448 DISEASES OF CATTLE. 



Plate XXIX, fig. 4, this is represented as an uncolored spot located in 

 one end of the rod, which is enlarged so that the rod itself appears 

 more or less club-shaped. What has already been stated concerning 

 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. This fact may account for the occa- 

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

 requirements for the development of the spores, which only takes 

 place 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 mate- 

 rial containing the specific bacilli and spores, it has been assumed 

 that cattle contract the disease through wounds, principally of the 

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

 into which the virus may find access may be caused by barbed 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 appearance 

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

 hours after the setting in of the constitutional symptoms described 

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

 located on the thighs (hence "blackleg," "blackquarter"), the neck, 

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

 carpal (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 very rapidly both in depth and extent. When it is 

 stroked or handled a peculiar 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 dig- 



