184 Biology of Pedicuius humanus 
of poisons. Lice dipped in water at 70° C. are killed and soon turn pink 
and then red. 
Lice may die simply from overfeeding without any rupture taking 
place. Apparently deaths due to this cause have also been observed 
by Fantham (1912, p. 513) and Heymann (18. vm. 1915, p. 307). 
In practice it is best to rely on the unequivocal signs of death 
afforded in (a) nits by the complete collapse of the shell, the contraction 
of the contents into a small space, the change of colour (whitish, when 
coagulated as by boiling, or brownish, when heated dry) and (b) the 
shrivelling up and growing brittle of larvae and adults, their change of 
colour (whitish when boiled, brown or blackish when dry). 
Natural Enemies and Parasites of Lice. 
(a) Enemies. 
The chief enemy of lice is modern man who is gradually awakening 
to the full significance of these ancient parasites of the human race. 
That many primitive peoples are constantly at war with lice is well 
known; their efforts may be more or less spasmodic but at times they 
are fairly well organized though simple as depicted in the accompanying 
illustration (Plate III) showing an active campaign proceeding such as 
I have beheld in Mexico, Italy, Spain and North Africa, without the 
descending scale of actors being so perfectly adjusted. 
Among the lowest races of man, the monkey-like manner of dealing 
with lice has persisted. Thus Denny (1842, p. 18) writes '‘we are told 
that the Hottentots and other nations in West Africa, as well as American 
tribes, eat them, they and their wives collect them and have hence 
been called Phthirophagi." Dr Richardson informed Denny that 
during the overland expedition under Sir J. Franklin, he “daily observed 
the Indian women cracking their parasites between their teeth with 
much apparent enjoyment.” Blanchard (1890, p. 439) states that this 
habit prevails among the Aleutians and Hottentots (fide Sparmann) 
and Australians (fide Labillardiere) who thus destroy capitis. 
Baboons as louse catchers were extensively used in Lisbon in the 
eighteenth century, the animals being hired out for the purpose of 
catching and eating the redundant capitis. 
Ants may also claim the distinction of natural enemies of lice. 
Gaulke (1863) already mentions them as louse exterminators, and Hase 
(xi. 1915, p. 158), who refers to this author, states that German soldiers, 
when heavily infested, reduced their louse population by placing their 
