Susceptibility. Pathogenesis. 65 



them with the erysipeloids of man in a special class (Erysipelotriches: Erysipelothrix 

 porci, E. erysipeloides and E. muriseptiea). This conception, however, appears to have 

 insufficient foundation as the morphological differences are only slight and since 

 the variance in the rapidity of their growth in artificial media is pronounced. (The 

 quickest growth is obtained with the mouse bacillus; less rapid is the Bac. erysipe- 

 loides, while the slowest is the erysipelas bacillus). Stickdorn observed similar dif- 

 ferences in the erysipelas bacillus after passage through mice and pigeons in 

 spite of the fact that serum examination showed no differences in the strains or 

 species; and Overreck also found that the erysipelas bacillus and the mouse bacil- 

 lus agglutinate practically uniformly (1:2000 to 4000) when the organism of the one 

 is applied to the immune serum of the other. 



Schipp found a bacillus in the blood of a chicken which was identical with 

 the erysipelas bacillus. On that particular farm many animals died in a short 

 time and the autopsies revealed principally an enteritis and a parenchymatous de- 

 generation of the heart muscle. The same author also isolated a bacillus from the 

 spleen of a cow which died with symptoms of anthrax and which on autopsy re- 

 vealed only petechiae on the serous membranes and on the heart. This organism 

 corresponded morphologically and culturally with the erysipelas bacillus. It was, 

 however, pathogenic for field mice and was not influenced by erysipelas eera. As 

 a secondary finding erysipelas bacilli were also obtained from a cow which died 

 from vaginal diphteria and septic metritis, and by Hauser in diphtheritic mem- 

 branes of chickens. 



Susceptibility. Hogs are particularly susceptible to nat- 

 ural infection between the ages of three months and one year. 

 Sucking pigs manifest a higher resistance while animals over 

 one year old become only exceptionally affected as they have 

 probably acquired immunity during their earlier life. 



According to Lydtin the English breeds are more suscep- 

 tible, particularly the Suffolk and Poland China breeds, while 

 Yorkshires are less susceptible. The German hogs are highly 

 resistant, while the Hungarian breeds (Mangalicza) occupy a 

 middle position in the order of susceptibility. The disease usu- 

 ally rages more severely among imported hogs than in the 

 hogs which have been raised in the infected locality. The 

 disease has not yet been established in wild hogs. 



Pathogenesis. The entrance of highly virulent erysipelas 

 bacilli in large quantities into the intestinal canal of healthy 

 hogs will reduce the normal resistance of the animals, and on 

 the other hand the entrance of such bacilli will promote the 

 pathogenic action of such bacilli as were already present in 

 the intestinal canal, by their weakening influences upon the 

 system. Their penetration into the depth of the intestinal 

 mucous membrane is facilitated by injuries through intestinal 

 parasites (strongylids, echinorhynchus gigas), whereupon they 

 multiply in the lymph spaces of the tissues, enter the lymph 

 glands and finally the blood circulation. The bacilli which enter 

 the blood in this manner or through injuries in the skm will 

 continue to multiply there, and then they accumulate m large 

 masses in certain blood vessels, producing weakening of the 

 vessel walls, serous transudations and small hemorrhages 

 probably by the action of the metabolic products. The 

 reddening of the thinner parts of the skin may be 

 traced to this cause, -whereas the necrosis of the skin which 

 occasionally occurs is the result of the obstruction of the blood 



