Lung Plague of Cattle. 649 



liad extended into 20 different townships in Mass. In i860, a 

 State Commission was created, with Dr. E. F. Thayer as veterin- 

 ary commissioner, and in the next few years they destroyed 

 1,164 cattle, and stamped out the plague at a total cost of 

 ^77,5.11.07. 



An importation of infected cattle into I^iSw Jersey was made in 

 1847, by Mr. Richardson, who on discovering the nature of the 

 •disease, made an end of that particular contagious centre, by 

 slaughtering his whole herd at a cost of $10,000. 



South Africa was infected in 1854 by the landing bf a Dutch 

 bull at Cape Town. As there were no railroads and all inland 

 •carriage was conducted by ox-wagons, it soon spread over the 

 ■colonies and extended thence into the native states, and has con- 

 tinued to the present time. 



Australia was infected in 1859 through an English cow landed 

 at Melbourne. When the disease was identified, the whole herd 

 was slaughtered and paid for, and the farm quarantined. But 

 the quarantine was broken by a teamster turning his work-oxen 

 into the pastures under cover of night, and the infection escaped 

 and has prevailed over Australia to the present day. 



Later the disease extended in a similar manner, to Tasmania 

 and New Zealand. 



Causes. The one essential cause of lung plague is contagion 

 from a preexisting case. Before the days of bacteriology, this 

 had been demonstrated as conclusively as any truth can be. All 

 •extensions into a new country or district could be traced to direct 

 importation from a preexisting area of infection. Until such im- 

 portation such lands have been immue from time immemorial ; 

 at once after, the infection has spread from the imported animals 

 as a centre ; if the stock is divided up and scattered, several pri- 

 mary centres are formed from each of which the plague makes 

 extension. Again, isolated islands (Channel Islands) and purely 

 breeding districts (Scottish Highlands) into the herds of which 

 aio store cattle from outside are admitted, remain immune through 

 centuries, no matter how prevalent lung plague may be in the 

 countries immediately around. The immemorial immunity of 

 the Western Continent, up to the date of the arrival of the now 

 famous Dunn cow, the continued immunity of Canada and 

 Mexico after the infection of the Eastern United States, and the 



