The way in which the disease spread from Yunnan has been quite clearly established. Along the Tonkin frontier, throughout the provinces of Quan-si and Yunnan, the Chinese maintain a large number of military posts. Mule supply-trains for these posts passed from province to province over the difficult mountain paths. The mule-drivers were natives of Yunnan. In 1892 the plague existed in Yunnan, and it was in the summer of 1893 that the disease appeared at Long-Cheou in Quansi among the Yunnan mule-drivers. These drivers arriving at the post of Lieng-Cheng, after one of their journeys from Yunnan, repaired to the city of Long-Cheou, about ten miles distant. During their sojourn in this city the muleteers developed the first known cases of the plague. From these men the disease spread throughout the city and to the neighboring posts and villages. From Long-Cheou the plague descended the Canton River and reached Naning-Phu. From thence it followed overland to the seaport Pakhoi, some hundred and fifty miles distant. A few months later, in February, 1894, it reached Canton, either by descending the river from Naning-Phu or by boat from Pakhoi. That the plague at Canton, in 1894, had not lost any of its old-time destructiveness is seen in the fact that it is estimated to have caused not less than one hundred thousand deaths in Canton in the short space of two months. From Canton the plague spread to Hong Kong in April, 1894. It was during the existence of this epidemic that the first bacteriological studies of the disease were made and resulted in the discovery of the plague bacillus. In the fall of 1894, the disease died out in Hong Kong, but it reappeared in 1895 and 1896. Considering the fact that Hong Kong is one of the most important maritime centers, it is not surprising to find that in the spring of 1896 the plague was carried by shipping to the Island of Formosa. It is quite certain that about the same time the plague was carried from Hong Kong to Bombay. At all events, the existence of this disease was recognized in Bombay in September, 1896, by Doctor Viegas. Previous to this date, the mortality in Bombay was abnormally high, undoubtedly due to the very unsanitary condition of the overcrowded city.