236 
NOTE ON THE POLYMORPHISM OF 
TRYPANOSOMA GAMBIENSE. 
By E. A. MINCHIN, M.A. 
Plate XVII. 
In a memoir recently published, Salvin-Moore and Breinl 1 state 
that when Trypanosoma gambiense is examined in the blood “it does 
not seem possible to detect any true dimorphism or trimorphism.” 
“The three forms often described and alluded to as distinct, conse¬ 
quently appear to be arbitrarily chosen examples in a continuous series 
of dimensions.” It has always seemed to me very remarkable that the 
great differences in form and structure, no less than in size, between 
the slender, ordinary, and stumpy forms of T. gambiense, differences 
noted by all competent observers, should have been denied by two 
authors who claim for their methods of technique a superiority over 
those employed by all other investigators. 
In a preparation of T. gambiense from the blood of a rat, which was 
made by my friend and assistant Dr J. D. Thomson for the cabinet of 
the Protozoological Laboratory of the Lister Institute, the three typical 
forms of the trypanosome were found to be very distinctly differentiated. 
Dr Thomson found and marked two fields in which the three forms 
occurred in close proximity, so that it was possible to photograph them. 
The blood-smear was fixed wet with osmic vapour, stained with 
Giemsa’s stain, and mounted in Canada balsam. The two photographs 
which are reproduced here were taken at a magnification of 1000 
diameters by my friend Dr D. J. Reid. 
It can be seen clearly from the photographs that the difference 
between the three forms of T. gambiense is by no means one merely of 
size. The slender form is of great length and has a very long free 
flagellum. On the other hand the stumpy form is short and its 
1 Annals of Tropical Medicine and Parasitology , i. (1907), pp. 450, 451; compare also 
ii. (1908), p. 212. 
