26 
Blood Parasites 
The Fusiform Trypanosomes. The body is long and is generally 
about five times as long as it is broad. The greatest width is about the 
middle third, and the body usually tapers to a fine point at each end. 
(Plate II, fig. 1.) 
The protoplasm stains a deep blue colour and in or under the 
periplast very distinct myonemes are seen. These run as longitudinal 
striations and ai'e stained bluish or purplish alternating with lighter 
streaks, and with critical illumination they can be resolved into a dotted 
appearance. They continue over the nucleus and for the most part run 
parallel on the two surfaces of the body, at other times they cross 
giving the appearance of lattice work. Chromatoid granules are 
generally absent. The posterior or aflagellar end is in typical examples 
drawn out to a fine point, but not infrequently it is rounded off and 
quite obtuse. The centrosome stains very deeply, it is usually round, 
sometimes rod-shaped, and lies about o'o p, from the posterior extremity, 
but as the latter is a very variable factor, it may be as far as 11 /i. 
Immediately anteriorly to the centrosome is almost invariabl}' an 
unstained area through which the attached part of the flagellum can be 
ti-aced to the kinetonucleus. 
The fiag-ellum arises from or near the centrosome and runs forward 
obliquely through the vacuole to the surface of the body, forming the 
margin of the undulating membrane, and finally leaves the anterior end 
of the body as the free flagellum. The undulating membrane is thrown 
into a number of curves, generally five or six, and is consequently longer 
than the length of the trypanosome measured from the centrosome to 
the extreme anterior end. 
The nucleus is situated in about the middle of the body. Usually 
it is in the form of a half circle with the convexity towards the 
concavity of the trypanosome. It is sometimes I’ound, and measures 
about 4 yii in diameter. 
With Giemsa’s or Leishman’s stain it appears as a somewhat dense 
collection of chromatin granules. When the stain has been more 
extracted the margins appear more deeply stained and consist of a 
number of granules with a central paler area. The free flagellum is 
about one eighth the length of the body of the parasite. 
The Piriform type of the Trypanosome. This has a shorter but 
much broader shape, the average length of the body, without the 
flagellum, being .about 20 y and the width 8’8 y. (Plate II, fig. 2.) 
The anterior and posterior extremities are usually pointed, hut in 
many the posterior end is rounded. 
