A practical confirmation of the mosquito the ory resulted from the labors of Low, Celli, Grassi, and the Red Cross of Italy, which demonstrated ;n 1901 that the use of the mosquito-net and the draining of stagnant pools prevented malaria in individuals living in notoriously malarious coun tries. Covering the surface of stagnant water with a pellicle of crude petroleum suffices, in many instances, to kill the lame of the mosquito and decrease of malaria follows. A solution of permanganate of potash. one to 1500, was found to be as effective. though not as cheap, as pe troleum. It has been ascertained that goldfish may be used as the agent for the destruction of the larva' of mosquitoes, as they cat them eagerly.
Extensive and important studies in New Jer sey established the facts that the most abundant species of mosquitoes in that State, t'ubx sot iicitans, breeds not only in brackish and salt water. but also in water that is 25 per cent. more salty than ordinary sea-water; that it dues mud breed in fresh water at all; that adult mosquitoes may be found in great abundance from 20 to 4(1 miles from their breeding-places; and that mosquitoes occur from 5 to 15 miles oft shore, over the Open ocean. at points to which they have been carried by the wind. Ca/cx /ma gi as, next in abundance to ('alex sollieitans, was found breeding in every place where water is not salt. The breeding time for these mosquitoes is late in the fall. and the adults hibernate.
In the opinion of the expert observers who have investigated the matter, the mosquito is also responsible for the transmission of yellow fever. This theory was first advanced by Dr. Carlos Finlay. of Ihavana, in 1381. Reed. Carroll. .Agra motile. and Lazear, who formed the commission appointed in 1900 by the Surgeon-General of the United States Army to investigate yellow fever in Cuba. concluded that the mosquito serves as the intermediate host for the, parasite of yellow fever and that it is highly probable that the disease is propagated only through the bite of this insect. Calcx fascialus, which is identical with Cabr tiniads (Giles), is the mosquito that acts as host for yellow fever. No less an author ity than Dr. John GuitC.ra A, formerly an oppo nent of this theory of the transmission of yellow fever. has become its earnest advocate. The mos quito has a part. also, in the dissemination of leprosy. I:aposi has instanced a case of this disease, easily traceable to a mosquito-bite. The experiments of .\lvarez. as quoted by Carmichael, support this theory of mosquito transmission in leprosy. It is admitted without reserve that filariasis is transmitted by mosquitoes. Cor roborative experiments and studies in the devel opment of Muria were made 1)3• Low. of 1901. found active Maria embryos in the thoracic muscles of Culex terrify ing between twelve and twenty-four hours after this mosquito had fed on a patient suffering from filariasis. In ('ubx faseiatus he found per fected filarix in the head, neck. and proboscis. Elephantiasis has been transmitted by the mos quito. Its parasite was found in their bodies by the investigations of the Liverpool School of Tropical Medicine in Nigeria, Africa, in 1900.
properly eliarged with the trans mission of many diseases. Nut tall fed the bacil lus of the bubonic plague to flies, and ascertained that they eon•ey the infection to man. Car michael believes that leprosy is communicated by the same insect. The bacilli of anthrax (malig
nant pustule) have been found in flies. Grassi, of Milli'. and, much biter, Beale, of Calcutta, demonstrated that cholera was a fly-borne dis ease. and the germs of typhoid fever are carried by same insect which swarms over faecal evacuations. ller•ieux. of Franee, ascribed the spread of smallpox to flies. Shnond's investiga tions. carried on during 1599. together with the cults obtained by Mersin, favor the theory of the spread of plague from rat to man by the flea. Bieck charges the it eh- in it e (q.v.) with being an active agent in the spread of leprosy. Smith and Kilbourne established the fact that the tirk propagates Texas fever sheep. The bacilli of anthrax have been found in earth Minns.
Kobler's experiments led him to accuse the ant of carrying the infection of bubonic plague to man. From a sheep that died I if anthrax, in Cyprus, in 1901. ants transmitted the fatal dis ease to a woman in a cottage near by. Roaches arc believed to carry typhoid fever in the saine as do flies. The bedbug is responsible for the spread of leprosy (Carmichael), cancer (Moran]. tuberculosis (Denevre), and relapsing fever (Titkin).
Insects. it is seen, propagate diseases in two (1) As bringing infection to a wound or to food and drink on the surface of their bodies, after crawling over an infected spot. or bringing the infection in the form of bacilli in their intestinal tracts; (2) as inter mediary hosts, bringing to the victim the infec tion in the fluids of their bodies and inflicting wounds through %Odell the poison is introduced into the body of the victim. The mosquito is a true intermediary host. Flies and liens are examples of carriers. Coplin, of Philadelphia, experimenting in the line of the researches of fsangrs. caused roaches. flies, and bedbugs to walk over cultures of various disease germs and then to walk over sterile agar plates, many hours later, having been kept in the meantime in large jars, under as natural conditions as possible. Examinations of the agar plates made subsequently showed active cultures of the va rious bacilli of infection. The feet, the ventral portion of the body. and the wings of insects carry infection and plant the disease organisms in rows and small colonies throughout the sur face of the sterile plates. Forty-eight hours of continuous infectivity was shown in the ease of many disease germs thus transmitted. In one ease the typhoid bacilli carried on the body of a roach retained their virulence for ninety-six hours.
But one germicide has proved of avail in dis infecting bacteria-laden material, and this is formaldehyde. The great difficulty in rendering harmless the insect carrier of disease is easily appreciated.
Consult: floss, Malarial Fever: Its Cause, Prevention, and Treatment (Liverpool, 1902); Low, Papers on Malaria and Filariasis (George town, Demarara. 1901); Cornoldi, La mosca c it colcru (Venice, 1884) ; Beale, Cholera a fly Poole Disease (Calcutta. 1597); Moore. "Flies and Disease," in Medical Magazine (London, Is93-9.1) ; Howard, "Carriage of Disease," in Niscellancous Results (Washington, 1901) ; Na tal], Hygienic Measures in Relation to Infectious Diseases (New York, 18931; Grassi, Die Mala ria (Jena. ; Celli, Malaria According to the New Resf arches (London, 1901) ; Liverpool School of Tropical Medicine, Memoir III., Report of the Malarial Expedition to Nigeria (Liver pool, 1901).