574 
Combating Lousiness 
minute or two at this temperature or 10 minutes at 55° C. They are killed 
instantly by moist heat at 80° C. or over. In a steam disinfestor that 
has been properly packed and managed the exposure period need not 
usually exceed 15 minutes (pp. 429-435). 
The various forms of apparatus employed for the destruction of 
vermin by dry heat and steam are described, leading up from the simplest 
to the more complicated. Special stress is laid on improvised methods 
devised by medical officers from materials at hand, no apparatus being 
available, or when many of the forms of apparatus employed success¬ 
fully in peace times had for various reasons failed to meet the exigencies 
of war (pp. 435-450, 454-466). The main source of failure in the regular 
disinfecting machines is due to their being primarily designed to destroy 
the causative agents of infective diseases according to bacteriological 
standards, coupled with their altogether too small size. The number of 
articles that require to be treated when lice have to be destroyed on the 
clothing of vast numbers of men demands the use of larger apparatus. 
For louse destruction on a large scale, but two methods commend 
themselves, i.e. hot-air and steam disinfestation. Huts built of cheap 
materials, according to some of the plans herein described, may be used 
for this purpose (pp. 441-450, 459-461). The huts can be built of 
different sizes to meet various requirements. Railway vans may be used, 
the number of these being multiplied in accordance as they are wanted 
(pp. 461-465). 
Stress is laid upon the need of standardizing the load of effects intro¬ 
duced into the disinfestor or disinfector. The effect of steam and hot-air 
disinfestation on clothing is discussed and the advantages of hot air over 
steam stated. Given the choice, either of these means are greatly to be 
preferred to sulphur fumigation (pp. 474-481). 
The methods of recording the temperature in the disinfector chamber 
are briefly considered and a simple and useful method employed in France 
described (p. 481). Common causes of failure in disinfestation are pointed 
out in some detail because so frequently recurring and vitiating the 
results obtained in practice (p. 482). 
Insecticides and remedies employed against lice, together with their 
mode of action and application, are considered. It is concluded that 
so-called repellants exert their chief effect on lice by virtue of their 
being primarily insecticides; they do not prevent hungry lice from biting 
man. 
Surveying the list of remedies for lousiness and the evidence in favour 
of their usage (pp. 519-558, Nos. 364-474) supplied by experiments 
