466 MSRiSES OF CATTLE. 



the significance of the spore of the anthrax bacillus applies equally 

 well to these bodies. They resist destructive agents for a consider- 

 able length of time, and may still produce disease when inoculated 

 after several years of drying. Tliis fact may account for the occa- 

 sional appearance of blackleg in stables. In order to meet the require- 

 ments for the development of the spores, which takes place only in 

 the absence of the atmosphere, it is necessary that the wound be very 

 small and deep enough to penetrate the subcutaneous tissue. 



Several observers have found this organism in the mud of swamps. 

 By placing a little of this mud under the skin the disease has been 

 called forth. 



Since the disease may be produced by placing under the skin 

 material containing the specific bacilli and spores, it has been as- 

 sumed that cattle contract the disease through wounds, principally 

 of the skin, or very rarely of the mouth, tongue, and throat. Slight 

 wounds into which the ^irus may find access may be caused by barl)ed 

 wire, stubbles, thorns, briers, grass burs, and sharp or pointed parts 

 of food. 



The symptoms of blackleg may be either of a general or a local 

 nature, though more frequently of the latter. The general symptoms 

 are very much like those belonging to other acute infectious or bac- 

 terial diseases. They begin from one to three days after the infec- 

 tion has taken place with loss of appetite and of rumination, with 

 dullness and debility, and a high fever. The temperature may rise to 

 107° F. To these may be added lameness or stiffness of one or more 

 limbs, due to the tumor or swelling quite invariably accompanying 

 the disease. After a period of disease lasting from one to three days 

 the affected animal almost always succumbs. Death is preceded by 

 increasing weakness, difficult breathing, and occasional attacks of 

 violent convulsions. 



The most important characteristic of this disease is the appear- 

 ance of a tumor or swelling under the skin of the affected animal a 

 few hours after the setting in of the constitutional symptoms de- 

 scribed above. In some cases it may appear first. This tumor may be 

 located on the thighs (hence " blackleg," " black quarter "), the neck, 

 the shoulder, the breast, the flanks, or the rump; never below the car- 

 pal (or knee) and the hock joint. It more rarely appears in the throat 

 and at the base of the tongue. The tumor, at first small and painful, 

 spreads veiy rapidly both in depth and extent. "When it is stroked 

 or handled a pe<;uliar crackling sound is heard under the skin. 

 This is due to a collection of gas formed by the bacilli as they 

 multiply. At this stage the skin becomes dry, parchment-like, and 

 cool to the touch in the center of the tumor. If the swelling is cut 

 into, a frothy, dark-red, rather disagreeably smelling fluid is dis- 

 charged. The animal manifests little or no pain during the operation. 



