Annual report of the Board of Regents of the Smithsonian Institution . ch isby far the most redoubtable; then A. pseud-opictus^ A. superpictus^ A. hifurcatus^ , and finally a last species, Pyreto-phorus costalis. The proofs which one can give to-day ofthe mosquito theory are three. The first isthat of Grassi, who, in 1898, in associationwith Bignami and Bastianelli, was able tofollow the evolution of Plasmodiurn day byday in the bodies of mosquitoes which hadbeen made to suck blood ajffected by ma-laria, showing thus that the parasite couldpenetrate the insect, remain there a certain
Annual report of the Board of Regents of the Smithsonian Institution . ch isby far the most redoubtable; then A. pseud-opictus^ A. superpictus^ A. hifurcatus^ , and finally a last species, Pyreto-phorus costalis. The proofs which one can give to-day ofthe mosquito theory are three. The first isthat of Grassi, who, in 1898, in associationwith Bignami and Bastianelli, was able tofollow the evolution of Plasmodiurn day byday in the bodies of mosquitoes which hadbeen made to suck blood ajffected by ma-laria, showing thus that the parasite couldpenetrate the insect, remain there a certaintime, and then leave to pass immediately toman. These students have also establishedthe fact that while in the Anopheles^ thehaematozoan undergoes profound transformation, constituting a veri-table evolution, and that the intimate mechanism of the transmissionwas as follows: The parasites sucked in with the blood lay eggs in thestomach, which eggs encyst themselves in the walls of the stomach, andproduce a multitude of little vermicular spores. These, set at liberty. Fig. 2.—Head of a mosquito.(After Neveu - Lemaire.) ; p, maxillary pal-pfe; a, antonna?. 706 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1909. by the breaking open of the cyst, are carried by the blood toward thehead, then into the proboscis of the insect, which inoculates them withevery bite. The second proof is this: One can voluntarily producemalaria by causing healthy individuals to be bitten by Anophelesintentionally infected. This experiment was carried out by PatrickManson on his own son. The third proof is as follows: Malaria canbe avoided by taking the single precaution of protecting ones selffrom the bites of mosquitoes. This results from the experiments of Sambon and Low, who, with-out the least accident, were able to pass an entire summer in one ofthe most insalubrious places of the Roman campagna, by simply cov-ering the openings of the house with wire netting of sufficiently finemesh to preven
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