INFECTIOUS DISEASES OF CATTLE. 441 



tious 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 posi- 

 tively known. It may be that during and immediately after inunda- 

 tions or in stagnant water the bacilli find enough nourishment 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 vege- 

 tation. Animals feeding upon this vegetation may contract the dis- 

 ease 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 

 or other body fluids are exposed to the air on the surface of the carcass 

 there the formation of spores will go on in the warm season of the year 

 with great rapidity. It will thus be readily understood how this dis- 

 ease may become stationary in a given locality and appear year after 

 year and even grow in severity if the carcasses of animals which have 

 succumbed to it. are not properly disposed of. These should be buried 

 deeply, so that spore formation may be prevented and no animal have 

 access to them. By exercising this precaution the disease will not be 

 disseminated by flies and other insect pests. 



We have thus two agents at work in maintaining the disease in any 

 locality — the soil and meteorological conditions and the carcasses of 

 animals that have died of the disease. Besides these dangers, which 

 are of immediate consequence to cattle on pastures, the virus may be 

 carried from place to place in hides, hair, wool, hoofs, and horns, and 

 it may be stored in the hay or other fodder from the infected fields and 

 cause an outbreak among stabled animals feeding upon it in winter. 

 In this manner the affection has been introduced into far distant 

 localities. 



How cattle are infected. — We have seen above that the spores of the 

 anthrax bacilli, which correspond in their functions to the seeds of higher 

 plants, and which are the elements that resist the unfavorable conditions 

 in the soil, air, and water longest, are the chief agents of infection. They 

 may be taken into the body with the food and produce disease which 

 begins in the intestinal tract; or they may come in contact with 

 scratches, bites, or other wounds of the skin, the mouth, and tongue, 

 and produce in these situations swellings or carbuncles. From such 

 swelling? the bacilli penetrate into the blood and produce a general 

 disease. 



It has likewise been claimed that the disease may be transmitted by 

 various kinds of insects which carry the bacilli from the sick and inoc- 

 ulate the healthy as they pierce the skin. When infection of the blood 

 takes place from the intestines the carbuncles may be absent. It has 

 already been stated that since the anthrax spores live for several years, 



