EEPOET OF THE BTJEEATT OP ANIMAL INDUSTRY. 153 



tines, lungs, heart, and kidneys. The lymphatic glands are purplish 

 instead of a pale pink. When the large intestines are opened they 

 are found covered with these dark spots of blood more or less uni- 

 formly and entirely. Often the contents are covered with clotted 

 blood. Any or all of these may be considered as signs of the disease 

 in its most virulent form. In many outbreaks the early cases do not 

 succumb so rapidly. They grow weaker, lie down much of the time, 

 eat but little, and usually have diarrhea. Most of such cases may 

 linger for weeks, meanwhile scattering the poison in the discharges. 

 The disease may be recognized in these cases as soon as they are ob- 

 served to act suspiciously, and there should be no delay in determin- 

 ing at once the nature of the disease. When the animal has been 

 opened the large intestine should be carefully slit up and examined, 

 beginning with the blind or upper end. There will be seen round- 

 ish, yellow or blackish spots, having an irregular depressed, some- 

 times elevated surface. These spots are ulcers and correspond to dead 

 portions of the mucous membrane, and they are frequently seen from 

 the outside as soon as the animal is opened. Sometimes the mem- 

 brane has been entirely destroyed. 



In order to comprehend fully the reasons for the preventive meas- 

 ures suggested, let us briefly trace the various ways in which hog 

 cholera bacteria may pass from a diseased or dead animal to a 

 healthy one. 



Pigs may become directly infected by feeding on the carcasses of 

 such as have died of the disease, or by feeding on the f eces and urine 

 of sick animals ; or they may become indirectly infected by feeding 

 upon material in which hog cholera bacteria are accidentally present 

 and in which they have multiplied. This would include milk, water, 

 and perhaps most vegetables in a boiled condition. It has been 

 pointed out in preceding pages that hog cholera bacteria multiply 

 very abundantly in milk, especially in warm weather; that they re- 

 main alive in water for months, and that they multiply upon boiled 

 potato. It has also been shown by an extended series of experiments 

 that they may remain alive in the soil for from one to four months. 

 The sources of infection are thus numerous enough. It has likewise 

 been demonstrated that these disease germs will resist drying for 

 several months. Hence dried discharges of the sick, or the dried 

 bodies of dead animals, are still infectious. 



The channel of infection is, in most cases, the food and drink. 



This has been frequently demonstrated and emphasized in forego- 

 ing reports. 



The food, after leaving the stomach, passes in a liquid condition 

 through the small intestine, so that this never seems filled ; in fact, 

 its only contents is a coating of semi-liquid matter over the mucous 

 membrane. It passes through the small intestine quite rapidly, but 

 on reaching the large intestine the undigested remains become more 

 consistent, because the liquid is re-absorbed and is kept here for 

 some time. The bacteria, if not destroyed by the gastric juice, pass 

 quickly through the small intestine, but in the large intestine they 

 begin to multiply and attack the mucous membrane, which they de- 

 stroy. Thus the feces or discharges of diseased pigs, wherever de- 

 posited, scatter larger or smaller quantities of the virus in this way, 

 completing the circle of infection. 



In order to prevent the remaining healthy animals in an infected 

 herd from taking the disease, the following measures are suggested 



