58 



Trypanosome Diseases of Domestic Animals in Nyasaland. 

 I. — Trypanosoma simiae, sp. nov. Part III. 



By Surgeon -General Sir David Bruce, C.B., F.R.S., A.M.S., Majors David 

 Harvey and A. E. Hamerton, D.S.O., B.A.M.C., and Lady Bruce, B.B.C. 



(Scientific Commission of the Royal Society, Nyasaland, 1913.) 

 (Received June 9, — Read June 12, 1913.) 

 [Plates 6-8.] 



Introduction. 



In previous papers* the morphology of Trypanosoma simice and its action on 

 animals have been described. In this it is intended to give an account of 

 its development in Glossina morsitans. 



Before entering, however, into the details of this particular development, 

 it may be of interest to take a general survey of the various modes of 

 development which take place in the different groups of trypanosomes. It 

 may then be laid down that there is a well marked separate and characteristic 

 mode of development in each of the three main groups of trypanosomes : — 



In the first group — the T. bnccei group — which includes T. bmcei, 

 T. gambiense, T. evansi (?), and T. equiperdum (?), the parasites develop — at 

 least in the first two named species — at first through the whole length of the 

 intestinal tract, excluding the proboscis, and eventually reach the salivary 

 glands, where forms resembling those found in the blood of animals are 

 developed, and these alone constitute the infective stage. 



In the second group — the T. pecorum group — which includes T. pecorum 

 and T. simice, the development takes place in the intestinal traet, including 

 the labial cavity of the proboscis, and afterwards the trypanosomes reach the 

 hypopharynx, or termination of the salivary duct in the proboscis. Here 

 they revert to the original blood form and become infective. In this group 

 trypanosomes are never found in the salivary glands, and no blood forms or 

 infective forms are developed until the hypopharynx is reached. 



In the third group — the T. vivax group — which includes T. vivax, 

 T. uniforme, and T. caprw, the initial stages of the development take place in 

 the labial cavity of the proboscis alone ; later the hypopharynx is invaded, 

 where again blood forms are developed, which again constitute the only 

 infective forms. Here also there is no invasion of the salivary glands, and, 

 in addition, no development takes place in the intestinal canal. 



* ' Eoy. Soc. Proc.,' 1912, B, vol. 85, and 1913, B, vol. 86. 



