788 E. A. MINCHIN. 
shorter body, plastic and (after death) inert, we can under- 
stand the body being thrown into curves by the elasticity of 
the flagellum, which, being longer, necessarily runs on the 
outside of the curves. Only in a single instance have I seen 
the marginal flagellum on the concave side of a curve in a 
preparation of T. lewisi (fig. 9), and in this case the 
flagellum showed a double bend with sharp angles at this 
point, suggesting a forcible pleating of the flagellum, owing 
to the fact that the body, wedged in between blood-corpuscles, 
was unable to take the curvature which the elasticity of the 
flagellum would naturally cause. 
I give in a table below a number of measurements of ten 
trypanosomes from standard preparations made in the follow- 
ing way. ‘The trypanosomes were first of all carefully drawn 
with the camera lucida, projected to a magnification of 3000 
linear, as determined by substituting for the trypanosomes a 
stage-micrometer, of which the divisions were drawn in the 
same manner and the resulting scale measured. The magni~ 
fication thus obtained depends, other things being constant, 
on the height of the camera lucida from the drawing board, 
that is to say, on the length of the tube of the microscope. 
By trial a length of tube was found, which, with the com- 
bination of lenses used, projected the divisions of the micro- 
meter-scale, each representing ‘01 mm., to a scale in which 
they were 30 mm. apart. Taking the magnification of 3000 
obtained in this way as accurate, the measurements shown in 
the table were obtained. 
The measurements were carried out by following the 
undulations of the trypanosomes in the figures with a piece 
of thread, the length of which was then measured in -milli- 
metres; the figure obtained was divided by three, and the 
resulting figure represents, therefore, the actual length in 
microns. The pre-nuclear region is measured from the 
karyosome, or when two nuclei are present (fig. 6) from the 
boundary between them, to the extreme anterior end of_the 
body ; the free flagellum from the latter point to the end. 
As it is often difficult to determine exactly the anterior 
