No, 7. DEPARTMENT OF AGRICtTLTURE. 147 



experimented with iu this field it would not be fair to bold out the 

 hope that tuberculous cattle may be successfully treated. No doubt 

 many cattle in the earlier stages of tuberculosis may be aided, some 

 may be cured. Where the Bang system for controlling tubercu- 

 losis is in use it may be serviceable to vaccinate the infected ani- 

 mals that are probably recently affected for the purpose of prolong- 

 ing their period of usefulness. But the difficulty is that after the 

 animal has been treated in this way and for a year or more appears 

 to be in perfect health and may have ceased to respond to the tuber- 

 culin test, a great deal of fortitude is required to continue to keep 

 that animal in isolation, there develops such a strong tendency to 

 break over the barriers and place it with the sound herd. But to do 

 so would-be to take a risk that is not justified in the present state 

 of our knowledge. We can not be certain that the cow is cured until 

 the postmortem examination and, unfortunately, the animal does not 

 lend itself to more than one such examination. So the treatment 

 of tuberculosis of cattle by vaccination is at present an interesting 

 and, I may say, a promising subject for scientific study rather than 

 a practical procedure. 



''The study of vaccination is by no means exhausted. There are 

 still many points to be elucidated and the methods are to be still 

 further developed and, I hope, simplified. We have some experi- 

 ments going that are very suggestiA'e and that encourage this hope, 

 and effort. Of course such work requires considerable time, es- 

 pecially experiments to determine the duration of immunity. 



''Already there are different methods in use. A German firm is 

 putting on the market and pushing a dry vaccine that is made by dry- 

 ing tubercle bacilli of human type and then by grinding them slight- 

 ly. By this process they are weakened. The dry bacilli are taken 

 up in salt solution and injected into the circulation. This is the von 

 Behring method. The comparative experiments that have been made 

 show that this vaccine is not so effective as vaccine prepared by our 

 method. Convincing evidence on this point has been furnished by 

 Hutyra and is published in von Behring's own journal. This is 

 also the conclusion of Koch and Schuetz and is confirmed by others. 



"It is quite premature to apply vaccination against tuberculosis 

 promiscuously — to exploit it commercially. In France, Italy and 

 other countries the question is still reserved for scientific study, 

 under government grants (several of which are reported in the Sep- 

 tember number of the Kevue Generale de Medicine Veterinaire). 

 Lest the use of vaccination be controlled in some way it is likely to be 

 misused and to lead to disappointment, if not to fraud and to the dis- 

 semination of disease. This control should not be left in the hands 

 of a commercial house interested in placing the greatest possible 

 amount of product on the market. As with tuberculin, anthrax vac- 

 cine, etc., the character of the product and its proper use should be 

 controlled by appropriate public authority. Pennsylvania has al- 

 ready enacted legislation to prevent the misuse of vaccine and the 

 use of dangerous vaccines. 



"Vaccination against tuberculosis is free in this state so far as 

 the resources of the State Livestock Sanitary Board will permit. 

 The process is useful in all breeding herds where there is tuberculo- 

 sis and by its use sound animals can be produced from tainted an- 

 cestry more easily and surely than by the Bang method and their 



