284 THE BACILLUS OF SWINE ERYSIPELAS 



the liver is congested and the blood very dark in colour. More rarely, a thickening 

 of the walls of the intestine and patches of broncho-pneumonia are present. 



The specific organism is found in the liquid discharges from the bowel, in the 

 spleen, lymphatic glands, bone marrow, and also but in smaller numbers in the 

 blood, liver and kidneys. 



The bacillus of swine erysipelas appears to be frequently present as a 

 saprophyte in the tonsils and intestinal canal of healthy pigs (Olt, Pitt, Over- 

 beck). Pitt found the organism in the intestine in 26 out of 66 and in the 

 tonsil in 28 out of 50 normal animals examined by him. 



SECTION I. EXPERIMENTAL INOCULATION. 

 1. Animals susceptible to the disease. 



Swine, pigeons, mice and rabbits are all susceptible to swine erysipelas 

 but in different degrees. Guinea-pigs are immune. 



Inoculation into the pectoral muscle of a pigeon or into the sub-cutaneous 

 tissue of a mouse is fatal in 3 or 4 days. Babbits are more resistant and to 

 produce a fatal result the virus must be inoculated into a vein. 



When passed through a series of rabbits the virulence of the virus is increased 

 for rabbits but diminished for swine. The first rabbit is inoculated intra-venously 

 with a culture from a pig and the spleen of the first rabbit is used for inoculation 

 of the second and so on. 



On the other hand, the virulence is increased for all susceptible animals by 

 passage through pigeons. 



It is a curious fact that swine are not very susceptible to experimental 

 infection, and even when the virus is inoculated into a vein it seldom leads 

 to a fatal result ; so that to produce the disease in these animals a virus 

 experimentally increased in virulence must be used for inoculation. It is 

 however possible to infect pure bred swine by feeding them on the organs 

 of animals which have died of the disease. 



2. Technique of inoculations. 



The general rules applicable to the inoculation of animals must be observed 

 and special attention given to the following points. The material for inocula- 

 tion may be taken directly from the spleen, lymphatic glands or blood of an 

 animal dead of the disease, though it is better to sow a broth culture with a 

 fragment of the spleen and to inoculate a little of the culture after incubating 

 it for 36-48 hours. 



3. Symptoms and lesions. 



The symptoms have already been detailed. 



The most prominent lesion in experimentally-infected animals is the 

 swelling and softening of the spleen. The organism will be most easily 

 detected in the spleen, bone marrow, tonsils, lymphatic glands and blood, 

 but may also be found in the liver and kidneys. Sections of the lymphatic 

 glands, spleen, liver and kidneys should also be cut. 



SECTION II. MORPHOLOGY. 

 1. Microscopical appearance. 



The micro-organism of swine erysipelas is a small, non-motile bacillus, 

 visible only with difficulty in unstained preparations, and measuring 0'5-1'5/* 

 by 0'2-0'3/ji. In the blood and internal organs it occurs singly, in pairs or 



