I Have been much interested in Professor Nuttall's paper in the April number of Parasitology (this volume, p. 113) and especially in his description of a parasite found by him in blood smears from a buffalo sent to England from British East Africa. He has named this organism Spirochaeta bovis caffris though he is evidently somewhat doubtful as to its nature. I write to say that early in 1909 I received from Captain Hadow one blood smear from a Jackson Hartebeeste which he had shot in the Bahr-El-Ghazal and on the body of which he found G. morsitans in the act of feeding. In this smear I found organisms which answered very closely to those described and figured by Professor Nuttall. They were somewhat smaller, having an average length of 16·5 μ and a breadth of 0·7 μ but presented the same appearance, stained in the same way and in some instances showed the achromatic transverse bands which he mentions. From its shape I mentally termed one variety the buffalo-horn type and I made drawings of the different forms encountered. On April 18th 1909 I sent the slide to Dr Wenyon at the London School of Tropical Medicine with a note directing his attention to these curious parasites and stating that, to me, they looked more like spirochaetes than anything else but that I was unable to classify them. Unfortunately, though my letter was safely delivered, the box containing the slide was never seen again. Dr Wenyon, however, wrote and told me that he had come across similar forms in the blood of big game which had been shot, and recorded his opinion that the forms in question were not blood parasites at all but were derived from the intestine and had been carried into the exit wound by the bullet or by discharges finding their way along the bullet track. One recognised the possibility of such an occurrence and the fallacies to which it might give rise and, on meeting Captain Hadow, I asked him if he remembered where the animal had been shot. To the best of his recollection the bullet had passed through the neck severing the gullet and it is quite possible that in the last throes stomach contents might have regurgitated through the wound of exit. The presence of very thin thread-like spirochaete forms in the film and of some bodies which suggested yeasts made me refrain from publishing any account of the case until I had more evidence regarding Dr Wenyon's hypothesis.