28o The Control of Mosquitoes 



one at every inspection. House tenants hid 

 containers, and cotild never understand why an 

 inspector who had missed a container one day 

 always came in search of it the following day. A 

 small acetylene lamp or an electric flash lamp 

 was used to determine the presence of mosquito 

 larvae in large containers in dark places. 



The non-immune residence sections were located 

 in three limited areas, and especial care was taken 

 in these localities. Most of the Americans in 

 Panama in 1905 were employed by the Isthmian 

 Canal Commission, and the greater part of them 

 worked in what was then known as the "Canal 

 Building," which occupies an entire block and is 

 three stories high. Naturally, this building, if 

 it contained infected mosquitoes, would become 

 an important focus for the spread of yeUow fever. 

 To prevent such an occurrence, two inspections for 

 water containers were made weekly, and the entire 

 building was fumigated once every fortnight. It 

 was found that the screened doors' leading onto 

 the verandas were propped open or held open by 

 the janitors, and that mosquitoes actually gained 

 access to the building through these doors. In 

 order to prevent this, the department of sanita- 

 tion placed a lock on each veranda door, and kept 

 them locked, with the keys in charge of one re- 



