Page:Transactions of the Royal Society of Tropical Medicine and Hygiene, volume 2 (3).djvu/16

 forms which, obviously, could not be looked upon as encysted. The oval forms were, no doubt, transition forms between the round and long flagellate forms. The round forms did not present the characteristic capsule of encysted forms.

Dr. Sambon maintained that the most important stages in the sporogony of the Trypanosominae had so far escaped the observation, not only of Captain Patton, but of most investigators, notwithstanding that in closely allied groups Schaudinn had traced them in a masterly way. However, certain stages had been observed separately in one or other species. Thus, a number of investigators — such as Prowazek, Liihe, Minchin, &c. — had described a marked trimorphism in several species. He (Dr. Sambon) had seen it himself most evidently in Trypanosoma gam- biense. Indeed, he had been the first to describe differentiated sporonts in T. gambiense, not from the gut of the fly, but from the peripheral blood of man. Conjugation forms had been seen by Prowazek in T. lewisi within the mid-gut of the rat-louse {Hamatopinus spinulosus), and the same interpretation might be given, he believed, to the kala-azar parasites described by Major Leishman, as "splitting off a thin spirillum-like form by unequal longitudinal division."

The ookinete after encystment — true encystment indicated in stained specimens by the numerous pink granules which beset the capsule — had been described by Prowazek in Herpetonionan miiscce, by Minchin in Trypanosoma grayi, and by Flu in Crithidia melophagia. Both Prowazek and Flu had found these encysted forms in the ovaries of the very different flies they had examined, and thus indicated the great probability of hereditary transmission for the respective parasites. This mode of transmission he (Dr. Sambon) had indicated as early