Page:Popular Science Monthly Volume 51.djvu/73

Rh typhus was recognized as a distinct disease, and distinguished from the other pests of the medical profession.

During the sixteenth and seventeenth centuries the bubonic plague seems to have prevailed as an endemic disease in Europe.

There was scarcely a year during these two centuries that this disease did not assume alarming proportions at some place on that continent. The last visitation in England is known as the Great Plague in London, which occurred in 1665. This has been very graphically described by De Foe, and has been the basis of the thrilling story by Ainsworth entitled Old St. Paul. During the last quarter of the seventeenth century the plague seems to have gradually receded toward the East.

During the eighteenth century it repeatedly threatened to extend over Europe, but seldom reached farther than Turkey and the immediately adjacent territory to the north. However, there were as many as eighteen distinct and severe epidemics in Constantinople during that time.

Up to 1841 the plague occasionally became epidemic in the Balkan Peninsula, and there was an outbreak in the province of Astrakhan in the winter of 1878-'79. Since the last-mentioned years it has not appeared in Europe, but has continued in certain parts of Asia. In 1894, just before the beginning of the Chinese-Japanese War, it appeared in a virulent form at Hong Kong. The Japanese Government sent Kitasato and the French sent Yersin to study this disease according to the latest methods of bacteriological research. Both of these men were eminently qualified for the work of their mission, and independently each soon succeeded in isolating the specific bacillus. It is found in the fæces, in the contents of the swollen glands, and in the blood. It consists of rods with rounded ends, which take stains more markedly at the extremities than in the middle. Sometimes the germ seems to be surrounded with a capsule. In beef tea it grows in chains and forms a viscid deposit on the walls and bottom of the tube. It also grows on blood-serum and agar. On potatoes it does not grow at ordinary temperature and only feebly at 38° C. It shows but little motility and grows most abundantly at the temperature of the body.

The bacillus is pathogenic to guinea pigs, rabbits, rats, and mice, and it is stated that at times of the existence of an epidemic of the plague some of these animals acquire the disease, and it has been suggested that they may act as agents in its spread. In the above-mentioned animals the first symptoms manifest themselves usually within from one to two days after inoculation. The animal becomes apathetic, the eyes are watery, the temperature rises, and death, preceded by convulsive movements, comes on within from two to five days. The tissue around