Gr. H. F. Nuttall 
181 
(1915, p. 72) states that lice survive 28 hours’ immersion; 10 lice were 
placed in water at 6° C., and were removed and dried at intervals; 
seven of the insects survived after 4 successive immersions lasting 14, 
22, 5, and 14 hours respectively, whereas all the lice placed in water 
at 30-37° C. were dead in 14 hours. Finally Galli-Valerio (1916, p. 41) 
records that lice were dead after immersion periods of 24 hours at 20° C., 
and of 72-96 hours at — 3 to 1° C. 
I would record a few experiments of mine bearing on the problem: 
Expt. (a) hi. 1917. Corporis larvae, immediately after hatching, 
were placed on a piece of cloth in bottles that were completely filled with 
water and tightly corked, bubbles of air being excluded. 
After 19 hours at 9-10° C. of 10 larvae 9 were dead and 1 alive but 
feeble. 
After 18 hours at 9-10° C. of 11 larvae 9 were dead, 1 feeble and 
1 lively. 
Expt. ( b) hi. 1917. Corporis eggs that had been laid on hair or 
cloth, were similarly immersed in water at ca. 10° C. The eggs tested 
were at different stages of development, i.e. 0-7 days old, having been 
maintained at 30° C. in the thermostat. After immersion, the eggs 
were dried and returned to the thermostat at 30° C. 
Age of eggs 
(at 30° C.) 
Immersion 
period 
Result 
under day 
48 krs 
9/13 
99 
96 „ 
2/12 
3 days 
48 „ 
14/15 
4 „ 
24 „ 
14/16 
71-4 % hatched 
6 „ 
24 „ 
12/17 
6 „ 
48 „ 
11/18 
7 „ 
24 „ 
18/21 
Controls 
29/48 
5/8 
7/7 i 
7/9 V 61-2 % hatched 
13/31 
6/9 
4/4 , 
The fractions denote the number of eggs from which larvae emerged, thus 9/13 
indicates that 9 out of 13 eggs hatched normally 
The result may appear paradoxical in so far as a higher percentage 
of eggs hatched from among those that were immersed than from 
among the controls. This is doubtless attributable to the moistening 
the immersed eggs had received; the controls having been kept con¬ 
tinuously in a dry atmosphere. It will be noted that but 2 out of 12 
eggs hatched after immersion for 96 hours. 
These results have a practical bearing since they demonstrate the 
futility of attempting to destroy lice in infested garments by soaking 
them even for 96 hours (at ca. 10° C.), for some eggs may survive the 
12—3 
