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 ac- 
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. 
Ts 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 
L 
