190 Major R. Ross and Dr. D. Thomson. Sleeping [Oct. 1b, 
The urine throughout remained clear, usually slightly acid and without 
deposits. The specific gravity ranged from 1010 to 1026. | 
On March 15 he had a diffuse ill-defined erythematous rash over his left 
leg, occurring just before the height of a trypanosome increase. 
(5) Correlation between the Trypanosome Cycle and the Behaviour of the 
Leucocytes. 
Previous to April 23 we made several leucocyte counts with the Thomas 
Zeiss apparatus, but were unable to find anything definite. It was only 
when we made counts daily at the same hour that we were able to find 
a definite leucocyte change corresponding to the parasitic cycle. 
We counted the leucocytes by means of the thick film as referred to in 
our paper on malaria, and were astonished at the remarkable variations. 
We found no such variations by our method in normal persons. Simultaneous 
examination of thin blood films also showed that a remarkable leucocytic 
variation did take place, corresponding to each rise of trypanosomes. 
Daily differential counts were also made in thin films stained with Giemsa, 
in which we distinguished only between mononuclears and the so-called 
polymorphonuclears. In these we never counted less than from 300 to 500 
leucocytes to ensure greater accuracy. We thus estimated daily the total 
leucocytes and the total numbers of polymorphs and mononuclears per 
cubic millimetre of blood, as shown in the chart and table at end of paper. 
From April 23 till May 20 it is clearly seen that coincident with each rise 
in the number of trypanosomes there is a marked increase in the total 
leucocytes, and this increase is due more to mononuclears than to polymorpho- 
nuclears. 
When the trypanosomes begin to increase in number the leucocytes 
increase also, more especially the mononuclears. When the trypanosomes 
have reached their height there may be a fall in the number of leucocytes, 
but this is followed by a still higher rise during the fall of the trypanosomes. 
The leucocytes would seem to reach their highest numbers on about the 
third day after the height of the parasitic cycle. They then decrease rapidly 
for about three days to normal or much lower. When this occurs the 
trypanosomes again commence to multiply, and the leucocytes again 
increase also, so that we have both a parasitic and a corresponding leucocytic 
cycle. 
We did not attempt to differentiate between large mononuclears and 
lymphocytes, but it seemed to us that both took part in the total mono- 
nuclear increase. We further observed that during and immediately after 
the parasitic fall the large mononuclears were filled with vacuoles and a 
