The rats are undoubtedly attacked with plague before and during its prevalence among human beings, and they play an important part in the spread of its infection. In Kumaon this rat plague was observed by the people, and was recognized as a forerunner of the plague. The _Times of India_, September 30th, 1896, contains the following:—“It was known more than a month ago to all the people of Mandavi and to all the municipal sweepers in the district that the rats were dying in thousands all over the districts. They were found dead and dying almost everywhere, and in places where dead rats were never found before.” In Bombay an instance has been reported of a man trampling with bare foot on a rat which was seen slowly passing in a room and getting attacked by the plague soon after. Pigs, dogs, snakes, and jackals are said to be also affected by the plague. It will be seen that flesh-eating animals are the sufferers, due evidently to their eating plague flesh. Snakes swallow rats, and rats become infected by consumption of poisoned material or from infected soil or by their cannibal habit. Like other diseases due to a specific germ, the infection of plague may be caught from various sources such as the following—(_a_) By means of breath. Plague dust and dirt are very potent infective agents. A man getting a whiff of dust from the floor of a room in which there is a plague patient blown into his face may get the infection. Sweepers and others engaged in conservancy are, therefore, easily attacked. (_b_) By food or drink. Grain adultered with sand or earth infected by rats may be a source of infection. Food may also be infected by flies or diseased rats (_c_) By direct inoculation through any abrasion in the skin or mucous membrane. People with bare feet are, therefore, more liable to catch the infection. The infection may be spread by infected linen, bedding, furniture and fomites. The discharge from buboes contains the germs, and is, therefore, highly poisonous. The fæces, the urine, the sputum, the fur on the tongue are also infective. If the theory be true that the poison attaches itself to the soil, then persons living on ground-floor are more liable to the infection, and a floating population less so. Dust laden with germs is the principal agent in the diffusion of plague as that of any other germ disease. Professor Aoyama of Tokyo, whilst making a _post-mortem_ examination, scratched the left third finger and was attacked with the plague, also Dr. Ishigami, assistant to Kitasato. _NATURE OF AN EPIDEMIC._