Evidence accumulates to show that a number of diseases in animals is due to the same bacillus, which is pathogenic in a large number of different species. In all of them it propagates in the blood and induces a rapidly fatal disease. Amongst these Fowl-cholera was first described by Pasteur. The bacillus was next obtained experimentally by Koch and Gaffky in rabbits by inoculating putrid fluids, the disease being called by them Rabbit-septicsemia. It has further been identified as the infective agent in Swine-plague, of which the two forms, German and American, are probably identical. It has also been recognized in a form of cattle-plague (not Rinderpest). It is an exceedingly virulent agent in mice, the disease in these animals being called Mouse-typnus.

In these various animals the disease may be produced by feeding them with infected material or by inoculation, the latter method having more rapid effects. Thus when administered by the mouth in field mice it causes death in from six to twelve days, whereas subcutaneous inoculation is fatal in from two to four days.

This microbe is further interesting, as it was used by Loefrler for the purpose of stopping the plague of field mice in Thessaly. Food stuffs impregnated with the bacillus were distributed so that the animals should eat them. Pasteur had previously proposed the use of the same microbe to deal with the rabbits in Australia.

The microbe is a short thick rod which stains chiefly at its two ends, leaving a clear space in the middle. This limited staining may cause it to be taken for a micrococcus. It is stained by the ordinary watery solutions of the aniline dyes, but not by Gram's method. It is readily grown on nutrient media.

As above noted, this microbe is pathogenic in a large number of animals. In fowls it produces a condition characterized by htemorrhagic enteritis, and by progressive weakness and torpor. The bacilli are abundant in the evacuations from the bowels. Pasteur has extracted a substance from the cultures which is highly narcotic, inducing in fowls a condition of somnolence and coma.

A vaccine of the bacillus of fowl-cholera was obtained by Pasteur by cultivating it for some time at an elevated temperature.