causing Disease in Man in Nyasaland. 



127 



In Strain III there are no posterior-nucleated forms. This is not to be 

 wondered at, as there are almost no short and stumpy forms, and it is only, or 

 almost only, among them that posterior-nucleated trypanosomes are found. 



Comparison of the Three Naturally Infected Dog Strains with One 



Another. 



Table XIV. — Measurements of the Length of the Trypanosome of the 

 Naturally Infected Dog, Strains I, II, and III. 



Date. 



Expt. 



No. 



Strain. 



Animal. 



Number of 

 trypanosomes 

 measured. 



Average 

 length. 



In microns. 



Maximum 

 length. 



Minimum 

 length. 



1912 





I 



Eat 



660 



23 -7 



36 -0 



15 '0 



1912 



911 



II 





500 



23 -9 



36 -0 



15 -0 



19] 3 



2037 



III 





500 



28 -4 



37 -0 



20 -0 



Table XV. — Percentages of Short and Stumpy, Intermediate, and Long and 

 Slender Forms in the Three Strains of the Naturally Infected Dog. 



Date. 



Expt. 

 No. 



Strain. 



Animal. 



Number of 

 trypanosomes 

 measured. 



Short and 

 stumpy, 

 15-21. 



Inter- 

 mediate. 

 22-24. 



Long and 

 Slender, 

 25-37. 













per cent. 



per cent. 



per cent. 



1912 





I 



Eat 



660 



47 -1 



10 -2 



42-7 



1912 



911 



II 





500 



38 -2 



9-2 



52 -6 



1913 



2037 



III 





500 



0-6 



4-8 



94 -6 



Strains I and II are similar, but Strain III differs so much from them 

 that it would be useless to combine the three into one curve ; the result 

 would be misleading. In Strain III, as will be seen from Table XV, almost 

 all are long forms. 



Table XVI. — Measurements of the Breadth of the Trypanosome of the 

 Naturally Infected Dog, Strains I, II, and III. 



Date. 



Expt. 

 No. 



Strain. 



Animal. 



Number of 

 trypanosomes 

 measured. 



Average 

 breadth. 



In microns. 



Maximum 

 breadth. 



Minimum 

 breadth. 



1912 



1218 



A 



Eat 



500 



2 -90 



5-00 



1 -25 



1912 



911 







500 



2-79 



4-75 



1-25 



1913 



2037 



ill 





500 



2 61 



4-00 



1 -50 



