46 THE POPULAR SCIENCE MONTHLY 



are ill for years from malaria, and their capacity for work greatly re- 

 duced, and they may finally die from some other trouble. 



Yellow Fever axd Mosquitoes 



As early as 1881, Dr. Charles Finlay, of Habaria, noticed a corre- 

 spondence between the abundance of mosquitoes and the prevalence of 

 yellow fever, but it was not until 1900, when our soldiers occupied the 

 island of Cuba at the time of the Spanish War, that experiments were 

 conducted proving that the disease is transmitted chiefly if not wholly 

 by a mosquito, Stegomyia calopus. The investigating committee was 

 appointed by Surgeon General Sternberg, and consisted of Messrs. 

 Reed, Lazear, Carroll and Agramonte. 



A small house was built and effectually screened against the en- 

 trance of all mosquitoes. A circulation of air was also prevented and 

 all sunlight excluded. A temperature of 76.20° F., with a moist air, 

 was maintained for sixty-three days — just the conditions favorable to 

 the spread of bacterial diseases. Moreover, clothes, blankets and bed- 

 ding which had been used by yellow fever patients and not cleaned 

 were put into the building and used by the inmates. Seven non-im- 

 munes were kept in this house, two or three sleeping in one room with 

 the contaminated bed-clothing, for about twenty nights, then shifts 

 were made and other subjects placed under the same conditions. All 

 seven were released from quarantine in excellent health at the end of 

 sixty-three days, not a single case of yellow fever appearing. Formerly, 

 contaminated clothing, bedding, etc., were regarded as a dangerous 

 source of infection and were usually burned. 



Another similar building was erected by these investigators and 

 was divided into two large rooms, one admitting air and sunlight 

 freely and containing the mosquitoes which had previously bitten yel- 

 low fever patients. In this room six out of seven persons bitten came 

 down with yellow fever. From the other room mosquitoes were ex- 

 cluded, and the occupants remained in perfect health. These tests still 

 more strongly confirmed previous experiments implicating the mos- 

 quito in transmitting yellow fever, and acting on this knowledge Gen- 

 eral Wood issued orders requiring the use of mosquito bars at the bar- 

 racks and for the destruction of mosquito lame in the breeding pools 

 by the use of petroleum. This work, in charge of Colonel Gorgas, was 

 carried out thoroughly, and continued until Habana was a compara- 

 tively healthy city. Mosquito extermination has everywhere been prac- 

 tised- — fumigating buildings with tobacco or sulphur to kill the adults, 

 and draining and filling the pools or applying oil to kill the larvae or 

 wigglers. Of 26,000 of these mosquito breeding places within the city 

 limits in March, 1901, only 300 remained in January, 1902. 15 More- 

 15 W. C. Gorgas, "A Few General Directions with Eegard to Destroying 

 Mosquitoes." Government Printing Office, "Washington, D. C, 1904. 



