164 
KEPORT OF TRAVELLING PATHOLOGIST AND PROTOZOOLOGIST 
The true 
nature of 
the “ line" 
The nucleus 
of the host-cell 
favourable examples as a red line extending all round the parasite (fig. 12), In other cases 
the line does not extend all the way round the parasite, but only on that side opposite the 
host-cell nucleus (fig. G), and in those parasites where the nucleus lies against this side it might 
easily he supposed that there is some connection between this line and the chromatin of the 
nucleus. Figs. 24, 27, 32 of Dutton, Todd and Tohey show such a parasite in which the red 
line at the margin of the parasite has been interpreted as the “ line ” arising from the nucleus. 
If now attention is turned to parasites which are altered in shape or distorted, it will he 
noted that this line, which in reality lies round the margin of the parasite, takes up various 
positions in the cell, and may lie across the middle of the parasite. In such cases it would 
he easy, if material is limited, to miss the true nature of this line. Further, owing to a 
longitudinal creasing of the host-cell, which sometimes occurs in preparations, various red 
staining lines appear which extend across the parasite from the host-cell, and may even 
produce appearances of longitudinal division of the “ line.” 
After examination of a much greater amount of material than was possible for them, 
I am convinced that the description of the development of the “line” given by Dutton, 
Todd and Tohey is an erroneous combination of the appearances of several distinct objects 
produced by the distortion of the parasites in the blood films examined. It may be mentioned 
here that the red line which appears round the parasite as in figs. 6 and 12 is probably due to 
the fact that the spiiidle-body is flattened or leaf-like, and is not cylindrical. This flattening 
is not due to the spreading of the film, but is equally observed in the fresh blood. The red 
line appears at the edge of the parasite, which is really a flattened piece of protoplasm. 
The arrangement of the nucleus of the host-cell in reference to the parasite varies very 
much. In some cases it is much elongated (figs. 11, 15), in others it is little altered in 
shape, while in some it tends to surround the parasite (fig. 19). At fig. 3 is depicted a small 
parasite indenting the nucleus, and the same appearance at fig. 16. Generally speaking, the 
smallest parasites that could be detected were seen lying against the nucleus of the host-cell 
in the manner just described. The staining of the host-cell nuclei varies greatly. In the 
youngest forms observed (Plate XVI., figs. 5, 6) the staining is exactly like that of the nuclei 
of the uninfected cells (Plate XVI., figs. 1, 2). As the parasite grows the cell enlarges and 
the nucleus with it. At the same time the nucleus is altered and stains differently, so that 
care must he exercised in attempting to judge of the type of cell infected from this enlarged 
and altered cell. It resembles more a mononuclear leucocyte, and it is this fact that has 
probably led to the host-cell being described so often as a leucocyte. 
The movement of the gametocytes in the fresh blood has been described above. Fig. 18 
shows a female gametocyte which has escaped from the host-cell, and fig. 17 a male gametocyte. 
In no case, either in stained films or in fresh blood, has the formation of the microgametes been 
observed, but in one film several appearances like the one depicted in fig. 27 were encountered. 
In the same film Halteridium occurred together with the Leucocytozoon. The large body 
depicted is undoubtedly the macrogamete of the Leucocytozoon, and unless the microgametes 
are those of Halteridium this is the fertilization of the female gamete. It is improbable that 
the microgametes of Halteridium wovld cluster round the macrogamete of another parasite, and 
as this figure resembles that given by Schaudinn of fertilisation in the parasite of the owl this 
is probably the correct view. In Sehaudinn’s figure the microgametes are shown as small 
trypanosomes -with an undulating membrane. In this case the microgametes show nothing of 
the trypanosome structure after the most careful examination. They resemble the microgametes 
of the malarial parasites, and consist of a protoplasmic portion with chromatin arranged 
longitudinally. 
The appearances of this parasite have been dwelt upon at some length on account of its 
connection with the similar parasite of the little owl with which Schaudinn worked. Though 
