152 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY
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Wenyon [1926], Reichenow [1929], and other authorities on the subject. Du Toit
classified the Piroplasmidea into two families, Babesidae and Theileridae, each
containing a number of genera. Wenyon considers the division into two families
as justified, but regards each family as containing a single genus, viz. Babesia and
Theileria. The characters of the families may be summed up as follows:
Family BABESIDAE Poche, 1913. Non-pigmented parasites of the red
blood-corpuscles of mammals which multiply in the corpuscle by division into two
or four. They are of varying size and shape, but usually arrange themselves in pairs
of pear-shaped individuals. The forms in the corpuscles are asexually reproducing
individuals, and possibly some are gametocytes. Genus Babesia Starcovici (1893).
Family THEILERIDAE du Toit, 1918. Non-pigmented parasites of the red-
blood corpuscles of mammals. Schizogony takes place in the endothelial cells of
the capillaries of the internal organs and the schizonts (" Koch's blue bodies ")
produce a number of merozoites. The parasites finally invade the red corpuscles,
within which they occur as round, ovoid, rod-like or irregular forms. They show
no tendency towards a paired arrangement. The forms in the red corpuscles do
not reproduce, and are possibly gametocytes. Genus Theileria Bettencourt,
Franca, and Borges [1907].
It is by no means easy to decide whether a particular form met with in the
peripheral blood is a Babesia or a Theileria. In the former, the organisms are
pear-shaped, and reproduce in the blood-corpuscles into two or four daughter
individuals which consequently show a tendency to pair. Sometimes, however,
as many as a dozen or more parasites can occur together in a single corpuscle.
This increase in numbers is due to budding or to multiple infection, and is not
comparable to the multiple fission as it takes place in Plasmodium. The parasites
produce no pigment, but destroy the corpuscles in which they are contained, and
set free the haemoglobin which is excreted by the kidneys of the host, producing
haemoglobinuria. In Theileria, on the other hand, schizogony takes place in the
endothelial cells of the capillaries of the internal organs and forms produced there
enter the red corpuscles and are seen in the peripheral blood. Unlike Babesia,
they do not multiply in the red corpuscles. The blood is consequently not infec-
tive when inoculated to healthy animals unless endothelial cells containing schi-
zonts happen to be present. Yakimov [1931] has given a useful and practical
scheme of dividing the genus Piroplasma Patton into two sub-genera, Piroplasma
s. str. and Babesiella Mesnil, dividing the species belonging to the latter into two
groups again. This scheme should however be followed, if at all, if the species
under consideration is definitely ascertained to belong to Babesia (Piroplasma)
and not to Theileria.
SPECIFIC IDENTITY OF THE FORM
Now we shall turn our attention to the particular species under reference.
According to the description of Piroplasma taylori as given by the author, the
parasites are mostly ovoid or round, pear-shaped forms being rare. When single