162 
Kli^POK'r OF TRAVELLING PATHOLOGIST AND PKOTOZOOLOGIST 
The host-cell, 
a peculiar 
form of 
erythrocyte 
T'wo main 
types of 
])arasite 
Oametocytes. 
male and 
female 
extremity of the spindle-l)ody a Proteosoma is in the stage of schizogony, while at the other 
end is a parasite which lias not yet reached this stage. If the whole spindle-body were the 
parasite, one would have to conclude that here is an illustration of one lilood parasite 
parasitic on another, or, in other words, a Proteosoma- parasitic on a trypanosome. This view 
is quite inadmissible, as this is merely an infection of one cell by two ditterent parasites. 
4. In several instances forms were seen which did not have the regular spindle structure. 
These are simply large cells of oval outline having the parasite curled round the nucleus. 
Apart from the size and the fact that there is no pigment these forms could readily be 
mistaken for Halter id ium, hut the character of the parasite leaves no room for doubt; this is 
only a much enlarged cell infected with the Lcucocytnzoon which has not produced the 
characteristic change in shape of its host-cell. 
5. The peculiar spindle shape of the host-cell has caused some confusion, and various 
theories have been advanced to overcome this difficulty. Most observers describe the 
cell as a leucocyte of some form. Laveran first suggested it to be a much altered 
erythrocyte, while others assert that it is an erythroblast. Above, attention has been drawn to 
the peculiar movements of the parasite within the cell and the waves which pass along its 
body towards the spindle ends, thus possibly helping in the production of the drawn-out 
processes. The type of cell infected also aids in the production of this shape. In the blood 
of birds and reptiles there are many cells of oval outline, which vary in size, but on an average 
approach the dimensions of the red blood-corpuscles. These cells possess no haemoglobin, and 
their nuclei resemble in many ways the nuclei of the red blood-corpuscles. A peculiar feature 
of these cells — wdiich may be young or immature red cells — is the property they have of being 
drawn out at each end. Such cells have been figured in Plate XVI., figs. 1, 2, 4. A cell of 
this type from the blood of the vulture has been figured in Plate XVII., /, in the Second 
Eeport of the Wellcome Eesearch Laboratories. An examination of a large number of slides 
in which young forms of the Lemocytozoon were present shows clearly the relation existing 
between these peculiar cells and the spindle-bodies. The tendency of these cells to become 
spindle-shaped apart from infection explains to some extent the spindle shape of the infected 
cells. A comparison of the uninfected cells (Plate XVI., figs. 1, 2, 4) with the young forms 
on the same Plate (figs. 5, 6, 9) will show clearly the relationship between the two. The 
fact that it is a cell devoid of haemoglobin which is infected explains the absence of pigment in 
the Lcucocjitozoon. 
6. In the case of Ilcemocystidiuni najte, the pigmented parasite of the red cells of the 
African cobra, one occasionally sees the infected red cells drawn out into spindle-shaped 
structures resembling very much the spindle-bodies of the guinea fowl (Plate XIV., fig. 21). 
From a consideration of the above points it seems to me quite clear that no other hypo¬ 
thesis explains the case than that the Leucocytozoo^i infects a cell in the same manner as occurs 
wdth every other known intra-corpuscular parasite, and, as a matter of fact, no other hypothesis 
wmuld be required apart from the endeavour to draw a comparison between these sjDindle-bodies 
and trypanosomes. It is quite evident that Schaudinn was mistaken in the description of the 
LeJieocytozomi viith which he worked, and likewise Button, Todd and Tobey in their account of 
the similar parasite of the grey hawk from the Congo. 
As described by Neave two main types of parasites are encountered in the blood, corre¬ 
sponding to male and female gametocytes. The female forms (figs. 8, 10, 20) have a dense 
protoplasm which stains deeply with Giemsa or Leishman stain. The male gametocytes 
(figs. 7,8,1.5) have a protoplasm which stains less deeply. These two forms correspond closely with 
the male and female gametocytes of Ilaltcridium. The absence of pigment can be accounted 
for by the absence of hoemoglobin in the infected cells. There are also differences in the nuclei. 
The nucleus of the female gametocytes consists of a group of chromatin granules usually closely 
