400 
immediately after the parasitic fall the large mononuclears were 
filled with vacuoles and a reddish debris (stained Giemsa). Many 
of these vacuolated mononuclear cells were of great size (301040 
microns in diameter). We are inclined to think that this vacuolation 
with reddish stained debris may be an indication of the ingestion 
of trypanosomes, although we have never observed any definite 
trypanosome structure within them. 
F. W. Andrewcs, in the Croonian Lectures,* points out that an 
intravenous injection of bacteria causes a temporary diminution in 
leucocytes, followed by a marked increase, this fall and rise being 
chiefly due to the so-called polymorphonuclears, the mononuclears 
taking little part in the phenomenon. In this disease, as in malaria, 
it would appear that there is a diminution followed by an incre^e, 
chiefly of the mononuclears. This tends to suggest that the 
polymorphonuclear leucocytes react chiefly to bacterial infections, 
while the mononuclears would seem to react chiefly to protozoal 
blood infections (D. T). 
It is interesting to note that on May 20 there was a very marked 
mononuclear increase, coincident with a fall of trypanosomes, and 
accompanied by a remarkable improvement in the clinical condition 
ol the patient; and again on June 24 the mononuclear excess 
changed into a very marked polymorph excess. This was coincident 
with the onset of pleurisy and pneumonia, from which the patient 
died. 
In connection with the leucocyte cycle, the highest numbers 
lccorded were 50,000 per cubic millimetre of blood, whereas the 
lowest was 2,800 per cubic millimetre of blood. In the latter part 
of the chart the leucocytic graph is altered by the injection of 
leucocytic extract, and by the development of an abscess and 
pneumonia. 
I he following quotation from the ‘ Sleeping Sickness Bulletin, 
1908, Xo. I, p. 5, i s 0 f interest: — ‘Dr. W. Thomas found that 
altci an injection of atoxyl a change in the parasites became 
• noticeable between the fourth and the fifth hour. They became 
sluggish and much altered in appearance, and at the same time 
there was a noticeable increase in the leucocytes. About the seventh 
h oui th ere was a great diminution in the number of trypanosomes. 
'• Lancet, July, 1910 
