MALARIA AND MOSQUITOES 89 



away from the waterside; but in this respect they 

 were little better than the Elizabethan sailors, who 

 considered that " miasmas " and "low fevers" only 

 attacked those living in lowlands or near streams, 

 and that to " live high " was the sure course to 

 safety in dwelling in tropical lands, whether the 

 Americas, the West Coast of Africa, o: India, were 

 their destination. 



Though they were not possessed of the scientific 

 advantages of modern times, these Elizabethan 

 sailors were shrewd observers, and there was much 

 truth in their ideas that living away from streams 

 and marshes largely destroyed the liability to attacks 

 of "ague" and "low fever." From the modern 

 point of view, let us examine their conclusions. 



Imagine a swamp, such as those investing the 

 mouth of the Amazon to-day, or that was present 

 in the Panama Canal zone ten years ago, or that 

 exists in many an Indian district at the present time. 

 A pool of water, warmed constantly by the hot sun 

 in daytime and with little cooling at night, is edged 

 with soft black mud, rich with the dead and decaying 

 remains of countless generations of vegetation which 

 surrounds its margin. Here and there a mangrove 

 thicket reaches the water, and the roots, forced under 

 these circumstances to reach the air, stand up as 

 aerating ridges above the foetid mud. A low " hum- 

 ming " or " buzzing " fills the air, and soon the 

 observer sees numbers of gauzy-winged insects flying 

 near the edge of the pool, and finally remaining, 

 almost motionless, on the surface of the water. 

 These insects, if captured, are found to be mosquitoes 



