G. H. F. Nuttall 
99 
from verminous clothing and effects. It has long been known that 
stray lice may be picked up in public conveyances and railway carriages, 
particularly those that are upholstered and used by unclean persons. 
Like many others, I was always warned, when a child, against leaning 
my head against the backs of the seats, especially in some southern 
countries where capitis is prevalent. 
LOCOMOTORY POWERS OF LICE ON CLOTH AND HAIR. 
(a) On Cloth. 
When placed on cloth in a window, corporis will usually walk away 
directly from the light with more or less speed, according to the pre¬ 
vailing temperature, the degree of light, and the nature of the fabric. 
When it is cool, they progress more slowly than when it is warm, and 
they traverse a relatively smooth-surfaced fabric more rapidly than 
one from which numerous fibres protrude, having fewer obstacles to 
encounter in attaining their goal. It is due to these several factors not 
having been sufficiently taken into account that the locomotory powers 
of lice have not hitherto been appreciated. 
Several observers record the speed with which corporis may walk 
across a surface: Hase (1915, pp. 41-42, cited by Muller, 1915, p. 73) 
has apparently made detailed observations; he states that unfed lice 
walk more rapidly than those that have fed, and that large specimens 
walk faster than small. Over a horizontal surface of filter-paper, they 
walked a distance of 6-5-22-7 cm. a minute; their progress up an in¬ 
clined surface was somewhat slower, and beneath rough fabrics they 
averaged 10 cm. a minute; the pace when walking on dirty glass, 
leather, plastered walls, sand, etc., was also determined. Sikora (viii. 
1915, p. 533) placed lice upon cloth inclined at 80° and found that they 
walked upward a distance of 10-16 cm. in a minute. Peacock (1916, 
p. 42), without specifying the nature of the surface, saw two lice wander 
a distance of ca. 150 cm. in one hour, and he notes that lice have been 
seen to climb 90 cm. up the wall of a room. Gerwin (1915, p. 802), 
apparently impressed with the migratory powers of lice, suggests that 
wooden gutters filled with fluid should be placed on the floor about the 
beds of typhus patients. None of the foregoing authors mention the 
temperature at which their observations were made nor the intensity 
of the light to which the insects were exposed 1 . 
1 Galli-Valerio (9. v. 1916, p. 37) has published tracings showing the aimless meander- 
ings of lice upon a surface without stating particulars about the experimental conditions 
in respect to light and temperature, etc. 
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