30 Drs. Stephens and Fantham. Morphology of a [July 19, 
As will be seen from the accompanying figures (Plate 6, figs. 2 to 10), 
the position of this “posterior” nucleus varies. Starting from the stumpy 
forms in which the nucleus is in the middle (fig. 1),. we have all transitions 
(figs. 2 to 8) up to that in which the nucleus is actually terminal (fig. 9) and 
posterior to the blepharoplast (kinetonucleus). 
We may meet here any objections that may be raised that the trypano- 
somes with posterior nucleus are due to distortion, dried films being used, 
because— 
1. We have never found them, though persistently looked for, in films from 
the same animals infected with the old laboratory strain of 7. gambiense 
(figs. 21 to 25), treated in the same way, 2.c. dried films ; 
2. Further, we have examined the trypanosomes under discussion, by 
itra 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 hematoxylin, and found 
the same forms. | | 
tats 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 to 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 6 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 to 8) 
are 17 to 21 long and 2p to 3p broad. The nucleus often shows a 
karyosome, and when at the level of the blepharoplast is often kidney-shaped 
(tig. 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 lite, which 
oranules 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. gambiense (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 
(tig. 1), so content ourselves with pointing out that the existence of trypano- 
somes 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 7. gambiense. 
