One of the strongest proofs that leprosy is at least feebly contagious is that based on the disappearance of the disease following isolation of the lepers. The best instance is that of Europe, in the thirteenth and fourteenth centuries, where, with 20,000 leper asylums for isolation, the disease disappeared by the fifteenth century. In Norway, there were 2833 cases in 1856, while in 1907, there were only 438 left. At the end of 1913 there were only 285 cases, 181 of these being interned and 104 in their own homes. The reduction is attributed to isolation. This might have occurred without isolation because Hansen in investigating the descendants of 160 known Norwegian lepers, who immigrated to the North-western States of America, was unable to find trace of a single leper among their descendants. This and other facts militate against the views that leprosy may be inherited and the idea is generally held that if a child be taken away from its leprous surroundings after birth there is little or no likelihood of its developing leprosy. Again, it is a well-recognized fact that leprosy is more than twice as common among men than among women. It is probable that the greater opportunity for contact with lepers by man is the explanation of the greater frequency. _Views as to Mode of Transmission._—It may be stated that nothing definite is known. There has been an idea that itch mites might transmit the disease but no proof has been advanced. Lebouf found leprosy bacilli in the stomachs of flies, which had been feeding on leprotic ulcerations, and did not find acid-fast rods in flies which had fed on persons with nerve leprosy or upon those not showing open lesions. He thinks that flies may deposit faeces containing bacilli about the nasal orifices or upon wounds of well persons, bringing about thereby their infection. Skelton was unable to find evidences of leprosy bacilli in bedbugs living in the beds of lepers. Paldrock also was unable to find any evidence of leprosy bacilli in bedbugs a few hours after feeding on leprous tissue, but did find acid-fast rods in cockroaches which had fed on leprosy nodules, even fourteen days after the feeding. A. J. Smith fed bedbugs on Duval’s organism and recovered acid-fast bacilli for considerable periods. The question arises, however, as to the significance of Duval’s bacillus for leprosy. Acid-fast bacilli have been reported from head lice and mosquitoes, when the insects have been feeding on leprous tissue, but little or no evidence of any multiplication has been obtained. For many years Jonathan Hutchinson insisted that leprosy was caused by the eating of imperfectly cured or decomposing fish, a view which now has no supporters.