Page:Popular Science Monthly Volume 69.djvu/247

Rh even anticipated those of Behring. By using for injection first tuberculin and then in succession tuberculin and tuberculous material containing bovine and possibly human tubercle bacilli, McFadyean succeeded in increasing the resistance of several cattle to artificial tubercular infection.

Pearson and Gilliland, 1902, in this country early published accounts of some experiments which they carried out upon the immunization of cattle from tuberculosis. They employed a culture of human tubercle bacilli for producing immunity and found that subsequently the protected animals, as compared with the controls, which all succumbed to the virulent inoculation, either developed no lesions or very inconsiderable ones upon being given large quantities of highly pathogenic bovine cultures. As far as I know these experimenters are the only investigators who have endeavored to carry the principles of the method a step farther, so as to bring about arrest of the disease in cattle already tuberculous. While it is unlikely that such a therapeutic use of 'Vaccination' will ever be made in veterinary practise, the facts are of considerable theoretical interest, especially in view of the somewhat similar means employed to arrest tuberculosis in man.

The immense importance to scientific agriculture of the matter of immunization of cattle from tuberculosis and the even greater collateral interest which the subject has for man, as enlarging the possibilities of immunity even for him, have led to a discussion on the priority of the discovery between Neufeld, a pupil of Koch, and Behring. It would appear from Neufeld's writings that, while working under Koch's direction, he ascertained as early as 1900-1901 that large animals—donkeys chiefly, but cattle also—could be protected from artificial infection with virulent tubercle bacilli, always fatal to control animals, by previous treatment with tubercle vaccine, of which several different preparations were studied. It is not within the scope of this address to apportion the credit of priority; but in any case, assuming the facts to be as stated by the contestants, McFadyean should receive as great credit as either of the others, if not the chief credit. The principle which all the investigators employed is not new in experimental medicine, but has come to us from the genius of Pasteur. It may, however, be said that our knowledge of the tubercle bacillus and its varying activities had by the year 1900 become so much enlarged that the possibility of putting the facts of the newly discovered properties to a practical test of immunity occurred to the several independent workers in bacteriology. There can, I think, be no doubt that Behring deserves the credit of making the protection of cattle from tuberculosis a feasible, practical object of study. This alone is a merit of no small order.

From the mere fact that cattle have been successfully protected from infection by the tubercle bacillus, even under the severest