120 JOHNE'S DISEASE 



One intradermic test on Case III. with concentrated 

 human tuberculin gave a "pronounced" reaction. 



Two endermic tests with concentrated human tuber- 

 culin were negative (Cases XVI. and XVIII.). 



The authors do not state the conclusions to be 

 drawn from their experiments, and insufficient avian 

 ophthalmic, intradermic, and endermic tests have been 

 made to condemn these methods of diagnosis; but it 

 seems improbable that these tests will be of more than 

 scientific interest. 



With regard to the avian tuberculin used as a sub- 

 cutaneous test, the number of negative results may be 

 due partly to the fact that the cases tested were some- 

 what advanced. O. Bang has found that very advanced 

 cases do not react, and this, of course, is true with 

 tubercular cattle inoculated with bovine tubercuhn. 



In many cases the temperature reactions obtained 

 were not high, in spite of the large doses given — a 

 result which is in agreement with what we have 

 already stated in the beginning of this chapter with 

 regard to heterogeneous vaccines. The results ob- 

 tained by O. Bang were, however, the best that could 

 be got in the absence of pure cultures of the bacillus. 



In 1910 the present writers started experimenting 

 on Johne's disease with the object of cultivating the 

 causative bacillus and of preparing a reliable and 

 specific diagnostic vaccine from the cultures obtained. 

 After cultivating several strains of the bacillus on 

 solid media, these strains were subcultured on to fluid 

 media {vide Chapter VI.), and from these cultures 

 vaccines were prepared. 



Vaccine No, i. — In the first experiments we used an 

 alkaline peptone-bouillon containing 4 per cent, of 

 glycerine and i per cent, of dried human tubercle 

 bacilli. This was placed in Duclaux flasks, and steri- 



