Mosquitoes and Parasite Problems. 143 



best suited to them. They are nature's miserable 

 castaways, parasitical tribes lost in a great dry 

 •wilderness where no blood is ; and every marsh- 

 born mosquito, piping of the hunger gnawing its 

 vitals, and every forest tick, blindly feeling with its 

 grappling-irons for the beast that never brushes by, 

 seems to tell us of a world peopled with gigantic 

 forms, mammalian and reptilian, which once afforded 

 abundant pasture to the parasite, and which the 

 parasite perhaps assisted to overthrow. 



It is almost necessary to transport oneself to the 

 vast tick-infested wilderness of the New World to 

 appreciate the full significance of a passage in Belt's 

 Naturalist in Nicaragua, in which it is suggested that 

 man's hairless condition was perhaps brought about 

 by natural selection in tropical regions, where he was 

 greatly troubled with parasites of this kind. It is 

 certain that if in such a country as Brazil he pos- 

 sessed a hairy coat, affording cover to the tick and 

 enabling it to get a footing on the body, his condi- 

 tion would be a very sad one. Savages abhor hairs 

 on the body, and even pluck them off their faces. 

 This seems like a survival of an ancient habit ad- 

 quired when the whole body was clothed with hair; 

 and if primitive man ever possessed such a habit, 

 nature only followed his lead in giving him a hair- 

 less offspring. 



Is it not also probable that the small amount of 

 mammalian life in South America, and the aquatic 

 habits of nearly all the large animals in the warmer 

 districts, is due to the persecutions of the tick ? 

 The only way in which a large animal can rid itself 

 of the pest is by going into the water or wallowing 



