SCIENCE AND PRACTICE 3 



1000. In 1885 it was over 70 per 1000. The work was 

 abandoned. In May 1904 Colonel Gorgas and his forces 

 took possession of the canal zone. This is a zone of 

 territory running fifty miles north and south, with a good- 

 sized town Colon at one end of it and another 

 Panama at the other end of it. Many hundreds of men 

 were at once organised and set to work to destroy in both 

 the towns the Stegomyia gnat. This was effected by doing 

 away with all the breeding-places of the gnat, that is, 

 screening and covering every water receptacle in the 

 town, so that the gnats or mosquitoes cannot breed. 

 Then a fumigating process was carried out in all houses 

 and buildings, great and small, to destroy such gnats as 

 were still alive. No less than 200,000 Ib. of pyrethrum 

 and 400,000 Ib. of sulphur were used in this fumigation. 

 In December 1905 the last case of yellow fever occurred. 

 It took sixteen months of the work just described to 

 effect this. 



In a different way the Anopheles gnat or mosquito, 

 which carries the germ of malaria from man to man, was 

 got rid of. This gnat breeds in clean water, where grass 

 and weeds grow ; it belongs chiefly to country districts. 

 As it rarely flies more than 200 yards it was sufficient to 

 destroy the breeding pools within that distance of the 

 workmen's houses, camps, and villages. All the windows 

 and doors of all houses were fitted with wire-gauze 

 screens, which prevent the entrance of the gnats, and the 

 population was furnished with quinin, a dose of 3 grs. a 

 day being ordered to bring the men into such condition 

 that the malaria parasite would not thrive in the blood 

 even if introduced. 



The object with which Colonel Gorgas and his associ- 

 ates started was accomplished in less than two years. 

 The control of yellow fever and malaria has become even 

 more complete in the two years which have followed. It 



