Lung Plagtce of Cattle. 653 



the case at Quincy, Mass. , in which a farmer coming straight 

 from the slaughter of sick cattle, infected his own herd ; also the 

 case of Mr. Jewell, of Ivong Island, who carried the infection 

 from the herds visited, to his own family cow in a thoroughly se- 

 cluded stable. 



Infection through infected and emptied stables, was a common 

 experience in dealing with the lung plague in America. Cows 

 kept alone and only introduced after the predecessor had died 

 habitually contracted the disease, though brought, through the 

 most carefully guarded stockyards, from healthy districts. Stable^ 

 have continued infecting for a year after having been vacated, 

 (Friedberger and Frohner). 



Infection through manure spread on ground to which susceptible 

 cattle had access was an occasional occurrence. 



An active unrestricted commerce is however the most prolific 

 means of infection in cultivated countries. Slowly as the disease 

 progresses, and long as the animal diffuses infection, it soon at- 

 tacks and kills or immunizes all the susceptible animals in the 

 single herd, and if no other susceptible animal is bought or born 

 into the herd, the germ in due time loses its pathogenic potency 

 and infection is at an end. In this way many centres of infection 

 started in herds on well fenced farms have worn themselves out. 

 But the case was far otherwise in the city dairies and swill stables. 

 The trade demanded that the stalls emptied by death should be 

 filled up to consume the swill, or supply the milk route and thus 

 fresh susceptible cattle were constantly exposed in the infected 

 stable. The dairy cows were supplied by dealers who charged 

 exorbitant prices for them and held a chattel mortgage for the 

 amount. Tney had come through the infected dealer's stable 

 and if they did not come up to the milk yield promised, they 

 were either passed on to another dairy or returned to the dealer's 

 stable carrying back a new load of infection. The wagons used 

 to carry the cows through the city were constantly infected and 

 infecting. The swill stables became the final destination of the 

 surviving cows that had gone dry and thus infection constantly 

 gravitated into them. 



In Europe where the great cattle and meat trade with England 

 and the constant demand for cattle to consume the marc of the 

 beet sugar and other factories, cause a continuous draught upon 



