Page:Transactions of the Royal Society of Tropical Medicine and Hygiene, volume 1.djvu/166

 said as to its being not an artifact, but an important stage in the development of the parasite. It was difficult to say exactly what that fission meant. He had thought that it might have something to do with sexual differentiation, and that in a sort of way the side-bodies might be compared to micro-gametes, but for the present that must be con- sidered very doubtful. Another important point, to which the President called attention some time ago, was the simi- larity of the kala-azar parasite and the organism seen in Oriental sore. The parasites were so exactly a,like morpho- logically that it was more than possible that there was some connection between them ; and he believed that the suggestion of Sir Patrick Manson was a true statement of fact. Possibly the explanation was to be found in the intervention of a host belonging to the lower mammalia. In animals, parasites often attacked different anatomical structures to what they did in man, and produced altered effects, so much so that pathologists were now divided into two camps : one of which believed that a parasite in man was distinct from the same parasite as seen in an animal ; the other, that it was in every way identical. That was the case, for instance, with tuberculosis, malaria, and many other diseases ; the parasites were specifically distinct, and it was correct to give them different names. But it was quite possible that in course of time one species might pass into the other, and that the tubercle bacillus which came from the cow might be the progenitor of the one which had now become special to man. That was perhaps also the state of affairs in diphtheria and many other diseases ; and he thought as the same parasite often affected different habits in man and in animals, that fact might throw some light on kala-azar and Oriental sore.

Dr. Sandwith said the suggestion of Colonel Leishman, which he was glad to know emanated from the Egyptian