126 DISCUSSION
sore is eminently benign. It is known that one attack of Oriental sore confers immunity against further attacks of the same disease. Oriental sore is a disease of camel- using countries. It is said to affect dogs and possibly other animals. May it not be that the virulence of the Leishman body is removed by passage through the camel or some other animal ; or, possibly, by being transmitted by some intermediary other than that which transmits the virulent kala-azar ? If this be so, we have at hand a vaccine against kala-azar. This idea is worth testing : are those who have had Oriental sore immune as regards kala-azar, and 7)ice versa / "
So far, this important suggestion did not seem to have been taken seriously, and most authors had dis- missed it by stating that it was negatived by the different geographical distribution of the two diseases.
Quite recently, Dr. Nicolle had suggested that the likewise indistinguishable parasite found in the spleen and other organs of children suffering from splenic anaemia in Tunisia should be looked upon also as a distinct species, and called Leishmania infantum; and Dr. Darling had advanced that the same parasite found in two negroes from Martinique and a Chinaman from Canton — all of whom had resided for a longer or shorter period in the Panama Canal zone — should be considered not only as belonging to a distinct species, but to an entirely new genus, and proposed calling it Histioplasma capsulatum.
He did not think they could accept Nicolle's and Darling's suggestions. Nicolle did not give any reason why they should look upon the parasite found in Tunisian children as distinct from that found in the children and adults of other countries, and the morphological differences indicated by Darling, as distinguishing his parasite from that of typical kala-azar, were the very characters
