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No. V.
MAMMALIAN LEUCOCYTOZOA.
By the SUPERINTENDENT.
Within the last few years a number of parasites which have been classed with the
Hœmogregarinidœ have been discovered in the white blood cells of various mammals. Their
affinity to the well-known endoglobular parasites of cold blooded animals is chiefly based on
the appearance of the parasites
in the peripheral
blood. Although the Hœmogregarinidœ are by far the commonest endoglobular parasites they are ve
ry imperfectly known ; a reference to Dr. Sambons 1 recent list some 80 species, reveals the fact that except in the case of twelve their
Schizogony and Sporogony is unknown. At the present time there is no certain information
regarding the extracorporeal life histories of the cold blooded forms. Hintze's observations on
the Sporogony of H. minima is now universally believed to be incorrect and probably represents
part of the cycle of a species of Coccidium parasitic in the intestinal tract of Rana esculenta.
Siegel's account of the sporogenetic cycle of H. stepanovi in Placobdella catinigera has not been
confirmed ; Brumpt 2 has recently pointed. out that the thread-like sporozoits described by
Siegel are true leech spirochœtes and have no connection with H. stepanovi. I have fully
confirmed this observation of Brumpt as I have found. these Spirochœtes in the two leeches
4 common on frogs in Madras. In last year's report (Appendix XI) Captain Christophers,
I.M.S., gave a short account of the sexual cycle of Leucocytozoon Canis in the dog tick Rhipi-
cephalus sanginens ; since then a memoir describing the process in detail has been published.
It is not yet certain whether the method of reproduction of the Hœmogregarinidœ in their
vertibrate hosts is an asexual or sexual process. Labbe's observations on the hœmogregarines
of frogs suggest it is a specialised form of Schizogony and Lutz's work on the hœmogregarines
of snakes supports this view. It therefore seems somewhat premature to attempt to classify
these parasites as Dr. Sambon has done on the doubtful assumption that they produce "
sporozoits in secondary cysts or spore bags."
The Schizogonic cycles of these parasites require to be worked out in greater detail and at
the same time the exact nature of the various forms seen in the peripheral blood need to be
'ascertained ; such information will not only materially help in classifying the
Hœmogregarinidœ but will also throw some light on their extra-corporeal cycles.
I have had the opportunity of studying three of the peculiar mammalian forms, two of
which, Leucocytozoon fells domesticœ and Leucocytozoon leporis, are found in Madras and the
third Leucocytozoon funambuli in Kathiawar.
Leucocytozoon funarnbuli.— I have described this parasite fully in an earlier paper ; recently
through the kindness of Captain Coppinger, I.M..S., who sent me a large number of squirrels
Funambulus pennantii from Ra jkote, I have been able to study it further. It will be re-
. membered that after an exhaustive search in the liver, spleen and bone marrow I railed to
find its method of reproduction in the squirrel, I had however omitted to examine the lungs
where the Schizogony alone takes place. A short description of this cycle is as follows:—
The parasite on leaving the large mononuclear leucocyte enters an alveolar epithelial cell
and soon loses its vermicular shape. The epithelial cell becomes hypertrophied and stains a
deep pink with Giemsa's stain. The parasite on becoming round displaces the nucleus of the
cell to one side ; at the same time a cyst wall forms not only round the parasite, but also round
the whole cell. Important changes now begin to take place in the nucleus of the parasite, it
divides up into a number of chromatic filaments which are often seen bent in the shape of the
letter U ; this appearance suggests that the nucleus divides mitotically. On the formation of
the two nuclei they separate and soon begin to divide ; this process continues until the cyst
becomes studded with nuclei; its protoplasm is full of granules of various sorts. When fully
mature it occupies the whole of the cell, the nucleus of which being compressed atrophies ; it
now contains as many as 200 oval bodies which can be readily distinguished from the mature
parasite I have already described. In an heavily infected animal the capillaries of the lung are
found to be full of these young forms. There is no sexual dimorphism. The schizogony of
:Leucocytozoon Canis as described by Christophers is in many ways similar to the schizogony of
Leucocytozoon funambuli ; it however takes place only in the bone marrow of the dog and the
number of merozoits are much smaller.
This method of reproduction is quite distinct from that of Hœmogregarines which occur in
red blood cells, as the Hœmogregarines of frogs and snakes. This fact together with the
highly specialised nature of the parasite fully justifies its being placed in a distinct genus. It is un-
fortunate that the name Leucocytozoon has been used by Lühe to designate the parasites said to
occur in the white corpuscles of the owl (Athene noctua). It is doubtful whether these para-
sites of birds attack white blood corpuscles or immature red cells. We prefer to adopt
1 Manson—Tropical Diseases-1907, Appendix by Dr. Sambon.
2 Brumpt—Comptes Remdus Soc. Biologie, T. LXIII, 20th July 1907.
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