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Derris cream was prepared from a solution of derris extract in 
castor oil emulsified to make a cream containing 1 percent of rote- 
none and 7 percent of derris extract. The dosage ranged from 0.5 
drachm for a ohild with short hair to 2 drachms for a woman with long, 
thick hair. This was enough to cover the whole scalp and saturate 
the hair. The head should be washed every day for 10 days after treat- 
ment. Successful results were obtained, live lice or eggs having 
been found after treatment sometimes in less than 2 percent of the 
cases and always in less than 9 peroent, except in a group of evacuees 
from a Mediterranean country who refused to cooperate in hostels in 
London. No ill effects or discomfort' were caused to large numbers of 
volunteers by the applications of this derris cream. This cream, 
lauryl thiocyanate, and Lethane 384 Special were found to have great 
advantages over all others.— Busvine and Buxton (96) ; Anonymous (6). 
Lethane hair oil was recommended for the control of head lice 
as a result of laboratory and practioal trials made by a technioal 
oommittee at the instance of the Ministry of Health in London. From 
trials by the school medical services with this oil, or lauryl thio- 
cyanate, and with derris cream Glover oonoluded that the Lethane 
hair oil was the best* In limited trials by the committee creams of 
derris or cube were efficient, and cases of reinfestation were rare, 
but application was slow. Rotenone powders were effective and would 
probably be of value for treating patients who are too ill to be dis- 
turbed.— Great Britain Ministry of Health (245 ) • 
In Ontario a preparation of Lethane 384 Special and extracts of 
pyrethrum and derris were tested. All these, at various concentra- 
tions in deodorized kerosene, and derris extract in olive oil, quick- 
ly killed head lice and their eggs on school ohildren. The derris 
extract was effective at 0.5 percent of rotenone, and derris powder 
containing 5 percent of rotenone was also effective.— Twinn and MacNay 
(608) ; McLaine (386). 
The application of derris powder to louse-infested heads is a 
practical method of controlling head lice, and if persistently and 
generally applied should result in the eradication of lice from a 
community. The usual delousing methods do not destroy or remove eggs, 
and they do not prevent subsequent infestations. Derris powder, on 
the other hand, although not destroying or removing the eggs, re- 
mains on the hair long enough, under the best conditions, to kill all 
young as they emerge and, while there, prevents infestation from other 
sources. In the clinic of -the District of Columbia Health Department, 
3,056 treatments were given to 804 patients, of whom 406 were pupils, 
248 were home contacts, and 150 reopened cases. Absenoe from school 
on account of pediculosis can be reduced from weeks or months to a 
