lOO AGRICULTURE OF MAINE. 



man who took care of the other herd and who changed his outer 

 clothing and his shoes and washed his hands when he went into 

 the barn with the sound herd. We have tested the herd every six 

 months, it was tested a few days ago, and we have had no trouble 

 with the sound herd. We have had to remove only one ani- 

 mal from it. In the diseased herd some of the animals broke 

 down, but several of them that were younger animals at the 

 time of the beginning of the test went through to the end of the 

 test, and were killed and examined at that time. While they 

 were all infected, some of them w^ere infected only to a very 

 slight degree and in two or three cases the infection was practi- 

 cally encysted. When we had replaced our herd we killed all o£ 

 the animals in the diseased herd, to discover their condition. 

 We did not care to keep them any longer, as we did not want 

 the trouble of keeping an extra herd and an extra attendant. 



Dr. Newcomb — Dr. Russell has treated very thoroughly 

 the subject of tuberculosis and has mentioned protective inocu- 

 lation. I would like to describe to you briefly the method of 

 Prof. Von Behring and some of his success. Prof. Von Behring,. 

 after having discovered the anti-tocsin for diphtheria, turned his 

 attention to the relations between human and bovine tuberculosis. 

 He discovered that by inoculating cattle with the germ of human 

 tuberculosis they were rendered immune to the bovine germ 

 under certain conditions, and it took him some time to find out 

 what those conditions were. Dr. Russell told you of the atten- 

 uated virus. It took some time to prove all this. The principle 

 is the same as that employed in vaccinating against smallpox, 

 in which instance the bovine virus is introduced into the human 

 subject. The material employed in this vaccination is derived 

 from the culture of the human tubercle bacillus so treated as to 

 destroy its virulence. It is not a lump of serum or a mass of 

 dead germs, but living germs which give, during the process- 

 of their absorption into the system, an immunity. Animals best 

 suited for this vaccination are calves from two weeks to three 

 months of age, although animals up to one year of age may be 

 vaccinated, provided they have been previously tuberculin tested 

 and do not respond to the test. Even if there is incipient tuber- 

 culosis there is a tendency to cure or arrest such disease, and the 

 acquirement of immunity against natural infection. This cura- 



