tuberculosis. There fore if these germs are prevented from gaining entrance to the body of the bovine animal the disease cannot occur in our dairy herds.