26

Scientific Memoirs by

        In table I will be found the results of feeding 24 anopheles on malarial blood,
viz., 17 on blood containing summer-autumn parasites and crescents and 7 on
blood containing benign spring-tertian parasites. Of the former, 9 anopheles were
found to contain Ross' cysts in various stages of growth. The absence of cysts
in those mosquitoes fed on the blood of convict No. 9598 (crescentic bodies
absent) may have been due to the absence of crescents or to my having over-
looked them or damaged them during dissection. There were three failures in
those fed on the blood of convict No. 1718 which contained crescents. This
may have been brought about by three causes: either (I) the crescents were old,
(2) or immature, (3) or the large doses of quinine administered daily interfered
with the evolution. I attribute the failure to the last named cause, because many
crescents were "ripe." Excluding the three anopheles fed on convict No. 9598 for
the reason stated, we find 9 out of 13, or 70 per cent. approximately, infected.
This is not pleasant to think of but it is worse with those anopheles fed on spring-
tertian, because all became infected. Quinine was avoided when feeding the latter.

        My later experiments (not yet tabulated) give still better results with the
summer-autumn variety of hæmamœbæ.