H. infantum and H. tropica. However, I feel bound to say here that there is too great a tendency at present to cultivate these parasites in test-tubes; these experiments are undoubtedly highly interesting, yet they will not give us the clue as to how the parasites are transmitted from man to man. Feeding experiments with blood-sucking insects in the case of these Herpetomonads are very difficult and tedious, owing to the fact that unless a very good case is selected it is almost impossible to follow one or two developing parasites in the guts of blood-sucking insects. Further, such experiments must be carried out with great precision, and the observer must possess a good working knowledge of the many harmless gut flagellates which occur in nearly every insect. So far as I am aware, no attempts have been made to discover the transmitting agent of H. infantum or H. tropica.
Discussion.
Dr. Sambon said that he wished to express his very high appreciation of Captain Patton's work on kala-azar. Captain Patton had pointed out that the cell-enclosed "Leishman-Donovan bodies" became numerous in the peripheral blood of kala-azar patients in the later stages of the disease, and he had shown by feeding experiments that in the mid-gut of the rounded bed-bug (Cimex rotundatus) they assumed the flagellate form obtained by Major Leonard Rogers in artificial culture media. Furthermore, he had endeavoured to work out the entire life-history of the parasite, not only by following its development in the bed-bug, but also by studying allied organisms in other insects.
The slow rate of the bed-bug's dispersion and the
