192 Major R. Ross and Dr. D. Thomson. Sleeping [Oct. 15, 
have happened to give atoxyl at the time when the leucocytes were increasing 
and the parasites were diminishing, as we have shown to occur naturally. 
(6) The Hemoglobin and Red Cells. 
During the course of the disease from February till the patient’s death in 
June, the hemoglobin percentage fell more or less steadily from 85 to 
70 per cent. We could not detect any variation in the amount of hemoglobin 
corresponding to the parasitic cycle. } 
The number of red cells was deficient (3,800,000 in March; 2,800,000 in 
June). Their numbers were not estimated frequently. 
(7) The Effects of Treatment by Various Drugs. 
The crucial test of a curative treatment in this disease would naturally be 
the effect of the treatment on the numbers of parasites, especially in our 
case, where the numbers were estimated daily. 
In testing the value of various therapeutic agents, we have therefore 
taken the graph of the number of parasites as the indicator of the efficacy 
of that agent. We would like also to point out that in estimating the effect 
of treatment by this method, the blood must be examined every day, other- 
wise the effects recorded might be erroneous. If a drug be given at the 
height of a parasitic rise, and the blood examined next day or a few days 
later, the number of parasites would naturally be much less; to conclude 
from this that the drug has caused this diminution might be quite erroneous. 
It is obvious that no conclusion should be drawn until the numbers have 
been estimated daily for several weeks. 
We think it may be possible that a drug such as atoxyl may by chance 
have been given, sometimes, just as the parasites were naturally about to 
fall, and the rapid diminution attributed to the drug. 
It has been stated that atoxyl did not always cause a disappearance of 
the parasites, but that sometimes instead they even increased in numbers; 
and further, that it seemed to have a more marked trypanocidal action when 
the parasites were very numerous. 
These statements can be understood in the light of the natural cycle. 
Again, if the trypanosomes increase in number immediately after the 
administration of a drug, one cannot at once conclude that this drug is of 
no value as a trypanocide. | 
THE EFFECT OF ATOXYL. 
From February 16 till April 5 atoxyl was not given on account of its 
injurious effect on the patieat’s eyes. On April 5 we, however, injected a 
ee 
