strain of T. gambiense (figs. 21-25), treated in the same way, 
i.e., dried films; 
2. Further, we have examined the trypanosomes under 
discussion, by intra vitam staining with methylene blue—by this 
method the posterior position of the nucleus can be seen; and finally, 
3. We have fixed wet films with sublimate-alcohol and with 
osmic vapour respectively, and subsequently stained them with 
haematoxylin, and found the same forms. 
Rats inoculated with the Rhodesian strain usually show a few 
long thin trypanosomes in the peripheral blood in about three days. 
The stumpy forms of trypanosomes with the nucleus posterior (figs. 
2-10) appear about the fifth or sixth day, and from this time 
onwards somewhat increase in number up to the seventh to eleventh 
day. They then form about six per cent, of the trypanosomes 
present, but may decrease again, varying from day to day.* 
These stumpy forms with posterior nucleus (as depicted in 
figs. 2-8) are ijn to 21 // long and 2/U to 3/i broad. The nucleus 
often shows a karyosome, and when at the level of the blepharoplast 
is often kidney-shaped (fig. 8). There is a well marked 
blepharoplast (kinetonucleus) and a definite undulating membrane 
with a flagellar border which terminates in a very short free 
flagellum. The cytoplasm of these forms is granular, especially at 
the anterior (flagellar) end, where coarse granules are seen in life, 
which granules are found to be chromatoid in nature on staining 
(figs. 2, 3, 5, and 8). These cytoplasmic characters are very like 
those seen in ordinary stumpy' forms of T. ganibiense (fig. 25). 
Sometimes a stained line is clearly seen in the stout forms, joining 
the blepharoplast to the nucleus (fig. 10). We have little evidence 
as to the relationship of these forms with posterior nucleus to the 
stumpy forms with the nucleus in the ordinary (central) position 
(fif>- 0» so content ourselves with pointing out that the existence 
of trypanosomes with posterior nuclei is quite characteristic of this 
Rhodesian strain, and is so marked a feature that we are always 
able in films to distinguish it from the old laboratory strain of 
T. ganibiense. 
These forms with the posterior nuclei are not confined to rats 
* The infected rats live about a fortnight. After the posterior nuclear trypanosomes are once 
seen they can be found on every subsequent day till the death of the infected'host. 
