THE DISEASES OF CATTLE 289 



through years of observation is that blackleg was seldom 

 known in the early days of the range business when the 

 herds were bred altogether from the old long-horned 

 animals of the Southwest. It will hardly do to say 

 absolutely that the scrub will not contract blackleg but 

 it is very likely that if a careful watch were kept of the 

 progress of the disease in a bunch of 100 pure-bred year- 

 lings and 100 scrubs, all grazing on the same range, and 

 under identical conditions, a large majority of the losses 

 would be among the pure-breds. 



Blackleg is not what the medical fraternity calls a 

 sporadic disease. It cannot originate through certain 

 physical conditions on a range where it was never be- 

 fore known. It must have been conveyed there through 

 the death of some afflicted animal which, dying, carried 

 into the ground the bacilli of the disease. Just how long 

 the bacilli lie dormant in the ground is not known. I 

 know of one case in Arizona where a yearling dying of 

 blackleg was buried several feet deep on the banks of 

 a creek near a watering-place. Six years later the 

 caving of the bank along the creek uncovered the bones 

 of the animal and not long after there was an outbreak 

 of blackleg in the adjacent pasture. As there had never 

 been but one known death from the disease before, and 

 since the cattle were in the habit of lying along the 

 creek in the shade of the high banks, there was little 

 reason to doubt that the disease was taken into the ani- 

 mals' systems through small cuts on their bodies com- 

 ing in contact with the ground, or perhaps licking them- 

 selves or one another, and thus carrying the deadly 

 bacilli into their circulation through sore places or 

 cuts upon the inner parts of the lips or tongue. That 

 this is possible has been repeatedly proved by experi- 



