lO 
REPORT OF THE MALARIA EXPEDITION. 
Dr. Berkeley, medical officer of the Lunatic Asylum at the eastern suburb of Kissy, 
informed us that there had been a small outbreak of fever among the permanent inmates of that 
institution. Three persons had been attacked ; one had died, one had recovered, and one was 
convalescent. He was also good enough to bring us a number of gnats which he had caught 
within the institution. They proved to belong, almost all of them, to Anopheles ; and were of two 
species, one a small species which we have named J. funestus, and the other a larger species called 
A. costalis, Loew. The former were by far the more numerous. \_Addendum /., Plate FJ\ 
The insects brought by Dr. Berkeley were dissected and examined. In one a single 
characteristic zygote containing the melanin of H. vivax was found ; and since the melanin of 
this species is typical of it, it was scarcely open to doubt that the zygote had been derived from 
that human parasite. 
No further positive results, however, were obtained from this locality. No fresh cases of 
fever occurred, while we failed to find parasites in a large number of the Anopheles subsequently 
brought from the asylum. It was, however, interesting to observe these insects in the building. 
Large numbers of the small species were found gorged with blood and seated asleep in their 
characteristic attitude on the walls. They were most numerous on the ground floor and in the 
sleeping chamber of the inmates — who were not provided with mosquito nets. Few other gnats 
were present. 
In the meantime our attention had been called to the fever so prevalent among the troops 
at Wilberforce. On searching the barracks and hospital we found a considerable number of the 
large variety of Anopheles^ namely, A. costalis, already observed in small numbers at Kissy. As at 
the asylum, they were seen gorged and asleep in their characteristic attitude on the walls of the 
buildings, especially in dark corners, and were easily captured in test-tubes. Some were so 
excessively gorged that they had been evidently willing to fly only to the nearest part of the walls, 
just over the bed-heads of the soldiers on whom they had been feeding ; and those which were 
at once examined were found to contain human blood — or at least blood microscopically indis- 
tinguishable from human blood. 
The men — of whom about twenty slept without nets in each barrack — complained of being 
bitten by these insects at night, but added that they were occasionally annoyed also during the day, 
especially toward evening. It should be added that no other species of gnat were present within 
the barracks. During our stay in Freetown we must have caught or obtained at least two hundred 
gnats from these buildings, but only in a single case — a Culex — did the captures prove to be other 
than A. cosudis. We noted also that there were absolutely no vertebrates other than human beings 
within or in proximity to the barracks. Cattle, dogs, cats, bats, monkeys were absent, while, 
owing to the buildings having been newly erected, there were not even sparrows, lizards, etc. 
The Anopheles caught by us in test-tubes — almost all of them females which had evidently 
gorged themselves on the men during the preceding night — were reserved for microscopical 
examination. They were kept alive for 48 hours or more, until their meal of blood had been so 
far digested or voided as to permit an easy examination of the tissues of the stomach ; and were 
then killed and dissected — the stomach, the thorax, and the salivary glands being especially 
