Insects and Disease 
623 
source I found a number of newly hatched mosquitoes like those first observed 
by me in Sigur Ghat—namely, mosquitoes with spotted wings and boat-shaped 
eggs. Eight of these were fed on a patient whose blood contained crescentic 
gametocytes. Unfortunately I dissected six of them either prematurely or 
otherwise unsatisfactorily. The seventh was examined, on August 20, cell 
by cell; the tissues of the stomach (which was now empty owing to the meal 
of malarial blood taken by the insect four days previously being digested) 
were reserved to the last. On turning to this organ I was struck by observ¬ 
ing, scattered on its outer surface, certain oval or round cells of about two 
or three times the diameter of a red blood-corpuscle—cells which I had never 
before seen in any of the hundreds of mosquitoes examined by me. My 
surprise was complete when I next detected within each of these cells a jew 
granules oj the characteristic coal-black melanin 0} malarial jever —a substance 
quite unlike anything usually found in mosquitoes. Next day the last of the 
remaining spotted-winged mosquitoes was dissected. It contained precisely 
similar cells, each of which possessed the same melanin; only the cells in 
the second mosquito were somewhat larger than those in the first. 
“ These fortunate observations practically solve the malarial problem. 
As a matter of fact, the cells were the zygotes oj the parasite oj remittent jever 
growing in the tissues oj the gnat; and the gnat with spotted wings and boat¬ 
shaped eggs in which I had found them belonged (as I subsequently ascer¬ 
tained) to the genus Anopheles. Of course it was impossible absolutely 
to prove at the time, on the strength of these two observations alone, that the 
cells found by me in the gnats were indeed derived from Haemamoebidae 
sucked up by the insects in the blood of the patients on whom they had 
been fed—this proof was obtained by subsequent investigations of mine; 
but, guided by the presence of the typical and almost unique melanin in the 
cells, and by numerous other circumstances, I myself had no doubt of the 
fact. The clue was obtained; it was necessary only to follow it up—an 
easy matter. . . . 
“Early in 1898, mainly through the influence of Dr. Manson, Sir H. W. 
Bliss, and the United Planters’ Association of Southern India, I was placed by 
the Government of India on special duty in Calcutta to continue my inves¬ 
tigations. Unable to work with human malaria—chiefly on account of the 
plague-scare in Calcutta—I turned my attention to the Haemamoebidae of 
birds. Birds have at least two species of Haemamoebidae. I subjected a 
number of birds containing one or the other of these parasites to the bites 
of various species of mosquitoes. The result was a repetition of that pre¬ 
viously obtained with the human parasites. Pigmented cells prec sely simi¬ 
lar to those seen in the Anopheles were found to appear in gnats of the species 
called Culex jatigans Wiedemann, when these had been fed on sparrows and 
larks containing Hcemamoeba relicta. On the other hand, these cells were 
