Emphysematous Anthrax. 183 



mer and autumn. It is not uncommon at the breaking up of the 

 winter snows. It is especially prevalent on damp, undrained 

 land or on such as has dried up in the heats of summer, and has 

 become less prevalent in many localities in connection with drain- 

 age and careful cultivation. 



Animals susceptible. The disease is especially common in 

 young cattle, from three months to four years of age. Calves 

 fed on milk are rarely attacked, being in a sense carnivorous and 

 sometimes immunized by toxins from the dam. Cattle over four 

 years usually escape, having already become immune if kept in 

 an infected locality. If brought from a non-infected place they 

 are, at any age, as susceptible as the young. Sheep and goats 

 contract the disease only exceptionally, but like the Guinea pig 

 are easily infected by inoculation. Horses, asses and white rats 

 have only a circumscribed swelling in the seat of inoculation, 

 and foals and buffalo calves sometimes contract it casually. 

 Carnivora and omnivora, (dog, cat, pig, bird, man), and the 

 rabbit are virtually immune. 



Immune animals may, however, be made to succumb under 

 special treatment. In a rabbit inoculated at the same time with 

 the microbe of black quarter and proteus vulgaris, or micrococcus 

 prodigiosus, or if injected with a little lactic acid, the disease de- 

 velops promptly and fatally. Over-exertion, producing sarco- 

 lactic acid will also lay the sy.stem open to attack. The reduc- 

 tion of the vitality and re.sistance of the muscle of the rabbit by 

 a contusion, bruise or lacerated wound, or by injecting it with 

 acetic acid, potash salts, alcohol, or common salt, will render the 

 inoculation pathogenic. Again, the introduction of the black 

 quarter microbe into the aqueous humor of the rabbit, where 

 there are so few defensive leucocytes, entails an active prolifera- 

 tion and a fatal result. 



Causes. The essential cause of emphysematous anthrax is a 

 rod-shaped germ, variously known as bacillus anthracis em- 

 physematosa, bacillus Chauvaei, Rauschbrand bacillus. 

 This is a rod-shaped microbe, with rounded ends, found singly 

 or connected in pairs, or very short filaments. The bacilli are 

 3 to lo/i long, by .5/«. broad, or when sporulating, i.i to i.3jit. 

 They form spores even in the body of the affected animal, often 

 assuming a club shape by reason of the spore formation near one 

 end. If the spore develops in the center they appear fusiform. 



