72 
Lice and Disease 
fed upon an area measuring 1-5 cm. across on the back of the hand; 
no itching followed when they bit above the ankle. The small red areas 
about the puncture had mostly disappeared within half an hour. 
Swellengrebel (1916), who allowed lice to bite his arm, observed a slight 
hyperaemia lasting an hour at the seat of the bite, there being no 
itching. If, however, he crushed the louse whilst it was feeding, 
the spot became reddened, oedematous, itchy, and slight necrosis of 
tissue took place, the spot being visible for 14 days. He ascribed the 
bad effects attributed to louse bite to the crushing of the insects and 
the scratching of the part. Bacot (ii. 1917, p. 235) reported that louse- 
bites produced more irritation on his person than did the bites of fleas 
and bedbugs; he attributed the effect of the bite to the insect’s saliva. 
In this connection I may cite my own experience when raising 
capitis by the wristlet method. I had previously, on repeated occasions, 
allowed a few corporis to bite me and had observed only transitory 
effects on my arm, the small congested areas about the seat of the bite 
usually disappearing within half an hour or an hour. 
My Laboratory Assistant’s arm. having become so irritated from 
feeding many lice that the itching disturbed Lis sleep, I took over a 
wristlet (10. vi. 17) in which larvae had begun to emerge a day or two 
previously and undertook to raise 100 of the insects to maturity, this 
being duly accomplished. Only transitory effects were observed 
whilst the larvae were small, but shortly after the first adults emerged 
the bites began to produce more lasting effects. I nevertheless con¬ 
tinued to feed the insects on my wrist, the position of the box being 
shifted about every 12 hours. As, however, the irritation continued 
and increased, and the tendency to scratch the bitten arm became 
difficult to control, I finally shifted the wristlet to the knee on 26. vi. 17. 
Here the bites produced similar effects to those on the arm. 
The accompanying illustration (Plate I) depicts the inner surface 
of the forearm as it appeared, six days after the last use of the arm as 
a feeding ground. The irritation had already begun to subside. The 
arm shows three patches (A, B, C) where bites had been inflicted. At 
(A) the bites form a circular pattern due to the lice having fed but once 
through the floor of the box, the latter not having shifted during the 
feeding period, at (B) at least two feedings occurred, the feeding areas 
overlapping, whilst at (C) a succession of about six feedings took place. 
At (A) the louse rash appears as a number of discrete conical elevations 
or papules, a few being confluent; these elevations were best seen by 
oblique light and could be felt by running the hand over the arm; the 
