ON KALA-AZAR 131
were naturally infected ; but, quite recently, Novy had been able to reproduce the infection in dogs in Michigan, U.S.A., where the disease was unknown, and the para- sites he had inoculated were not of canine but of human source, obtained indirectly from Nicolle.
Besides the horse and dog, other animals, both wild and domestic, were probably concerned in the spread and conservancy of kala-azar, and he would point out more especially certain ruminants such as camels, oxen, and sheep. A vague relationship between camels and Oriental sore had already been suggested by Dr. Crombie, and parasites similar to the " Leishman-Donovan bodies," whether pertaining to Surra infection or not, had been seen by Lingard and others in these animals. In sheep, the presence of " Leishman-Donovan bodies " was very clearly indicated, he thought, by the presence of exactly similar bodies as well as flagellated forms in the mid-gut of Melophagus ovinus, a wingless, parasitic fly of the family Hippohoscidce, strictly limited to sheep. The find- ing of similar parasites in a large number of insects belonging to the most sundered groups showed that that kind of organism must also have a wide range of verte- brate hosts, and their possible relationship to already known forms of animal trypanosomiases should not be overlooked.
Another fact to which he was inclined to give much importance was the particular stage reached by the parasite at the time of its transmission from one host to another. Christophers and others had shown that, towards the end of the kala-azar infection, ulcerations usually appeared on the skin and on the intestmal mucosa. The parasites found in these ulcerations were, he would suggest, obviously the forms of a spent in- fection which needed sexual rejuvenation. Inoculated
