Report on the cultivation of proteosoma, Labbé, in grey mosquitos / by Ronald Ross.

  • Ronald Ross
Date:
1898
Catalogue details

Licence: Public Domain Mark

Credit: Report on the cultivation of proteosoma, Labbé, in grey mosquitos / by Ronald Ross. Source: Wellcome Collection.

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    mouthed glass vessels covered with muslin or stopped with a plug of cotton wool, and will soon hatch out into the perfect insect. The subject, whether a man or a bird in a cage, is put on a bed. The ordi¬ nary mosquito-netting (in good repair) used in tropical countries is suspended over the bed and is tucked under the mattress on which the subject has been placed. The jar of mosquitos is introduced under the netting and is opened, thus liberating as many of the insects as we wish. For birds a special netting may be devised. Mosquitos gorged with blood are easily recognised at sight. They are caught by an assistant entering the net and placing a test tube slowly over them as they sit on the gauze. A number of tubes containing a given stock of fed mosquitos is kept in the manner used in bacteriological laboratories for tube cultures; and the insects are killed by chloroform or tobacco-smoke. Tubes containing mosquitos should be lightly plugged with cotton-wool 5 should have a few drops of water at the bottom for the inmates to drink (sic), and lay their eggs in, and should be changed for fresh clean tubes every morning. The females are fecundated shortly after feeding. Grey mosquitos fed at night remain gorged and asleep for all the next day and night. Towards the end of the second day, however, the stomach begins to “ clear,” that is the meal has been partly digested and partly evacuated, leaving the organ empty. The eggs are usually laid on the third day (with grey mosquitos), after which the insect generally dies if it has not been fed again in the meantime. In order to keep them alive for long periods they must be fed again every two Jays. In this manner I have kept them for twelve days; and, even after that, saw by the state of their ovaries that they could have lived longer. As with other animals, feeding is necessary to their existence. In order to refeed a stock, the test-tubes are simply opened under a mosquito-net containing a crow or sparrows, and the insects are caught again next morning as usual. A mosquito is dissected for examination of the stomach in this manner. A needle, held in the left hand, is passed through the thorax, the legs and wings are pulled off, and, if necessary, the scales of the body brushed off with a camel- hair brush. The tail is then lowered into a drop of water, salt solution or weak formalin placed on a glass slide; and with another needle held in the right hand, the last two segments of the tail are partially separated and held down upon the slide. The left hand is then moved in such a manner as to draw away the insect. If done skilfully, the alimentary and generative apparatus will remain on the slide attached to the last two segments of the tail. If necessary, as when the stomach is full, the last two segments may be entirely separated and the alimentary apparatus drawn out by the oesophageal end, The alimentary canal consists of an oesophagus, a single sac, the stomach, and a short, straight (?) intestine leading to the anus and containing six heart- shaped glands near the rectum. Five long tubes, the malpighian tubes, open into the stomach at its junction with the intestine. The stomach is roughly about 2*5 mm. long and between *5 mm. or i*o mm. broad when uncompressed by the cover glass. Its ends terminate suddenly in the oesophagus and intestine respectively, the latter end being easily recognisable by the junction of the malpighian tubes (see plate I, figure 23). Beginning at its outermost surface we have first the ramifications of the air vessels ; next a series of parallel bands of annular and of longitudinal muscular fibies, crossing each other at right angles and leaving square interstices (which b 2
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