458 DISEASES OF CATTLE. 



cal or rodlike, measuring ^^Vtt to ^^Vtt inch in length and sjU-s inch 

 in diameter. Like all bacteria, these rodlike bodies have the power of 

 indefinite multiplication, and in the bodies of infected animals they 

 produce death by rapidly increasing in numbers and producing sub- 

 stances which poison the body. In the blood they multiply in num- 

 ber by becoming elongated and then dividing into two, each new 

 organism continuing the same process indefinitely. Outside of the 

 body, however, they multiply in a different way when under condi- 

 tions unfavorable to growth. Oval bodies, which are called spores, 

 appear within the rods, and remain alive and capable of germina- 

 tion after years of drying. They also resist heat to a renuirkablo 

 degree, so that boiling water is necessary to destroy them. The 

 bacilli themselves, on the other hand, show only very little resistance 

 to heat and drying. It has long been known that the anthrax virus 

 thrives best under certain conditions of the soil and on territories 

 subject to floods and inundations. The particular kinds of soil 

 upon which the disease is observed are black, loose, warm, humous 

 soils, also those containing lime, marl, and clay, finally peaty, swampy 

 soils resting upon strata which hold the water, or, in other words, are 

 impervious. Hence fields containing stagnant i:)Ools may be the source 

 of infection. The infection may be limited to certain faiTns, or even 

 to restricted areas on such farms. Even in the Alps, over 3,000 feet 

 above sea level, where such conditions prevail in secluded valleys, 

 anthrax persists among herds. 



Aside from these limitations to specific conditions of the soil, 

 anthrax is a disease of world-wide distribution. It exists in most 

 countries of Europe, in Asia, Africa, Australia, and in our own 

 country in the lower Mississippi Valley, the Gulf States, and in some 

 of the Eastern and Western States. It seems to be gradually spread- 

 ing in this country and occurs in new districts every year. 



Meteorological conditions also have an important share in deter- 

 mining the severity of the disease. On those tracts subject to inun- 

 dations in spring a very hot, dry summer is apt to cause a severe 

 outbreak. The relation which the bacillus bears to these conditions 

 is not positively known. It may be that during and immediately 

 after inundations or in stagnant water the bacilli find enough nourish- 

 ment in the water here and there to multiply and produce an abundant 

 crop of spores, which are subsequently carried, in a dry condition, by 

 the winds during the period of drought and disseminated over the 

 vegetation. Animals feeding upon this vegetation may contract the 

 disease if the spores germinate in the body. 



Another source of the virus, and one regarded by many authorities 

 as perhaps the most important, is the body of an animal which has 

 died of anthrax. It will be remembered that in such bodies the 

 anthrax bacilli are present in enormous numbers, and wherever blood 



