13 



tH)j)eai's to be abiiudant i)foof of it, a single iiifoctccl animal l)roiig"ht 

 into a held of cattle may communicate the disease to every animal 

 in the herd. Infection by the generative organs has been doubted, 

 but Zippelius and others state, however, that they have observed 

 instances in which the infection could not have occurred by any other 

 means. Bollinger produced tuberculosis in pigs, by Jeeding thrm for 

 a long time on milk from tuberculous cows. 



A large percentage of the animals suffering with tuberculosis are 

 most seriously affected in the lungs, and it seems probable that these 

 were infected b}' the bacilli which gained access with the inspired air. 



In the winter of 1885-6, an outbreak of tuberculosis occurred in 

 the herd of fifty-one animals on the State College farm at Orono, 

 Maine. There had been an occasional case in the herd for eight or 

 ten years previous to that time, but it was uot then known to be 

 tuberculosis. Late in the autumn of 1885, a cow was attacked with 

 a husky cough which increased in severity, and becoming much 

 emaciated she was killed about the last of January, when her lungs 

 were found to be badly diseased. About the same time three others 

 were •' affected with slight husky cough, and, by the end of February, 

 most of the aaimals in the herd commenced coughing almost simul- 

 taneously." In fact the disease had become epidemic in the herd, 

 and an examination made by Drs. Michener and Bailey revealed tiic 

 fact that nearly all the animals in the herd were more or less affecti'd 

 with tuberculosis. By order of the Cattle Commissioneis the entire 

 herd was then slaughtered and buried. 



Such epidemics are apparently uncommon, and it is impossible to 

 say what caused the sudden and general outbreak at that time. The 

 feeding, as reported by Dr. Michener, was judicious in every sense, 

 and the hay and grain of the best quality. The history of this out- 

 break, from the time when the disease first appeared until the animals 

 were slaughtered, proves conclusively that tuberculosis is both con- 

 tagious and hereditary. The animals were watered from a tub into 

 which the water was pumped from a cistern in the cellar of the barn, 

 and any discharges from the lungs of an infected animal could very 

 easily have fallen into the water, and been taken up by the others 

 drinking from the tub. It is quite certain, however, that many of 

 these animals )-eceived the disease by inheritance, while others prob- 

 ably inhaled it. It is a noteworthy fact that four horses were kept in 

 the barn with some of the worst cases, and did not take the disease, 

 which simply indicates that the horse is much less susceptible to it 

 than the bovine race. 



