Contagious and Epizootic Diseases. 33 



calities, in lierbivora, swine and birds, and commtinica- 

 ble by inoculation to other animals and to man. It 

 shows itself by many different forms, all characterized by 

 extreme changes in the chemical and vital properties ol 

 the blood, breaking down of the blood-globules, extrava- 

 sations of blood or albuminous fluids in different parts of 

 the body, with a tendency to gangrene, yeUow or brown 

 mucous membranes, enlargement or even rupture of thd 

 spleen (milt), and a very high mortahty. 



Causes. It is propagated by contagion but tends to die 

 out when produced in this way only. It is transmitted by 

 contact with the blood, hquid exudations, portions of the 

 diseased carcass, fat, skins, hair, wool, bristles, feathers, 

 and bowel evacuations, and rarely or not at all through 

 the atmosphere. Simple contact of these matters with the 

 healthy skin of a susceptible subject is enough to produce 

 the disease. The virus is most potent when received from 

 an animal still living or only recently dead, and yet may 

 be preserved for months in aU conditions of climate, tem- 

 perature and humidity. 



Eating of the flesh of animals killed while siiffering in 

 this way has often conveyed the disease in spite the cook- 

 ing to which it was subjected. Fifteen thousand of the 

 inhabitants of St. Domingo once perished in six weeks 

 from this cause, and a whole family was poisoned a few 

 years ago in Aberdeenshire, Scotland. The Tartars perish 

 in great numbers from eating their anthrax horses. Mos- 

 quitoes and other msects with perforating apparatus to the 

 mouth probably help to commimicate it as nearly aU cases 

 in man occur on exposed parts of the body. 



Its development in a locaHty is determined : 1. By the 

 rich surface soil abounding in organic matter, and tlie im- 

 pervious subsoil preventing natural drainage. 2. The fre- 

 quent inundations of banks of rivers flowing through level 

 countries and the drying up of ponds and lakes leaving 

 much organic deposit in then- basins. 3. A continuation ol 

 warm, dry weather which favors organic emanations fron: 



