® 
1910.] Trypanosome from a Case of Sleeping Sickness, etc. 31 
These forms with the posterior nuclei are not confined to rats (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 to 17). The “snout” forms occur 
more especially during the first half or two-thirds of the period of infection 
in rats. These elongate forms, while not absent in the old laboratory strain 
of 7. 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. 14, 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 trypano- 
somes with terminal blepharoplast in the old laboratory strain. 
We may also note in passing that pear-shaped (fig. 11) or 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, ina 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 to 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 7. gambiense. Seeing how many competent 
observers have.worked with 7. gamliense, this is a striking point and can 
hardly be an oversight. 
3. We ourselves have been unable to find posterior nuclear forms, though 
constantly searched for, in the blood of rats infected with the old laboratory 
strain of 7. gambiense. 
4, Posterior nuclear forms exist also, as is well known, in 7°. transvaalicnse, 
and by Liihe these are regarded as developmental stages of ZY. theileri. 
* Royal Society : Reports of the Sleeping Sickness Commission, No. I, Plate 2, fig. 4. 
* 
