complete life-cycle of H. lygæi when I had my heavily-infected bugs I might have been able to solve this problem. This emphasizes the importance of studying these seemingly unimportant parasites, and I am sorry to say there are some people who still think it is a waste of time to study such forms, but there is no doubt that a knowledge of their life-cycles is of the utmost importance in helping to explain those of more complex pathogenic protozoa.
I have now shown you that the parasite of kala-azar is a Herpetomonad, and that in its preflagellate stage it may be indistinguishable from a harmless species; this truth is of importance, because in spite of other data the two closely allied human forms—the parasites of infantile splenomegaly and Oriental sore—are still regarded as identical with the parasite of kala-azar. I know at least three closely allied Herpetomonads which are very similar in their preflagellate stages to H. muscæ domesticæ so that this similarity in one stage is of little importance in distinguishing between these species. The parasite of kala-azar should, therefore, be known as H. donovani (Laveran and Mesnil), the parasite of infantile splenomegaly as H. infantum (Nicolle), and the parasite of Oriental sore as H. tropica (Wright), and I would suggest the diseases produced by these parasites should be collectively known as Herpetomoniases.
It is most unfortunate that all attempts to transmit H. donovani to animals have entirely failed; quite recently I inoculated dogs with the parasite, with negative results. It seems to me, therefore, that it will be well-nigh impossible to prove finally that C. rotundatus is the carrier of this dangerous parasite. It is to be hoped, therefore, that exhaustive feeding experiments, similar to those I carried out in Madras, will be conducted with
