Chapter XXIX 
THE TRYPANOSOMIDAE 
TEe c Irypanosomidae comprise two genera— 
(i) Trypanosoma , (2) Trypanoplasma. 
Trppanosoma .—TEe genus is cEaracterised by tEe 
possession of a longitudinal undulating membrane, 
the thickened border of which takes its origin 
posteriorly from a blepharoplast, and terminates 
anteriorly in a free flagellum. Division takes place 
longitudinally. 
Structure of Trypanosomes .—In the gut of the 
louse certain non-flagellate forms of T. lewisi are 
described, which have a single oval nucleus only. 
From this nucleus eventually arises by division the 
blepharoplast, or nucleus regulating motility. This 
shews that this structure is nuclear in origin and, more¬ 
over, as the flagellum now appears at the end of the 
young developing trypanosomes where the blepharo¬ 
plast is, this flagellum-bearing end is the anterior one ; 
and it is only later that it takes up its ordinary posterior 
position. Besides the blepharoplast, the undulating- 
membrane, and the flagellum, mynonemes are also 
described. These ectoplasmic fibres are not generally 
seen in the ordinary methods of staining. They are 
most readily demonstrated in large trypanosomes like 
T. rotatorium or T . theileri , especially if the trypano¬ 
somes have been eviscerated by the pressure of making 
a blood film or by the action of macerating fluids. 
Besides these details of minute structure, some 
authors consider that trypanosomes exhibit— 
Sexual Differences .—These differences are not 
