Hog cholera bacilli fed to mice disappear from the stomach within 24 hours, but remain and perhaps multiply in the ileum for at least several weeks. They promptly penetrate the mucosa and may be found in the spleen. Bacilli introduced subcutaneously quickly pass into the intestinal tract where they may be found for some weeks. Infected mice may harbor bacilli in the spleen for several months.
Mice possess a relatively high degree of natural resistance towards hog cholera bacilli which gives way to large doses. Disease is probably the result of the invasion of the viscera from the digestive tract following feeding, but the relation between the dose fed and the numbers penetrating the mucosa is a variable one and the conditions favoring such invasion not determined. Contact with mice discharging bacilli failed to cause recognizable invasion of the digestive tract or the viscera.