612 REPORT OP THE COMMISSIONER OF AGRICULTURE. 



The bacterium of hog-cholera has therefore the power of multiply- 

 ing ill what is practically a vacuum, but this power is limited. The 

 other microbes failed to show any signs of growth whatever. They 

 were purely aerobic. The bacterium of hog-cholera may therefore 

 be regarded as holding a place midway between those microbes which 

 seem to thrive better without air — anaerobic — and those that fail to 

 grow without it. 



That no spores were found in these bulbs may be inferred from the 

 following experiment: One of the tubes kept sealed for a month was 

 opened and a number of culture tubes inoculated therefrom. They 

 were then exposed to a temperature of 58° C. for 15, 20, 25, and 30 

 minutes. All remained sterile. One, inoculated, without being 

 subsequently heated, was turbid with the specific bacterium next day, 

 indicating that it was still alive in the bulb when the latter was 

 opened. 



MODES OF INFECTION. 



(a) By tvay of the digestive tract. — In at least 90 per cent, of 

 swine a very severe form of hog-cholera may be induced by feed- 

 ing to them the viscera of animals which have died of the disease. 

 The lesions produced are exceedingly severe. The mucous membrane 

 of the large intestine is extensively ulcerated or completely necrosed. 

 In animals which have contracted the disease in the ordinary way in 

 infected pens the ulceration of the large intestine, at times very se- 

 vere, usually stops abruptly at the ileo-ceecal valve. When this is 

 slit up, the mucosa belonging to the small intestine up to the free 

 border of the valve is in the great majority of cases normal, while the 

 mucosa of that surface of the valve facing the caecum may be exten- 

 sively ulcerated. In many animals fed with infectious matter the 

 ulceration involves the entire ileum . This is well illustrated by the 

 following cases: 



January 8, 1886. — Pig No. 165 was fed with the viscera of two pigs which had died 

 of hog-cholera. It was found dead January 26, after manifesting no marked symp- 

 toms of disease except a tendency to lie quietly in its pen. On examination the sub- 

 cutaneous fat was found diffusely reddened. There was a slight peritonitis, indicated 

 by a considerable quantity of straw-colored effusion and some fibrinous stringy de- 

 posits. There were also a few local excrescences on the small intestine, due to the 

 irritation of echinorhynchi. Spleen somewiiat enlarged ; on its surface a few 

 bright red punctiform elevations. Right heart distended with a clot. Local hepa- 

 tizations in lungs, probably caused by lung worms, wliich were very numerous. 

 Stomach but slightly reddened. A number of ulcers in the duodenum, the mucosa 

 of which was reddened. The mucosa of the ileum for 1| feet from valve was com- 

 pletely necrosed, the walls tliickened, and the serosa of this portion dotted with ec- 

 chymoses. Beyond this portion, near the jejunum, there were scattered ulcera- 

 tions on a deeply congested membrane for 6 or 7 feet. The entire length of the 

 large intestine was covered with duly yellowish ulcerations varying in diameter 

 from a pin's head to nearly an incii. The mucosa itself was very deeply congested 

 in the caecum and colon only and the walls much thickened. Ascarides and eclii- 

 norhynchi numerous in small intestines. The liver attached to diaphragm in several 

 places by wliitish exudate. 



A tube of meat infusion with peptone inoculated from the spleen of this animal 

 was found to be a pure culture of the motile bacterium of hog-cholera. Line 

 cultures on gelatine plates confirmed tlie microscopic examination. A tube of nu- 

 tritive gelatine inoculated from the spleen at the same time contained in each needle 

 track, several days later, from 10 to 15 colonies of the same bacterium. Two cover- 

 glass preparations revealed no bacteria. This fact, combined with the small num- 

 ber of colonies in the tube culture, gave evidence of the small number of germs in 

 the spleen tissue. Inoculations on mice and giunea-pigs gave substantially the 

 same results as those obtained last year. 



No. 159 was fed with the viscera of No. 165 on January 28. February 5^ its 

 eyes were sore and nearly closed ; it was quite weak. It died on the following day, 



