24 The Lung Plague of Cattle. 



of other European nations, as well as Massachusetts and 

 Connecticut. The remark is as true to-day of Western 

 Europe and America as it was a century ago when made 

 by the immortal Haller of his own native Switzerland, 

 that the disease never appears but as the result of the intro- 

 duction into a country or district of an animal from an in- 

 fected place." 



Can the Bovine Lung Plague be Transmitted bx 

 Mediate Contagion ? 



This question will be best answered by adducing a few 

 instances of the infection of animals otherwise than by 

 immediate contact. These wiU be arranged under dif- 

 ferent headings according to the channel through which 

 the contagion was conveyed. 



A. Contagion through the Atmospliere. — Some years ago, 

 the hypothesis was advanced in England that this 

 disease could not be conveyed from animal to animal 

 by mediate contagion, but that, in order to its transmis- 

 sion, the sick animal must be brought into direct con- 

 tact with the healthy. It is difficult to see how such 

 an absolute claim can be advanced in the face of the 

 every-day observation that, when a sick animal is intro- 

 duced into one end of a stable, the plague often skips 

 many intervening ones to strike down a beast near the 

 farthest end of the building. In such a case the air is 

 the medium through which the virus is carried, and the 

 contagion is unquestionably mediate. 



The experiments conducted at the Brown Institution, 

 in September, 1876, March, 1877,. and August, 1878, in 

 which healthy cattle were exposed to the emanations from 

 diseased lungs without any ill result, are quoted as dis- 

 proving contagion through the air. But one or several 

 failures to convey a disease is no proof that the disease in 

 question is not contagious. I might quote the example 

 of the enthusiastic non-contagionists who clothed them 

 selves with the linen fresh from the bodies of cholerj 



