114 
A Sftfdf/ of Triipanosome Strains 
Again we have the remarkable result that all the human strains are statis- 
tically divergent beyond any possible comparison, except those of Chipochola and 
Chibibi which show a high degree of correspondence. Now is this result the 
outcome of treatment ? We note the following diversity of hosts : 
Strain I. 
Strain II. 
Strain III. 
Strain IV. 
Strain V. 
Gross 
Percentage 
Gross 
Percentage 
Gross 
Percentage 
Gross 
Percentage 
Gross 
Percentage 
Men 
60 
4-9 
0-0 
0-0 
0-0 
0-0 
]\[onkey ... 
100 
8-2 
160 
10-7 
160 
10-7 
160 
16-0 
160 
16-0 
Goat 
20 
1-6 
60 
4-0 
80 
5-3 
80 
8-0 
80 
8-0 
Sheei) 
60 
4-9 
20 
1-3 
0-0 
0-0 
0-0 
Dog 
260 
21-3 
260 
17-3 
260 
17-3 
260 
26-0 
260 
26-0 
Guinea Pig 
120 
9-8 
0-0 
0-0 
0-0 
0-0 
Rat 
600 
49-2 
1000 
66-7 
1000 
66-7 
500 
50-0 
500 
50-0 
Totals ... 
1220 
1500 
1500 
1000 
1000 
Now it will be clear at once that the percentages of trypanosomes drawn from 
various types of host are identical only in the case of Strains IV and V, which we 
have found in close accordance. But there is not great divergence in source 
between Strains II and III although Strain I shows fairly wide differences. We 
find, however, that II and III are statistically very unlike, the next closest 
resemblances, although very slight, being between II and IV and V. It would 
not seem therefore that the degree of similarity is wJiolly determined by similarity 
of hosts. I have accordingly reinvestigated the five human strains by taking rats 
only. But, of course, even then it is of vital importance to be certain that the 
process of transfer from man to rat was the same in all five cases, and of this no 
evidence is provided. 
Human Strains. B : From Rat only*. 
Microns. 
15 
16 
17 
18 
19 
20 
21 
22 
23 
24 
25 
26 
27 
Strain I, Mkanyanga 
1 
1 
21 
40 
52 
49 
30 
31 
36 
33 
48 
52 
II, E, Rat 728 
2 
4 
15 
30 
57 
72 
85 
72 
59 
44 
26 
II, E, Rat 726 
2 
24 
30 
42 
60 
61 
87 
73 
55 
27 
20 
„ III, Chituluka, Rat 952 
1 
3 
21 
27 
23 
15 
10 
15 
19 
21 
34 
44 
36 
„ III, Chituluka, Rat 953 
1 
17 
26 
20 
19 
15 
14 
26 
18 
33 
40 
34 
„ IV, Chipochola, Rat 1337 
4 
6 
16 
29 
53 
61 
59 
69 
56 
51 
36 
„ V, Cliibibi, Rat 1660 ... 
4 
17 
29 
46 
63 
69 
73 
52 
40 
31 
Sum ... 
1 
5 
47 
112 
161 
216 
290 
316 
376 
362 
322 
294 
235 1 
* R. S. Proc. Vol. 86, B, pp. 288, 289, 292, 293, 295, and 298. For Strain I see R. S. Proc. 
Vol. 85, B, p. 423. 
