A malaria problem.

Date:
1897
Catalogue details

Licence: Public Domain Mark

Credit: A malaria problem. Source: Wellcome Collection.

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    brown species, of which I have as yet obtained very few indi¬ viduals, I succeeded in finding in two of them certain remark¬ able and suspicious cells containing pigment identical in ap¬ pearance to that of the parasite of malaria. As these cells appear to me to be very worthy of attention, while the peculiar species of mosquito seems most unfortunately to be so rare in this place that it may be a long time before I can procure any more for further study, I think it would be advisable to place on record a brief description both of the cells and of the mosquitos. The latter are a large brown species, biting well in the day¬ time, and incidentally found to be capable of harbouring the filaria sanguinis hominis. The back of the thorax and abdo¬ men is a light fawn colour; the lower surface of the same, and the terminal segment of the body a dark chocolate brown. The wings are light brown to white, and have four dark spots on the anterior nervure. The haustellum and tarsi are brindled dark and light brown. The eggs—at least, when not fully developed—are shaped curiously like ancient boats with raised stern and prow, and have lines radiating from the concave border like banks of oars—so far as 1 have seen, a unique shape for mosquito’s eggs. The species appears to belong to a family distinct from the ordinary brindled and grey insects ; but there is an allied species here, only more slender, whiter, and much less voracious. My observations on the characteristics of these mosquitos were not very careful, as when I first obtained them I did not anticipate any difficulty in procuring more. On August 16th eight of them were fed on a patient whose blood contained fair to few crescents (and also filarise). Un¬ fortunately four were killed at once for the study of flagel¬ late bodies (flagellulaa cysts). Of the remainder two were examined on the 18th and 20th respectively, without any¬ thing being noted. The seventh insect was also killed on the 20th, four days after having been fed. On turning to the stomach with an oil-immersion lens I was struck at once by the appearance of some cells which seemed to be slightly more substantial than the cells of the mosquito’s stomach usually are. There were a dozen of them lying among (or within ?) the cells of the upper half of the organ, and, though somewhat more solid than these, still very delicate and colourless. They were round or oval, 12 n to 16 /n in dia¬ meter when not compressed (that is, considerably larger than the largest haemamceba in man) ; the outline sharp but very fine; the contents full of stationary vacuoles ; and no sign of apparent nucleus, contractile vesicle or amoeboid or intracellular movement. So far it would have been im¬ possible for any but a person very familiar with the insect’s anatomy to have distinguished them from the neighbouring cells ; but what now arrested attention was the fact that each of these bodies contained a few granules of black pig¬ ment absolutely identical in appearance with the well- known and characteristic pigment of the parasite of malaria (large quartans and crescent-derived spheres). The granules were more scanty in comparison to the size of the cell than in the hsemamceba, and numbered from 10 to 20 in each. They were not dispersed throughout the cells, but were collected in groups, or arranged in lines transversely or peripherally, or in a small circle round the centre (just as in some forms of the hsemamoeba). They were black or dark