178 E. A. MINOHIN. 
forms are very rare. I have found them only in trypanosomes 
from the cerebro-spinal fluid, never in those from the blood, 
and in the former they are by no means universal. I con- 
sider the vacuolated condition as an abnormal one, due to the 
parasite being in unfavourable conditions, or tothe reaction upon 
it of a diseased enfeebled host. Bruce, Nabarro, and Greig (6, 
p. 20) express the view that trypanosomes do not find cerebro- 
spinal fluid so favourable for growth as blood, and are stunted ; 
they also note (loc. cit., p. 82) post-mortem forms, with large 
vacuoles, and deformed. Plimmer (85) regards the vacuolated 
form as “ probably due to some condition of environment.” 
Prowazek (86) has given three figures of T. gambiense_ 
(named by him T. castellanii), all of which differ a 
good deal from the appearances I am accustomed to see. 
His first figure (loc. cit., fig. 108) looks like a stumpy 
form with a vacuole, but it has a long free flagellum, and 
is perhaps an ordinary form deformed. His second figure 
(loc. cit., fig. 109) shows a long slender form, evidently 
in process of division, as » and WN are divided; that 
bemg so, one looks at once for the split flagellum which 
would naturally be found at this stage. The author has 
figured in the cytoplasm a slender filament which I identify, 
without hesitation, as the daughter flagellum not traced for 
its whole length. I think this figure throws some light on — 
the fibrils Prowazek introduces into so many of his figures of 
trypanosomes. ‘he author’s third figure shows a trypanosome 
“with long, narrow nucleus.” Never inall the many trypano- 
somes of this species that have come under my observation 
have I seen one with a nucleus such as Prowazek figures in 
this specimen; I am inclined to regard it as one in which the 
nucleus has become deformed in the process of smearing. 
In short, I can but state that Prowazek’s figures represent 
forms which, in my experience, are aberrant and abnormal ; 
whether this is to be explained by the influence of technique 
on the parasites, or of a European climate on their hosts, I 
leave an open question. I am convinced, however, that the 
appearance, and even the structure, of trypanosomes may be 
greatly affected by the condition of their hosts. 
