186 



EXPERIMENT STATION RECORD. 



showed the greatest gain of any in the tested lot. Previously it had 

 been unthrifty and irregular in its weekly gains. 



In connection with this subject the resolutions of the United States 

 Veterinary Medical Association in 1805 relative to tuberculosis and the 

 tuberculin test are quoted, after which the author proceeds with the 

 subject in connection with Minnesota cattle. The following table, in 

 which the results of 3,430 tests are summarized, shows that the disease 

 prevails most among the pure breeds, city dairies, in cases of poor 

 stable conditions, and of poor ventilation: and, further, that good 

 stables and ventilation do not necessarily prevent infection. 



Prevalence of tuberculosis according to class and condition. 



Class. 



1 . Natives 



2. High grades 



3. 1'iiro breds 



4. City dairy herds 



5. Farm herds 



0. In "good' ; general condition of stables. 



7. In "fair" condition of stables 



8. In "poor" condition of stables 



9. Willi "good " ventilation 



10. With "fair" ventilation 



11. With "poor" ventilation , 



Number 



of re- 

 actions. 



Per cent 

 tuber- 

 culous. 



223 7. 8 

 17 10.8 

 43 16.6 

 284 10.4 

 99 14.2(7.8)' 

 139 10.1(6.8)' 

 83 7. 28 

 165 19.1 



9.8(5)1 

 6.16 

 16.6 



99 

 67 



201 



'Fifty-five of these tuberculous animals in each case (groups 5, 6, and 9) were from the same 2 

 herds. Eliminating these 2 herds from groups 5, 6, and 9 the percentages are reduced, respectively, 

 to 7.S, 6.8, and 5. 



The 11.1 per cent of the 3,430 animals here shown to be tuberculous 

 must not, wo are told, be understood to represent the cattle of the 

 State, for few farm herds have been tested as compared with breeding 

 herds and city dairies. These have been shown by general experience 

 to be more subject to attack than farm herds or native stock subject to 

 only ordinary conditions. But such results must not be taken, it is 

 added, as an argument against founding herds of pure breeds, though 

 it may be taken against founding a herd on tuberculous stock. 



Another table gives the results of the examination of some 27 herds 

 numbering 772 head of cattle, of which 15.5 per cent were found tuber- 

 culous and 70 of the 71 of which posi-mortem examinations were made 

 proved so. Another table locates the disease as shown by the post- 

 mortems. A large percentage of the animals shows disease of the lungs 

 and neighboring glands and pleura, indicating the air as the common 

 source of infection. 



Further, there are discussed experiments with tuberculin to deter- 

 mine the accuracy of the test, the circumstances under which animals 

 may fail to react, whether it is injurious to sound or to tuberculous 

 cattle, whether a cure or merely an immunity from tuberculin has 

 been effected when no reaction occurs after one or more injections, the 

 diagnostic value of the retests as compared with the first, the possi- 



