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XX] able accident in a Vienna laboratory, in October, 1898, by which fatal plague of a pneumonic type was acquired— in what way is not exactly known— from manipulations with plague cultures goes far to complete the little that was wanting in the chain of evidence that this disease is caused by the introduction of the specific bacillus into the human body. The unintentional experiment, in this instance at all events, was not vitiated by having been made in the presence of a plague epidemic.

There is no reason for supposing that man differs in this respect from the lower animals, many of which are exceedingly susceptible to inoculation. Mice, rats, guineapigs, and rabbits are invariably killed if successfully inoculated from the buboes* of plague patients. They present on dissection characteristic lesions with numerous bacilli in the lymphatic glands, blood, spleen, and other viscera. Guineapigs die in from two to five days after inoculation, mice in from one to three days. Calves and swine are susceptible to inoculation, and so are monkeys and many other animals. In the case of the guineapig, within a few hours of the introduction of the virus a considerable amount of œdema is already apparent around the puncture, and the adjacent gland is perceptibly swollen. At the end of twenty-four hours the animal is very ill; its coat is rough and staring, and it refuses food. Presently it falls on its side and becomes convulsed, one fit following another with increasing frequency as death approaches. If the body is opened immediately after death a rosy-red sanguineous œdema is found at the point of inoculation, with hæmorrhagic inflammatory effusions around the nearest lymphatic gland, which is much swollen and full of bacilli. The intestines are hyperæmic; the adrenals, kidneys, and liver are red and swollen. The much enlarged spleen frequently presents an