420 



Sir I). Bruce and others. Trypanosome [Feb. 24,. 



Table XVIII. — Comparison of the Percentage of Posterior-nuclear Forms- 

 found among the Short and. Stumpy Varieties of the Trypanosome of the 

 five Wild Glossina morsitans Strains. 



Date. 



Experiment 

 No. 



Animal. 



Percentage among short 

 and stumpy forms. 



1912 



523 



Monkey 



12 -3 



1912 



542 



Dog 



28 -9 



1912 



551 



ji 



12 -8 



1912 



595 



3) 



4-5 



1912 



602 



'3 



4-2 





12 -5 



Comparison of the Human Strain with the Wild-game and Wild Glossina 



morsitans Strains. 



Table XIX. — Average Length of the Trypanosome of the Human, Wild- 

 game, and Wild Glossina morsitans Strains. 



Strain. 



Number of 

 trypanosomes 

 measured. 



Animal. 



In microns. 



Average 

 length. 



Maximum 

 length. 



Minimum 

 length. 



Wild. &. morsitans 



3600 

 2500 

 2500 



Eat 



24 -2 

 22 -6 

 22 -6 



38 -0 

 35 -0 

 35 -0 



15 -0 

 15 -0 

 15 -0 



It is remarkable that the Wild-game strains and the Wild Glossina morsitans 

 strains should come out exactly alike. Why the Human strains differ to 

 some extent from the other two cannot at present be explained. 



The curves of the Wild-game strains and the Wild Glossina morsitans strains 

 are so similar that there can be little doubt the same species of trypanosome 

 is being dealt with. The Human strain differs so much, that the suspicion 

 must present itself that in some way more than one species is being dealt 

 with. The three Human strains which differ most from the Wild-game and 

 Wild Glossina morsitans type are Stephens and Fantham's case of Armstrong, 

 in Liverpool ; Strain I, Mkanyanga ; and Strain III, Chituluka. On examin- 

 ing these three strains, however, from every possible point of view, nothing, 

 except the difference in the type of curve, can be found to justify this 

 suspicion. 



