Gr. H. F. Nuttall 
501 
Experiments wherein corporis were exposed to various 
vapours and gases. 
(a) Experiments in vitro or in boxes. 
Notes on methods employed. Authors, other than those specified 
below, do not state how they performed their experiments unless this 
is mentioned in the table. Most authors fail to mention the temperature 
at which they tested the insecticides, this being a serious omission since 
temperature exerts a great influence on vapour tension. Reports on 
experiments which do not state the conditions are practically valueless 
for they fail to give even an approximate measure of the concentration 
in which the insecticide was employed. A number of highly defective 
observations (Frankel, hi. and iv. 1915, etc.) are therefore omitted 
from the table, although some very crude observations are recorded. 
Knaffl-Lenz (1915, p. 708) placed lice on cloth in 100 c.c. tubes 
corked at both ends. Fine tubes passing through corks in the ends of 
the larger tubes admitted a known concentration of pediculicide vapour 
from an adjoining flask in which the insecticide was heated. 
Legroux (1915, pp. 470-473) exposed lice to vapours in 2 litre 
belljars, the insects being placed on muslin on one side and c.c. of 
the insecticide upon the other side within the vessel. The lice were 
observed for 1-20 hrs, and were regarded as dead if they remained 
motionless on one spot. Legroux notes that some lice recovered after 
1-20 hrs where the exposure was short. He tested the vapours at 16° 
and 33° C., these being temperatures recorded in clothing. 
Nuttall (unpublished experiments, 1915) placed nits laid at most 
24 hrs before (on cloth or hair) upon little metal benches resting in 
circular glass dishes, measuring 5 cm. across and 2 cm. in depth, which 
contained an insecticide that had been poured in to a depth of ca. J cm. 
The bench surface stood about | cm. above the surface of the fluid 
whose evaporating surface was uniform throughout the series. The 
dishes were covered with glass plates so that the space was saturated 
with vapour at ca. 15° C. Unexposed fertile eggs of the same lot served 
as controls for each experiment. 
Report (1915, pp. 53-58) relates to Russian experiments made 
(a) with various vapours of reagents of which 15 drops were placed on 
cotton hung 4 inches above open glass dishes containing lice, ( b ) with 
different powders. As the available review of the Report does not state 
if the powders were brought in contact with the insects or not, these 
experiments are not mentioned in the subjoined table. 
