418 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1919. 
vestigations of the dry-cleaning processes it was found that the entire 
process gave complete control of vermin, but that gasoline treatment 
alone was not a perfect control. This discovei'y led to a long series 
of important studies of the effect of various densities of oils on insect 
eggs. At the request of the Chemical Warfare Service various sub- 
stances and impregnated clothes devised for the protection of sol- 
diers against gas were also tested as to their effects upon vermin. By 
a special request of the electro-therapeutic branch of the Office of the 
Surgeon General of the Army, investigations were made of a high- 
frequency generator as a control means against the body louse, and 
as a result of these investigations suggestion was made as to the pos- 
sible application of high-frequency electric treatment for the control 
of scabies and other skin-infecting parasites. Cooperative investiga- 
tions along this line are about to be taken up. 
Among other problems investigated were the size of the meshes 
in mosquito bar necessary for the protection of cantonment build- 
ings from disease-carrjdng mosquitoes; reports on the insects likely 
to be found injurious to troops sent to Siberia; investigations of the 
protective qualities against lice of furs dyed in various colors, and 
so on. 
A series of lectures dealing with important sanitary problems from 
the insect side were mimeographed and were sent to persons in the 
Army, Navy, Public Health Service, and in civil life who were 
preparing themselves for or who were actively engaged in sanitary 
entomolog3^ 
Aside from this extensive cooperative research, entomologists were 
actually used in the Arm}-, a number of them being given commis- 
sions while others acted as noncommissioned officers, assisting in the 
camp work on the control of insects that carry disease. The commis- 
sioning of expert entomologists for this kind of work was difficult, 
owing to the organization of the Army, but had the war continued, 
it is safe to say more and more entomologists would have been em- 
ployed in this important work, whether commissioned or not. The 
records made by a number of these men were admirable and met with 
well-merited praise in Army circles. In great concentration camps 
in several instances entomologists were placed in entire charge of 
matters of mosquito and fly control under medical command or 
under sanitary engineers. 
In addition to this cooperation with the Army itself, the Bureau 
of Entomology also cooperated with the Public Health Service, 
which had the extremely important work in charge of the health con- 
trol of areas immediately surrounding the concentration camps, and 
held itself ready to assist in this work whenever called upon. 
