15
It has been found that during .the colder months (December and January) this change
hardly ever takes place, while in a leech taken from a frog in September the parasites had not
only immediately left the red cells, but had also passed out of their capsules. These observa-
tions suggest that the further evolution of the parasites will best be studied during the hot
weather when it is hoped to make an exhaustive study of their life cycles not only in the leech
but also in the frog.
No.
BATRACHIAN TRYPANOSOMES.
By the SUPERINTENDENT.
We owe our exact knowledge of the morphology of the trypanosomes of frogs to the
researches of Laveran and Mesnil on the trypanosome of Rana escalenta which was the parasite
originally studied by Gluge, Mayer, and Gruby. Trypanosoma rotatorium vel sanguinis of Mayer
and Gruby undoubtedly exhibits marked pleomorphism in its vertebrate host and as Laveran
and Mesnil suggest many of the trypanosomes of frogs described by subsequent observers as
distinct species may quite well be special forms of this parasite. Trypanosoma
inopinatum described by the brothers Sergent has been accepted by most authorities as a new species ; this
also applies to trypanosoma nelspruittense of Laveran, Trypanosoma borelli of Marchoux
and Salimbeni, trypanosoma solomalense of Brumpt and trypanosoma belli Nabarro.
Franca and Athias have recently suggested that the species rotatorium of Mayer-Gruby
should be divided into two species; (1) T. loricatum or costatum (Mayer) in which the body of
the parasite is ovoid and the blepharoplast is situated near the nucleus ; (2) T. rotatorium
(Mayer) in which the body is more slender, the blepharoplast is situated at the posterior end
and the undulating membrane is well developed.
These observers have also described two new species T. undulans and T. elegans.
In Rana tigrina and Rana hexy dactyla I have found the typical Trypanosoma rotatorium vel
sanguinis of Mayer-Gruby as well as forms allied to Trypanosoma mega and Trypanosoma
karyozenkton of Dutton and Tood and the T. undulans of Franca and Athias. In addition to these
forms I have also seen a small trypanosome in the blood of Rana tigrina measuring from 27
ν to 28 ν including the free flagellum which is about 7 v to 8 v in length ; its posterior end is
markedly pointed and beak-like, its body is narrow and the undulating membrane is of medium
breadth. The blepharoplast is situated about 2.5 v from the posterior end ; the nucleus is
small and oval and lies about the centre of its body. The parasite stains pink throughout and
exhibits no striations or granules. It appears to differ from the two other small trypanosomes
of frogs Trypanosoma inopinatumm and Trypanosoma belliI therefore propose naming it
provisionally Trypanosoma hendersoni after Dr. Henderson through whose kindness in obtaining
the frogs I had the opportunity of studying this parasite. An interesting question arises as to
the possibility of these small trypanosomes having some connection with Trypanosoma rotatorium?
I have always found Trypanosoma hendersoni associated with rotatorium and never in large
'numbers. It is not possible to answer this question finally until the development of the two
parasites in leeches is thoroughly worked out, further a large number of feeding exerperiments
would also be necessary to see whether soon after infection it is possible to trace any connection
between the two forms. In the blood of Rana tigrina and Rana hexidactyla infected with
Trypanosoma rotatorium I have seen all the curious forms figured and described by Franca,
Athias, Dutton, Todd and Tobey ; it is not possible as yet to say what part of its life cycle they
represent.
In the leech (Clepsina), more particularly in the embryos, I have been able to study the
development of a flagellate, which appears to be a true parasite of the leech. Twenty-four hours
after feeding on an infected or uninfected frog round non-flagellated forms are seen lying free
in the crop diverticula; in many of these early forms I have seen yellow granules exactly similar
to the well known pigment granules of the Hœmocytozoa. I am not aware that this has been
described before. The parasites multiply by longitudinal division and later develop flagella
and all the stages from the small, round, non-flagellated forms up to parasites with long
flagella were readily seen. The flagellates now increase in length and lose their blue staining
character and instead stain pink throughout—in all these forms the blepharoplast was always
situated either anterior or close up to the nucleus Except for this fact they were not unlike
Trypanosoma hendersoni. Owing to the small size of the embryo leeches and their transparent
cuticles these flagellates can be readily studied in the fresh condition. They occur in all the
diverticula and are not localised to one particular part, One batch of embryo leeches fed on a
frog with exceedingly few T. rotatorium and T. hendersoni developed enormous numbers of these