SWINE FEVER 189 



perature of summer, and retains its vitality for more than fifteen days 

 in sterilized water. 



Biological Characters. On Gelatine Plates the surface colonies 

 are spread out flat with round or irregular borders ; the deeper colonies 

 are small, almost homogeneous brownish spheres. 



Stab Cultures in Gelatine resemble a nail with a flat top (see Photo- 

 micrograph, Fig. 73.) 



On Agar-Agar Media a greyish-white transparent growth occurs, 

 and in Grape Sugar A gar gas is formed. 

 On Potatoes a yellowish growth occurs. 

 Bouillon becomes cloudy, and a film forms on the surface. 

 Milk remains unchanged, and the reaction alkaline. 

 Neither Indol nor Phenol are formed. 



Pathogenesis. A small quantity of a culture kills rabbits and mice 

 in seven to twelve days with elevation of temperature. The lesions found 

 are enlarged spleen of a dark red colour, and necrotic patches in the 

 liver. The kidneys are inflamed, and the urine contains albumen. The 

 substance of the heart is flabby, and fatty degeneration is present. The 

 mucosa of the small intestine is swollen, and the contents are shiny, and 

 ecchymoses are often present here and in the duodenum. The charac- 

 teristic bacilli are present in small masses in all the organs, mostly in 

 the capillaries and small veins. Injection of the virus into the lungs 

 causes pneumonic changes. Feeding with cultures and inhalation also 

 cause infection. Pigeons are somewhat refractory, but can be affected 

 by large doses. Chickens are not affected even with large quantities of 

 the virus. Swine are somewhat refractory to subcutaneous injections, 

 but by intravenous injection of 1 to 2 c.c., and feeding with cultures, a 

 severe diphtheric inflammation of the stomach and large intestines occurs. 

 In other cases the bacilli are less virulent, especially when obtained 

 from chronic cases of swine fever. The characters of the cultures can, 

 moreover, also vary. The necrosis of the liver is not present in the 

 milder forms of the disease, therefore the changes in the bowel are 

 more pronounced. Abscesses sometimes develop under the skin at the 

 point of inoculation. Swine fever sometimes occurs in devastating 

 epizootics, especially in America, when 90 per cent, of the swine may 

 die. It occurs in an acute or haemorrhagic septicaemic form, killing the 

 animal in a few days ; and in a chronic form, when the disease may last 

 two to four weeks, or even longer. The post-mortem examination of 

 affected animals presents a variety of lesions, which vary according to 

 the severity and length of time the animal has been affected. The 

 following is a summary of lesions observed in cases of swine fever : 



Tumefactions round the head and back, the tongue darkish in colour, 

 and small necrosed patches and ulcers are often present on the lips, 

 gums, and tongue. Along the abdomen numerous dark red-blue 



