6 Col. Sir D. Bruce and others. Trypanosome [July 15, 
This division of Zrypanosoma brucer into long, intermediate, and short 
forms is, of course, quite artificial, as the one form passes into the other by 
insensible gradations. It may, however, prove of some use in the identifica- 
tion of this species. In the same way a series of measurements of the 
various parts of the trypanosome body may also prove useful. The following 
table gives the. distance between the posterior extremity and the micro- 
nucleus, the micronucleus and the nucleus, the size of the nucleus, the 
distance between the nucleus and the anterior extremity, and the length of 
the free flagellum. 
Breadth.—The long and slender forms average 1°5 micron; the short and 
stumpy 2°5 microns. 
Shape-—As already mentioned, this is a markedly dimorphic species, 
composed of long, slender forms with free flagella, and short, stout forms 
without free flagella. It is curious that the long forms may preponderate in 
the blood one day and the short forms another. For example, as will be seen 
from Table I, the trypanosomes in the guinea-pig’s blood on October 11 were 
mostly short forms, giving an average of 20°7 microns, while a week later 
they were mostly long forms, giving an average of 27:1 microns. Note also 
Rat 16438, with an average of 19°6 microns, and Rat 1482, with an average of 
24-7 microns. 
This species may be compared with Dutton and Todd’s’ Trypanosoma 
dimorphon, and in truth the coloured drawings given by them in their original 
plate* (figs. WII, IX, and X) are very similar, if not identical, in shape 
and size with Zrypanosoma brucer. Fig. X, the long, slender form with free 
flagellum, is 30°5 microns in length. Fig. VII, the short, stumpy form without 
free flagellum, is 16 microns in length. As to fig. VI, on the same. plate, 
stated to represent the “ tadpole form,” one would suspect from its general 
shape and appearance that it had no connection with the others. But in 
regard to figs. VII and X, anyone comparing Dutton and Todd’s plate with 
the coloured plate accompanying this paper must be struck with the close 
resemblance between these two forms of TZrypanosoma dimorphon and 
Trypanosoma brucet. Is it possible that Dutton and Todd were dealing with 
Trypanosoma brucet when they described Trypanosoma dimorphon ? 
Contents of Cell—The protoplasm which is stained a pale blue is often 
dotted over with chromatin granules, especially. in the anterior half 
(Plate 2). In well-stained preparations the distribution and number of 
these granules is sufficient, according to McFadyean, to differentiate this 
species from TZrypanosoma evansi. This was also pointed out by Laveran 
* ‘First Report of the Trypanosomiasis Expedition to Senegambia (1902), University 
Press of Liverpool, 1903. 
