128 Swine Plague. 



not produce any perceptible symptonis. After intraperitoneal 

 infection an acute croupous diphtheritic enteritis develops. 

 Vigorous hogs cannot be infected fatally by feeding (Gniichtel 

 succeeded in doing so by weakening the pig by continued 

 cooling) . 



According to Ostertag it is possible to produce the so called chrome swine 

 plague, or the indulent pneumonia of entirely chronic catarrhal nature, which charac- 

 terizes this disease, by inhalation of pathologic lung substance as well as with pure 

 cultures of the ovoid bacterium. However, the limited number of experiments do 

 not appear suflSciently conclusive proof for Ostertag 's contention, inasmuch as 

 other authors always produced by inhalation an acute form of necrotic pneumonia 

 if any disease at all. 



Toxins. Novy isolated from cultures of the bacillus suisepticus 

 a basic substance which he named ' ' Susotoxin, ' ' and which in a watery 

 solution in quantities of 0.125 to 0.25 cc. subeutaneously injected into 

 rabbits produced death in 36 hours. Schweinitz isolated from the 

 cultures a toxin and an albumose which he named "Siiplagotoxine" 

 and " Suplagoalbumin. " Filtrates of fresh bouillon culture, if free 

 from bacteria, are not toxic. On the other hand, killed masses of 

 bacteria produce a toxic action on small test animals. (Guinea pigs 

 are destroyed by 8 to' 10 mg. of killed bacteria [ Voges] ) . Klett & Braun. 

 could by their method demonstrate toxins in large quantities in the 

 filtrates of cultures which produced the characteristic symptoms of 

 cholera in pigeons and chickens, viz., somnolence and intoxication. At 

 the same time the toxicity of the cultures did not run parallel with 

 their virulence (see page 137). According to Beck & Koske fresh 

 filtrates of cultures produce a temporary rise in temperature while 

 killed cultures as well as filtrates of old cultures are very toxic. 

 McFadyean succeeded in extracting from the bacterial cells a filterable 

 poison which was found to be very toxic for rabbits, guinea pigs and 

 mice. 



Natural infection. The experience that pure swine plague 

 occurs usually in a sporadic form or only in a limited enzootic 

 extension indicates that the transmission from animal to ani- 

 mal has only an insignificant part. On the other hand, the fact 

 that bacteria which correspond with the true swine plague 

 organism in all their characteristics, are present in the soil and 

 accordingly also in the food and drinking water as well as in 

 the air passages and intestinal canal of healthy hogs proves 

 that the development of the disease is associated with these 

 facultative pathogenic bacteria. It may be accepted as highly 

 probable that, in a similar way as in the other diseases of 

 the hemorrhage septicemia group, the usually harmless habi- 

 tants of the hog produce a pathogenic action under certain 

 conditions, which are unknown at the present time. It is possi- 

 ble that the bacteria attain a higher virulence before entering 

 the animal body so that they are capable of attacking the 

 normal tissues of the animal. However, it probably happens 

 more frequently that the normal resistance of the organism is 

 diminished by various weakening influences, so that now even 

 the less virulent bacteria may exert a pathogenic action. Lig- 



