98 
A Study of Trypanosome Strains 
(e) It seemed well worth while to investigate how far the two Nyasaland 
strains of Human Trypanosomes given in the table on p. 95 agree or differ. The 
first (6) of these strains from a native woman of Nyasaland may be compared with 
(c) a compound strain from four natives and a European. We find 
= 172-36 
giving P< -000,000,1. 
In other words, the two Nyasaland strains from human beings are indefinitely 
diiferentiated. I now compare the Mzimba (Donkey) strain* (a) with human 
strains (6) and (c), we find : 
for (a) and {h) = 223-16 giving P certainly < -000,000,01 ; 
for (a) and (c) 348-55 „ „ < -000,000,01. 
Thus the trypanosome strain found in the donkey appears to be absolutely 
incomparable with that found in man in Nyasaland, just as the strain found 
in the donkey differed from that found in wild-game. 
(./') "^^y i^o^v t^^ii to a memoirf by Sir David Bruce and others com- 
paring the Mvera cattle strain, the wild-game strain, and the wild Glossina 
morsitans strain. They give on p. 13 of that paper the graphs for 500 specimens 
of T. pecorum, the wild-game strain, and of the wild Glossina morsitans strain taken 
from a variety of hosts. The following are the fx-equencies : 
Microns. 
Strain 
9 
10 
11 
12 
13 
U 
15 
IG 
17 
18 
19 
Totals 
Mvera Cattle Strain 
1 
1 
15 
64 
101 
136 
114 
59 
8 
1 
500 
Wild-Game Strain ... 
2 
34 
85 
172 
119 
63 
22 
3 
500 
Wild G. morsitans Strain ... 
1 
4 
16 
42 
129 
147 
103 
42 
15 
1 
500 
We compare first Mvera cattle strain with the wild-game strain and find for 
our 10 categories 
^2 = 34-554, P= -000,243. 
This is a relatively low degree of divergence considering that P has been running 
into 1 in 10,000,000 ! But it means that if these two strains were samples of one 
and the same population, we should only expect two such divergent samples to 
occur 1 in 4000 trials. 
* This Mzimba strain of trypanosome is discussed in a paper headed : ' Morphology of the various 
strains of Trypanosome causing Disease in Man in Nyasaland. — The Mzimba Strain ' [R. S. Proc. 
Vol. 87, B, p. 26) ; it is said to be of the Nagana type and is identified by Sir David Bruce and 
colleagues with T. hrucei vel rhodesiense, the source of the human trypanosome disease. 
t -R. S. Proc. Vol. 87, B, p. 4. 
