304 The Control of Mosquitoes 



of a man at Colon who had never been to Matachin. 

 However, the agent remembered distinctly having 

 been bitten about the ankles and wrists while 

 checking freight in cars that arrived from Colon. 

 This is a characteristic biting habit of Aedes 

 calopus. Subsequent investigation showed that 

 these cars had been located on a siding at Colon 

 near the house in which the case of yellow fever 

 had occurred, corresponding exactly as to time of 

 infection with the case at Matachin. 



At the time the yellow fever epidemic was 

 coming to an end, the sewer system, water supply, 

 and paving of the city of Panama were well under 

 way. The old theory of the upturning of the soil 

 being responsible for yellow fever was still believed 

 by many. There was not a single case of yeUow 

 fever in the houses on or adjacent to the streets 

 being torn up, nor in streets where trenches 

 were being dug. Although the main water sup- 

 ply distribution system was installed before yellow 

 fever was eradicated, it had but little effect upon 

 the suppression of this disease. Few houses 

 were at that time supplied with plumbing fix- 

 tures, and the native population preferred 

 rain water, to which they were more accus- 

 tomed. In subsequent years, as the houses be- 

 came supplied with plumbing, less rain water 



