TRYPANOSOMIASIS EXPEDITION TO SENEGAMBIA 
5i 
and is arranged in bands in the long axis of the body. These bands commence at 
the blunted end of the organism as fine streaks which gradually increase in thickness 
towards their centre and then tade away into the undulating membrane. In the 
simplest form of this parasite there are one or two such bands. The posterior end 
(the end remote from the flagellum) is round and blunted, and is occupied usually 
by a comparatively large unstained area- The undulating membrane is broad ; it 
commences 8 fx from the posterior end and extends along the base of the cone-shaped 
body, gradually decreasing in width. There is a general bluish mottling at the base 
of the undulating membrane. The flagellum runs along the undulating membrane, 
its free part extending for about 8 /u to 10 fx from the anterior extremity of the body. 
It is an extremely fine filament and does not stain well by Romanowsky's method. 
The micronucleus is seen as a crimson dot from which the flagellum arises ; it is 
situated near the centre of the body and is often difficult to make out. By careful 
focussing with a i" oil immersion a small, red-stained, rounded area can be made out 
either beneath or above the macronucleus, as the case may be. It is often obscured 
by the dark stained bands of the protoplasm above described. 
Besides this simple form of the parasite there are other larger forms which 
differ from it in the following manner :— 
(a) The posterior end of the organism is toothed. Three such ridges have 
been generally encountered in these forms. 
(/;) Instead of one or two there are generally three to four longitudinal 
bands of deeply staining protoplasm, which commence in these ridges and proceed, 
often in a spiral manner, towards the undulating membrane. Before their termination 
they generally present an unstained area. It would appear that these bands are 
slightly raised from the surface of the parasite. This may account for the striated 
appearance seen in the fresh state. In these larger forms the micronucleus and macro- 
nucleus are generally obscured by the darkly-stained bands. 
In stained preparations the average length of the parasite, excluding the 
flagellum, is 27 its width opposite the micronucleus is 3*2 and the width of the 
undulating membrane at this point in specimens of the type shown in Fig. 3 is 
4 - 5 //. Lavi'.ran and Mesnil* have already described this trypanosome as they 
observed it in stained specimens of blood taken from European green frogs. 
Trypanosoma mega. — New species (Provisional), Plate II, fig. 4. 
Many large trypanosomes, three to six in a coverslip preparation, were seen 
in the blood of a small frog, caught in a marsh at McCarthy Island, in January. 
Progressive movement was rather sluggish in these organisms, and was evidently 
brought about by contraction of the body protoplasm, as well as of the undulating 
membrane. Both ends of the organism tapered for some distance into a long fine 
* Laveran et Mesnil. Sur la structure du Trypanosome ties grenouilles et sur l'extension du genre Trypanosoma. 
, Gruby, Compt. Rend. Soc. Biol. Par. v. 53 (23), June 22, 1901. 
