E. Hindle 
427 
By this method it was thus possible to see that the extra-nuclear 
granules were first formed within the tropho-nucleus and subsequently 
extruded into the cytoplasm. 
(a) The trypanosomes before drug treatment. 
The study of the normal trypanosomes, both in dry films stained with 
Giemsa, and in wet films stained with iron haematoxylin, has revealed 
the presence of three distinct types, and thus we can confirm the observa¬ 
tions of most investigators regarding the trimorphism of this parasite. 
The details of the origin and multiplication of these forms are reserved 
for a future publication, and in the present paper we shall merely con¬ 
sider the structure of the most common type of trypanosome occurring 
in the blood, viz., the indifferent form. 
In this type the kineto-nucleus is a small oval body situated a short 
distance from the posterior extremity. The end-bead of the flagellum 
is in very close relation to the kineto-nucleus so that the two structures 
usually appear united. Typically the tropho-nucleus consists of a small 
intra-nuclear centrosome surrounded by a clear ovoid space containing 
nucleo-lymph, which is bounded on the outside by a delicate nuclear 
membrane. The chromatin is usually precipitated on the centrosome 
in the form of a dense karyosome, but trypanosomes may be found in 
which the chromatin is precipitated on the nuclear membrane. Most 
commonly the tropho-nucleus, in addition to the karyosome, contains 
one or more chromatic granules, which are very variable both in number 
and size, but are usually ari-anged in a longitudinal series. 
In many of the trypanosomes, immediately in front of the kineto- 
nucleus, is a small vacuole, for which we propose the name “ kineto- 
vacuole,” from the anterior corner of which an achromatic axial filament 
runs down the centre of the body to near the anterior extremity. In 
many cases the axial filament arises from a small and rather indistinct 
granule on the edge of the kineto-vacuole, and it usually ends in another 
slight dilatation at its anterior end. 
The axial filament was first noted in trypanosomes by M. Robertson 
(1906) in T. brucei, and has since been found in T. gambiense, and 
T. equinum, by Swellengrebel (1909). Whilst on the whole agreeing 
with the observations of these two authors, those recorded below seem 
to point to the fact that the axial filament may not pass through the 
tropho-nucleus, but to one side of it, and the appearance presented by 
some of the trypanosomes in Swellengreberg figures may be due to the 
Parasitology in 28 
