In addition, they are known carriers of some of the worst and most dreaded diseases, as bubonic plague, trichinosis, and septic pneumonia; while there is little doubt that they spread scarlet fever, typhoid, diphtheria, and other contagious maladies. Bubonic plague is mainly dependent upon rats for its dissemination and has been carried by them to more than fifty countries, including the United States. In India more than two million people have died in one year from this rat-conveyed disease. Although rats are abhorred by man, yet they have been for ages so closely associated with most of his activities that they have long had their place in Old World literature. Among other instances, many readers will recall Victor Hugo’s gruesome account of Jean Valjean’s fight with the rats in the sewers of Paris. In England and on the continent rat catching has been a regular trade and dogs have been specially bred for use in their pursuit. Rats are loathsome vermin which civilized man should eliminate with the other evils of his semi-barbaric days which he is leaving behind. One might still wish that in many places a modern “Pied Piper of Hamelin” would appear and rid the people of these pests. This is not necessary, however, if the public will cease to take their presence as a matter of course. Their exclusion from buildings and destruction are merely matters of good housekeeping, both personal and communal. Rats can be banished by removing or destroying trash heaps and similar harboring places and by the simple expedient of rat-proofing buildings, especially dwellings, granaries, warehouses, and other places where food supplies are stored. These precautionary measures should be supplemented by trapping or poisoning in open places. Campaigns of this kind can be fully successful only when engaged in by the community at large. The returns from the investment for such a purpose will be large, not only in the vast money values of property saved, but in the reduction of the death rate and in the great improvement of the public health. THE HOUSE MOUSE (Mus musculus) (_For illustration, see page 531_) The familiar house mouse is of Old World origin and may be distinguished from most of our native mice by its proportionately slenderer body, long hairless tail, and the nearly uniform color on the upper and under parts of the body. Like the house rat, wandering an alien from its original home in Asia, and transported by ship and by inland commerce, it has gained permanent foothold and thrives in lands of the most diverse climatic conditions, except those of the frigid polar regions.