186 E. A. MINCHIN. 
the digestive tract (stomach, intestine, and proctodeeum). Of 
the six flies infected by T. grayi that I studied, in one case 
(Nov. 2nd, p. 238) I did not make any notes, unfortunately, as to 
the exact provenance of the trypanosomes. With regard to 
the other five, one (Nov. 10th, Ist fly, p. 241) had the trypano- 
somes only in the proctodeum. A second fly (Nov. 10th, 2nd 
fly, p. 241) had evidently not fed recently, and contained only a 
small quantity of black blood in the intestine, and trypano- 
somes were found only in the black blood and the proctodzeum. 
The remaining three flies (Nov. 13th, p. 243, Nov. 14th, p. 244, 
and Oct. 10th, p. 232) showed trypanosomes swarming through 
the red blood (stomach), black blood (intestine), and procto- 
deum. In my preliminary account of the encystation 
(P. R. 8.,8 79, p. 35) I stated that it was rare to find them in 
the proctodeeum, but I now recognise that this was a mistaken 
impression on my part; indeed, my limited experience 
indicates rather that the trypanosomes of this species always 
occur in the proctodzeum, even when they are absent in other 
parts. But I have never found T. gambiense in the 
proctodeeum. 
While I was at Entebbe I had little time to draw and 
study accurately my preparations, but I made a few drawings 
of my slides from one fly (Oct. 10th), and some of them were 
published in the preliminary report by Gray, Tulloch, and 
myself (P. R.8., B78, Pl. XIII, figs. 23 and 28). I have since 
then examined my slides of this fly much more carefully, and 
found that in this case also the proctodzeum contained vast 
swarms of the trypanosome (p. 233), a fact which I had over- 
looked at the time of writing my report. 
Trypanosoma grayi occurs under such a bewildering 
variety of forms and sizes that itis a matter of great difficulty 
at first to see any order or regularity inthem. This difficulty 
is increased by the fact that in one fly the trypanosomes will 
be found reaching a much larger size, as a whole, than in 
another; thus, in the flies of Nov. 10th (2), Nov. 14th, and Oct. 
10th, some of the trypanosomes are of very large proportions, 
while in the fly of Nov. 13th they are much smaller and more 
