being performed subcutaneously with a fine glass pipette on the inner side of
my left calf. Ten days following the inoculation nothing was to be seen, but
on January 9th a distinct nodule was felt, and on puncturing it, parasites were
readily found.

      Since returning to Madras, I have fed a large number of bugs on myself,
with the object of definitely finding out whether the parasite, after flagellating
in the adult bug, is able to live for long periods and to complete its cycle of
development; about 500 adult bugs were used in this experiment. The follow-
ing facts were definitely ascertained and which conclusively prove that the
parasite, when ingested by the adult bug and also by the nymph, never flagel-
lates at a temperature above 25°C. If hugs kept at this temperature contain
parasites the latter only degenerate. Adult bugs kept at a suitable temperature
(22° to 25°C.) and which had ingested parasites, always showed flagellates, but
they were never seen beyond the tenth day, clearly indicating that, in the adult
bug, the parasite does not complete its developmental cycle. It was also found
that the parasites never multiplied to any great extent, and no multiple
segmentation resulting in rosettes was seen. There is one point, however,
which requires further study, I have found that by keeping bugs at a tempe-
rature of from 18° to 20°C. the blood in their stomachs remains almost un-
changed up to 48 hours after it has been ingested, this being even more marked
in the nymphal stages. This suggests that the digestive process in the nymph
is not nearly as active as in the adult, and it could be readily understood that
in an adult bug kept at a high temperature, the parasite, on being freed from a
leucocyte, would find itself in a medium unsuitable for the profound changes
which take place between the pre-flagellate and the flagellate stages. It is
interesting to note that Oriental Sore in India only occurs in those parts where
there is a decided cold weather, for instance Karachi, Quetta, Jacobabad, Dera
Ismail Khan, Delhi, Lahore and Cambay. As far as I am aware it does not
occur anywhere south of Cambay or east of Delhi. While in Cambay I kept
accurate thermographic records and studied the temperature recorded at the
Hospital for the last 10 years. I found that during the cold weather, which
frequently begins in the middle of October and lasts till the end of February,
the temperature during the twenty-four hours keeps well below 25°C. I can-
not help thinking that there is a factor of fundamental importance underlying
the restricted geographical distribution of Oriental Sore in India, and I am
convinced that the explanation is to be found in the relation of the temperature
to the digestive processes in the bug.

      Having now narrowed down the investigation to the nymphal stages of the
bug, I decided to waste no more time in dissections, but to feed nymphs on

D 2