!23 
When one of these parasites is obstructed by corpuscles or fibrin 
threads, the action again differs from that of other trypanosomes. 
Sometimes the ordinary lashings are produced, but more frequently 
the posterior end becoming a fixed point, the anterior circles round 
with regular sweeps, forcing the corpuscles away as the arc-like 
radiations pass from a burning catherine-wheel. The trypanosomes 
measure from 20 to 26/x in length, and up to 3'4/i at the widest part, 
posterior to the nucleus. The body tapers anteriorly from this in a 
rather regular fashion, while the posterior end is distinctly rounded. 
The blepharoplast is large, round or oval, measuring up to !> in 
diameter, and is usually terminal. The nucleus is commonly an 
elongate oval, up to 375/U in length and 2'5/u in breadth (average 
3’4 by 2), and occupies nearly the whole transverse diameter at this 
level. The undulating membrane is very narrow, about ifi, the 
bordering rim arises from the neighbourhood of the blepharoplast and 
IS continued as the flagellum after running parallel to the body, so 
giving an aspect of stiffness to the whole structure. For the greater 
part of its length this ‘ free ’ flagellum is accompanied by a 
continuation of the periplast, which may or may not contain cytoplasm. 
The actual free extremity does not appear more than 3'5/i in length, 
commonly less ; whilst the total length of the tapering end anterior 
to the cessation of the membrane is upwards of 8'5/U. The length of 
this whip was somewhat greater in the later stages of the disease, thus 
our figures in the inoculated calf, case IX, on August 4th (twenty- 
fourth day after inoculation) give an average of 3-4/1; those on 
September Sth (fifty-eighth day) vary between 3-4 and 8-5, with an 
average of 5-9/1. 
The cytoplasm stains homogeneously; vacuoles are seldom seen 
and granules are not very common. Dividing forms are rare ; in the 
peripheral blood we have only seen those with a double blepharoplast. 
We have never noted the alveolar arrangement of the cytoplasm 
described and figured by Liihe.® This trypanosome has retained its 
quite characteristic movement in fresh preparations and the same 
appearance in stamed films, excepting only the slight differences in 
the length of the anterior extremity, in all animals which took the 
experimental infection. 
