628 REPORT OF THE COMMISSIONER OF AGRICULTURE. 



sterile. It was presumed that the liver would contain the largest 

 number, inasmuch as the portal circulation received its blood from 

 the seat of the disease. This assumption was confirmed by the very 

 abundant colonies surrounding a piece of liver tissue which had been 

 dropped into a tube of nutrient gelatine. 



In order to make certain of the pathogenic powers of the cultures 

 obtained from this case of feeding the tube culture from the liver 

 was used to infect two rabbits. The skin on the inner aspect of one 

 thigh was carefully shorn and disinfected with .1 per cent, corrosive 

 sublimate. An incision was made through the skin, and with a loop 

 dipped in the surface growth of the culture a minute quantity was 

 introduced into this pocket. The larger of the two rabbits was found 

 dead on the fifth day. The lesions were briefly as follows: 



Slight amount of pus at the place of inoculation. Neighboring inguinal glands 

 enlarged and infiltrated with blood throughout. Surrounding vessels much injected 

 and very tortuous. Liver very friable, spleen dark and enlarged; both dotted with 

 points and stellate spots of coagulation necrosis, especially numerous on the caudal 

 surface of the liver. Both organs contained the bacteria of hog-cholera in large 

 numbers. Lungs deeply congested, perhaps hypostatic. A small number of ecchy- 

 moses beneath pleura; very few bacteria in kidneys and heart's blood. 



The second rabbit was found dead on the sixth day. The lesions 

 were the same, if we except the more pronounced coagulation necrosis 

 in the liver (Plate VI, Fig. 1) and its absence in the spleen. The bac- 

 teria of hog-cholera were distributd as above; very abundant in spleen 

 and liver; lungs normal. 



Gelatine-tube cultures from spleen and liver of these rabbits con- 

 firmed the microscopic examination. Liquid cultures from the blood 

 contained the motile bacteria, which had formed a brittle surface 

 membrane on the second day. 



• Differential characters of the hog-cholera bacterium from Ne- 

 braska. — The bacterium,' when stained on cover-glass preparations 

 from the spleen and other viscera, closely resembles the one found in 

 the disease prevalent in the East, so that it is impossible to distin- 

 guish them m this way. Both stain well in an aqueous solution of 

 methyl- violet in from two to five minutes, and show a well-stained 

 narrow periphery around a jDale center. This may be due to the 

 presence of a dense envelope obstructing the inward movement of 

 the coloring matter. In the last report an opinion was expressed that 

 it might suggest the presence of an endogenous spore, but that the 

 other evidence did not seem to warrant such a view. The experi- 

 ments of the present year have not changed these views. The illus- 

 trations given in the last report apply equally well to the microbe 

 from Nebraska. 



A few minor differences revealed in the various culture media indi- 

 cated that the two microbes were not alike in every way, and brought 

 up the very interesting question of the variation of species of bacteria 

 and the influence of such variation on the severity of epidemics. 



The first difference was observed in liquid cultures. Within 

 twenty-four hours after inoculation from the spleen or blood the 

 culture liquid became turbid, and upon its surface a complete mem- 

 brane was present in nearly every case. This whitish membrane is 

 not homogeneous, but made up of patches of varying thickness, and 

 when shaken, slowly settles to the bottom in lumps and flocculi. The 

 microbe of Eastern outbreaks does not form a membrane within sev- 

 eral days after inoculation, and then only_ when the tube remains 

 perfectly quiet. It appears as a whitish ring attached to the glass, 



