502 
Combating Lousiness 
Widmann (18. vm. 1915, pp. 289-298) relied on the stoppage of 
intestinal peristalsis in lice as evidence of the insects’ death, but he was 
wrong in doing so (see this volume, p. 183), and I therefore exclude his 
experiments from the table. He experimented with only 2-4 nits with 
each vapour without mention of control nits to prove that they were 
fertile; therefore only his negative results are cited. 
Wulker (1915, p. 628) relied upon the movements of the embryo in 
the nit as a sign of death, this being a test of very doubtful value. In 
common with many authors, he does not state how he determined that 
the lice were actually killed. 
Teickmann (1917) placed lice and nits in glass dishes wrapped in 
cotton wool (the parcel was put under bedclothes in one experiment), in a 
well sealed room of 2120 cb. ft. capacity treated by hydrocyanic acid gas. 
Baumgarten (1917) exposed lice (and nits?) to saturated naphthaline 
vapour delivered by a tube from a retort into a small iron lined box and 
killed the insects in 10-15 minutes at 40° C. This constitutes his “new 
method” which need not detain us further. 
Zupnik (iv. 1915, p. 371; v. 1915, p. 565) made his experiments in 
10 cm. long test-tubes, the insecticide being placed on a linen strip 
near the cotton plug, the lice upon a linen strip at the bottom of the 
tube. Some experiments were conducted differently as specified in the 
table. 
Experiments, by various authors, in which sham death does not appear 
to have been excluded, are omitted from the table. 
Eef. 
No. 
Vapour or 
gas tested 
At ° C. 
Stage 
tested 
n. = nits 
1. =lice 
Result 
+ = killedin '=mins. 
±=some killed in " = secs. 
O = survived exposure of 
Authority. 
See key to 
refs, at end 
of table 
110 
Acetic acid 
4-3 vol. % 
1. 
+ 5 hrs 
K.-L. 
111 
IM „ 
— 
1. 
+ 8' 
>> 
112 
— 
n. 
O 5 days 
Zu. 2 
113 
Acetic acid and ether 
— 
— 
n. 
O 1£ hrs 
114 
Ammonia 
3-2-5 vol. % 
— 
i. 
O 6 hrs 
K.-L. 
115 
J J 
11-1 
— 
i. 
± after some hrs 30 % 
killed 
5 J 
116 
„ (25 % sol.) 
— 
— 
i. 
4- 2' (in test-tube) 
P. 
117 
— 
— 
i. 
4- 1 hr 
F. 
118 
— 
— 
i. 
O after some hrs 
Zu. 1 
119 
Amyl alcohol 
Anisol 
— 
— 
i. 
O after some hrs 
120 
1/20 c.e. per 2 L. space 
16° 
i. 
O 20', only immobilized 
L. 
121 
33° 
i. 
± 12', 60 % survived 
» J 
122 
— 
— 
i. 
± 10', mostly killed, some 
recover in 24 hrs 
Fr. 
123 
— 
-' 
i. 
O 13J' (23 insects) 
B. & B. 
124 
— 
— 
i. 
± 26', 4/6 survived 
55 
125 
— 
— 
i. 
± 30', 8/12 „ 
55 
126 
— 
— 
i. 
4- 45' 
F. 
Zu. 2 
127 
— 
— 
n. 
O 3 hrs 
