9

bodies are seen included in cells, but I have searched in vain for free bodies, and if
present at all they must be in very small number only.

     The blue staining substance in which some of the bodies are seen is of great
interest, and upon the interpretation of its nature the zoological position assigned
to the parasite depends. The appearance of this substance varies slightly in differ-
ent preparations. It stains faintly or more darkly blue and shows a hyaline, finely
granular or reticular structure. It may be, and often is, about the size of a red
cell but it may be very much smaller and it may be larger. If small, it usually con-
tains only a single body. When five or more bodies are present the size exceeds
that of a red cell. The outline is often very distinct, but it is sometimes blurred
or quite irregular. In some cases the resemblance to a red cell altered by the
simple tertian parasite is very marked. Distinct stippling is not, however, seen.
Bodies resembling these, but not containing parasites, are generally numerous in
preparations showing included forms. If blood containing the bodies is placed in
a hypotonic solution of ammonium oxalate and the centrifugalised sediment
examined, the blue staining material around the bodies becomes more clearly
defined and stains more darkly blue. At the same time the protoplasm of the
mononuclear leucocytes shews a marked tendency to budding and separation from
the cell and stains more clearly. But the red blood corpuscles are seen only as
ghosts.

     In one of the cases examined by us during life and post mortem, bodies resem-
bling altered blood cells contained undoubted malarial pigment. In the large
macrophages similar pigment was seen included in the same cell as the
parasites.

     I think there can be no doubt, therefore, that very many of the blue staining
bodies in which included parasites are seen, are pieces of detached cell protoplasm
derived from the large mononuclear cells and especially from the macrophages.
In many preparations the process of detachment may be observed, and buds of
protoplasm containing parasites are seen projecting from the cell mass. The
process appears to be assisted by the addition of hypotonic solutions and may
be largely due to the fluid always present in the syringe when used for spleen
puncture.

     Whether the blue substance is always of leucocytic nature, whether some of
the bodies seen are really red cells (Fig. 19), I hesitate to say; but however
striking the resemblance to the red cell may have been, we have always found the
protoplasm of the leucocytes to be similarly stained.

     Relation of the parasites to leucocytes.—A most striking feature in connection
with the bodies is their presence in great numbers in an unchanged state in the