347 
(30 ' passages ’), but occur also in Macacus rhesus (observed by Dr. 
Yorke), rabbits, and guinea-pigs infected with this strain. We have 
been unable to detect these forms in the case of sleeping sickness 
itself, for the number of trypanosomes present in the blood was 
always extremely scanty, and in infected rats showing an equally 
small number of trypanosomes we have also never been able to 
find them. 
A subsidiary but perhaps not unimportant point in the 
Rhodesian strain is that many of the ordinary long forms have an 
elongated posterior end, and may be termed ‘ snout ’ forms (figs. 
13-17). The ‘snout’ forms occur more especially during the first 
half or two-thirds of the period of infection in rats. 1 hese elongate 
forms, while not absent in the old laboratory strain of T. gambiense , 
yet are certainly more numerous in the Rhodesian strain, and even 
by means of this feature we are able to distinguish the strains. 
‘Snout’ forms were frequently seen in the blood of W.A. (figs. H> 
16), and in guinea-pigs. Bruce and Nabarro* have already noted 
these forms with elongate posterior ends. 
Again, although forms with the blepharoplast terminal (figs. 
18, 19) are found in the Rhodesian strain, they are less numerous 
than similar trypanosomes with terminal blepharoplast in the old 
laboratory strain. 
We may also note in passing that pear-shaped (fig. 1 0 01 
rounded forms with little or no free flagellum are not uncommon 
in the Rhodesian strain. 
SUMMARY AND CONCLUSIONS 
1. We attach some importance to the fact that the patient (now 
dead) from whom this strain was derived was never, as far as 
careful enquiries could elicit, in a Glossina palpalis area, but had 
been in many Glossina morsitans areas, and very probably in a 
small Glossina fusca area. 
2. These posterior nuclear forms (figs. 2-10) have not, as far 
as we are aware, been described either in the blood of sleeping 
sickness patients or in the blood of animals infected with 
^■ gambiense. Seeing how many competent observers have worked 
* Roy. Soc.: Reports of the Sleeping Sickness Commission, No. I, Pi- 2. Hg- 4 - 
W 
