A. Bacot and Gr. Talbot 
285 
As regards the moisture and temperature of the skin, some allowance is 
no doubt necessary for the individual periodic fluctuation of A. B. and G. T., 
but it does not seem probable that this could be of sufficient magnitude, 
especially under laboratory conditions, to greatly modify the results. 
Our conclusion is therefore that some allowance must be made for the 
greater attraction of G. T. over A. B., and that for practical purposes it is 
safest to assume that this ratio is more likely to be 3 to 2 than either of the 
extremes. 
XIII. SUMMARY OF RESULTS. 
For the purpose of testing culicifuges numbers of Stegomyia fasciata (the 
Yellow Fever mosquito), bred in incubators, were placed in cages kept in the 
laboratory. The efficiency of the preparations was tested by coating the 
forearm with a definite quantity of one or other of them and exposing in a 
cage, each test being controlled by inserting after a short interval the other 
and untreated arm in the same cage, the number of bites being compared in 
each case. By this procedure it was hoped to obtain a measure of the relative 
protection which the culicifuges might be expected to afford when used under 
practical conditions against Anopheles mosquitoes. 
In the first series of trials conducted within 15 minutes of application, 
eight preparations out of a total of 22 tested gave satisfactory results. Their 
active ingredients were (1) Oil of Cassia and Camphor, (2 a) Oil of Cassia and 
Peppermint, (5) Oil of Eucalyptus and Citronella with Phenol, (9 a) Crude 
Naphthalene (coke oven) and Camphor, (10) Crude “ Parasitox,” (15 a) Light 
Wood Oil, (21) Oil of Turpentine, (22 a) “ Lawson’s Anti-mosquito Compound.” 
These preparations were then tested to ascertain for what period their pro¬ 
tection could be depended upon. Preliminary trials indicated that this period 
was not likely to extend for more than two hours between treatment of the 
arm and exposure in the cage. None of the preparations gave complete 
protection in this series of trials; the most efficient were Nos. 1, 21, 2 a, 
15 a and 9 a, over a two hours period. 
It appeared, however, that the two experimenters were unequally attrac¬ 
tive to the mosquito. Making allowance for this, preparations 2 a, 1 , 15 a, 
and 21 were almost on a parity, followed by 9 a, 10 and 5 in order. A series 
of experimental trials based on this element of preference on the part of the 
mosquito was confirmatory of the factor of preference and showed a ratio of 
attraction of about the order of G. T. 3, A. B. 2. 
Observations on the behaviour of the mosquitoes during the tests suggest 
that the protection afforded does not result from a dislike of the insects to 
the culicifuge but to its obscuring the attractiveness of the human odour. 
Regarding the make up of the essential ingredients it was found that fluid 
preparations were inconvenient and tended to be wasteful in application. 
Soap preparations, unless very soft, are apt to be difficult of economic use and 
in either case are more readily dissipated bv perspiration than waxy or greasy 
