W. L. Yakimoff and others 
73 
Table 12. 
Solution 
l: 150 
l: 200 \ 
1:300 
1:400 
1:500 l 
1:600 
l: 700 
l: 800 ; 
Results 
Succumbed 
Survived 
Thus, for atoxyl the following results were obtained: 
dosis laetalis: solution— 1 : 150. 
dosis tolerata: solution—1 : 200. 
The results of the treatment of mice infected with trypanosomes are given 
in Table 13. 
Table 13. 
Days 
Solution 
1 
2 
3 
4 
5 
-Aw 
6 7 
8 
9 
10 
u 
N 
12 
l: 200 
+ V.f.© 
0 
0 
0 
0 
0 0 
0 
0 
0 
0 
rec urrence 
1 : 250 
+ v.f.© 
+f. 
0 
0 
0 
0 0 
0 
recurrence 
l: 300 
+ f.© 
+ 
0 
0 
0 
0 0 
recurrence 
l: 400 
+ © 
+ + 
+ + 
+ + + 
+ + + 
death 
l: 500 
+ f.@ 
+ 
+ + 
+ + + 
+ + + + 
99 
l: 600 
+ V.f.© 
+f. 
+ 
+ + 
+ + 
99 
l: 900 
+ f.© 
+ 
+ + 
+ + 
death 
l :1200 
+© 
+ + 
+ + + death 
+ v.f. denotes trypanosomes very few. 
+ f. = trypanosomes few. 
© = injection of the drug. 
From this table it is seen that in doses approaching the toxic doses 
(1 : 200, 1 : 250, 1: 300) atoxyl drives the trypanosomes out of the blood. 
When the solution is administered in the proportion 1 : 200 the trypanosomes 
disappear in blood on the next day; when 1 : 250 or 1 : 300 they disappear on 
the 3rd day after injection. 
But this disappearance of the parasites from the blood is only temporary, 
as the parasites reappear after some time and the weaker the dose the quicker 
the reappearance, e.g. 1 : 200—after 11 days; 1 : 250—after 8, and 1 : 300 
after 7 days. 
As regards weaker doses, the trypanosomes are not driven out of the blood, 
but death is postponed for 2 or 3 days, and in still weaker doses the period is 
shortened. 
If the trypanosomes are very numerous, even a solution of 1 : 300 does 
not expel the trypanosomes from the blood (see Table 14). 
