TRYPANOSOMIASES OF RHODESIA. I37 



(b) The shape and position of the various elements. 



(c) The festooning of the unchilating membrane, and the 

 presence or absence of a free portion of flagelhim. 



(d) The presence of vacuoles and chromatoid granules, etc. 



Such details would appear to be of purely academic interest ; 

 nevertheless, practical issues of the greatest importance to this 

 country have arisen from them ; for this reason I refer to them 

 at some length. 



It will be remembered that in the year 1902 Button and 

 Todd, during their investigation upon human trypanosomiasis, 

 encountered in horses in Gambia a trypanosome and distinguished 

 three forms of the parasite, namely — 



(i) "Tadpole forms," 11 m. to 13 m. long by 0.8 m. to 

 I m. wide. 



(2) " Stumpy forms," the body of which was short and 

 squat. 16 m. to 19 m. long by 3.5 m. wide. Free flagellum 

 short. 



(3) " Long forms," 26 m. to 30 m. long by 1.6 m. to 2 m. 

 wude, with a long free flagellum. 



Later, in 1908, INIontgomery and Kinghorn announced that 

 they had found in cattle near Broken Hill an identical parasite. 



This discovery stimulated careful study into the animal try- 

 panosomiases of South Africa, with the result that trypanosomes 

 of dimorphic type were found in Chai-Chai and Zululand by 

 Theiler, Portuguese East Africa by Connacher and Jowett, and 

 Southern Rhodesia by Bevan, but having slight features of dif- 

 ference from those described by Alontgomery and Kinghorn. 

 The most marked difiference was the absence of the long flagellated 

 form, and this circumstance gave rise to considerable controversy 

 ibetween the various schools, some authorities maintaining that 

 the original disease encountered 'by the Liverpool observers was 

 caused by a multiplicity of parasites rather than by one assuming 

 two types. It was found that the trypanosome of cattle in 

 Southern Rhodesia showed neither the very long form with free 

 flagellum nor yet the very small organism described as " tad- 

 pole " forms. It differed also in the last respect from that found 

 by Theiler and Jowett. But while experimentally endeavouring 

 to make a comparison between the- parasite of Broken Hill and 

 Southern Rhodesian cattle, a result Avas obtained which threw 

 a new light on the subject. 



The circumstances were briefly as follows : Six fat-tail sheep 

 at Broken Hill were inoculated in February from a cow dying 

 of typical trypanosomiasis, and were sent by rail to Salisbury. 

 These animals all reacted, but no trypanosome with undoubted 

 free flagellum was ever encountered in any of them. From 

 isheep No. 2 a white rat was inoculated. Three days later try- 

 panosomes were found in the blood, of the long free flagellated 

 variety, in apparently pure culture. These were at first sus- 

 pected to be Tr. bnicci or Tr. IciOisi, but this was disproved, 

 for day by day as the infection progressed the long forms with 



