Karl Pearson 
125 
died of sleeping sickness*. With the single exception of T. hrucei every one of 
these distributions broke up into two components, and into two components with 
strikingly close means. I propose to call these two components T. minus and 
T. majus. I do not assert that they are distinct species ; they may be dimorphic 
groups of one and the same trypanosome species. But the recognition of their 
existence seems to bring some order at least into the chaos we have already noted 
as existing in the trypanosome measurements. Two human strains or two wild- 
game strains differ from each other with such wide divergence in their frequencies 
because these two groups T. minus and T. majus are mixed in the individual 
in different proportions. 
Strain 
Means 
Standard 
Deviations 
Coefficients of 
Variation 
Size of 
Populations 
T. minus 
T. majus 
T. minus 
T. majus 
T. minus 
T. majus 
T. minus 
T. majus 
T. rhodesiense 
18-7418 
26-1122 
2-3184 
3-4397 
12-370 
13-173 
I 343 -95 
I 34-4% 
\ 65-6 7„ 
T. brucei ... 
1^19-8244 
26-1122 
2-6439 
3-4134 
13-337 
13-072 
( 410-83 
I 41 -08 % 
j 589-17 "] 
\ 58-92 7J 
T. gambiense 
19-8926 
26-2463 
2-0566 
2-6260 
10-339 
10-005 
( 650-5 
} 65-1 7„ 
( 349-5 
1 34-9 7 „ 
Mzimba Strain 
G. morsitans Strain 
Wild-Game Strain 
Human Strain 
19-8966 
19- 6475 
20- 4418 
20-3687 
24- 0508 
27-1966 
25- 8263 
26- 2930 
1 -3961 
■ 1-7503 
1 -6332 
1-9444 
3-1028 
2-7013 
2- 8799 
3- 4470 
7- 017 
8- 908 
7-990 
9- 536 
12- 901 
9-932 
11-151 
13- 110 
( 634-96 
\ 63-5 7„ 
(1490-7 
i 59-6 /„ 
(1487-7 
i 59-57; 
(2621-4 
I 42-157, 
( 365-04 
'/ 36-5 7, 
p009-3 
1 40-4 7„ 
(1012-3 
\ 40-5% 
(3598-0 
( 57-85 7, 
Chituluka 
19-8410 
28-7875 
1-9785 
2-8823 
9-972 
10-012 
( 438-53 
( 29-247^ 
(1061-47 
I 70-76 7„ 
Means 
19-8315 
25-9542 
1 -8498 
3-0328 
9-360 
11-712 
T. simiae ... 
T. caprae ... 
17-870 
25-508 
1 •6558 
2-1011 
9-270 
8-580 
( 500 
\ 100% 
) 500 
( 100% 
The table below gives the chief biometric characters of T. minus and T. majus 
as found from the seven resolutions. The mean values of the constants for 
T. minus and for T. majus are placed at the foot ; in calculating these mean values, 
Cbituluka's data have been excluded as already included in the human strain, and 
also those for T. brucei not directly resolved. 
At the foot of the table I have placed the constants for T. simiae and T. caprae, 
the nearest pure strains to T. minus and T. majus respectively. I do not in the 
* R. S. Proc. Vol. 8ti, B, p. '291. 
