46 
Piroplasma canis etc. 
diagnostic importance. {Vide also Nuttall and Graham-Smith do).) 
From the second day onwards the parasites continue their progress and 
increase in size. Generally there are two types to be distinguished, the 
one, with dark blue coarsely granular protoplasm and a small nucleus, 
is generally of an oval or worm-like shape, the other has a somewhat 
smaller nucleus and lightly stained protoplasm. 
On the second and third days one sees forms which point to the 
conjugation of two parasites of the same kind. One finds large masses 
of these pairs of forms in which the nucleus is hidden in the darkly 
staining protoplasm. 
As a result of this conjugation new forms are built up which look 
like small worms. They are described by Koch and Christophers. In 
our own preparations we could observe the gradual changes. The worm¬ 
shaped forms are apparently ‘ookinites’ very lively, and are present 
in large quantities in the saliva of the ticks with which the eggs are 
wetted. Later on we find globular shaped forms of various sizes which 
are probably formed from the above mentioned worm-like bodies. In 
the large globular forms the chromatin has undergone division into 
small fragments. Besides these forms we succeeded in finding large 
numbers of granular globular bodies of various sizes. If these are various 
stages of development of Piroplasma as Koch takes it, or various cells 
of the tick it is at present difficult to decide. If, however, one may 
judge according to the analogy with other protozoa we may well accept 
the first suggestion.” 
In the egg these observers could find no parasites, though in the 
case of Piroj)lasma canis there is no doubt that forms occur embedded 
in the yolk. Koch also describes forms found in the egg. 
Marzinowski and Bielitzer also describe and figure the small forms 
in the salivary glands. They say in conclusion : 
“In this way we succeeded in observing the development of Piro- 
plasrna in the bodies of ticks and in the larva, our results coinciding 
completely with those of Koch and Christophers and being even partly 
supplemental to these.” 
However obscure the exact significance of the different stages may 
be, some idea of the general nature of the cycle of Piroplasma can be 
formed. 
There is no doubt that certain parasites taken into the gut of the 
tick, after an enlargement as described by Marzinowski and Bielitzer, 
become club-shaped bodies and leave the gut. The formation of these 
club-shaped bodies I have followed very clearly. Marzinowski and 
