496 Sir D. Bruce and others. Description of a 



Mr. Shilston also made a large number of measurements of this strain. 

 One of his charts gives the percentages in respect to length of 400 trypano- 

 somes occurring in the mule, dog, and guinea-pig, the measurements 

 being made at varying periods of the disease. This chart is reproduced on 

 p. 495. 



In a previous paper* a curve will be found representing the percentages 

 in respect to length of 200 individuals of the original strain of T. brucei, 

 measured from old Zululand preparations which had been made in 1896 and 

 were still extant. The numbers making up these two curves are doubtless 

 small, but they are fairly comparable. 



Chart 2.— Curve representing the Distribution, by Percentages, in respect to Length, of 

 200 Individuals of T. brucei, Zululand Strain, 1896. 



18 

 17 

 16 

 15 

 14 

 13 

 12 



g «• 

 2 8 



n- r 



6 

 5 

 4 

 3 

 2 

 1 



Microns 



13|14|15|16 



17|18 



19 



20 



21 1 22 



23 



24|25 



2G 



27 



23 



29 



50 



31 



32 



33 



34 



35 

























































































































































































































































































































































































































































































\ 

















































































































































































f 



































































































































































































































Now although too much weight must not be placed on this comparison, 

 still it must be confessed that the two curves are remarkably alike, and 

 afford a strong argument that Shilston recovered from the Somkele district 

 of Zululand the same species of trypanosome which had been discovered 

 there in 1894. Again, when the action of these two strains on various 

 animals is compared, the same likeness is seen. 



Bruce's 1896 strain killed two horses in 30 and 49 days.f Shilston's 



* 'Boy. Soc. Proc.,' B, vol. 83 (1910). 



t ' Further Keport on the Tsetse-fly Disease, or Nagana, in Zululand,' 1896. 



