35 The Lung Plague of Cattle. 



pressed from thera were administered to animals without 

 any bad result. Even if we could rely on such negative 

 testimony, they would be of slight significance, as the 

 food devoured by the ox is at the same time breathed 

 upon, and any existing virus is likely to be directly in- 

 haled. 



Aotmals Susceptible. 



Unlike the other great cattle plagues (Einderpest and 

 Aphthous Fever) this confines its ravages to the bovine 

 genus. Currency has at different times been given to re- 

 ports of the infection of sheep, goats and deer, but the 

 transmission of the malady to these animals has never 

 been satisfactorily proved. In Great Britain sheep have 

 mingled in the fields with infected cattle for thirty-seven 

 years without any observed transmission of the malady 

 to the sheep. The same is true of Australia and the 

 Cape of Good Hope, where the plague has driven many 

 colonists to replace their cattle by sheep. Goats live. in 

 a large proportion of the stables in New York and Brook- 

 lyn, yet we have never seen a goat infected. As respects 

 deer, the lung plague prevailed for a series of years in 

 the deer park at Biel, Scotland, but the deer never suf- 

 fered. These, it is true, are but negative proofs ; they 

 show only that in certain climates and conditions expo- 

 sure fails to produce infection ; what might occur in a dif- 

 ferent environment which materially modified the disease, 

 remains to be shown. At present there is no reliable 

 testimony that other animals than cattle will contract the 

 affection. 



Among cattle no race, breed nor age materially modi- 

 fies the susceptibility. In countries where the malady 

 has prevailed for centuries the attacks are somewhat less 

 severe; but this holds true of all plagues of man or 

 beast. In time the more susceptible races die off, and 

 by a natural selection the survivors have the diseas' in a 



