PROPHYLAXIS OF MALARIA. 
77 
mixture was successfully used by troops when on marches in the 
Philippines. 
For use, as a temporary measure, a mixture of oil of citronella 
and vaseline, when smeared upon the skin, is very serviceable and 
is not unpleasant. If liquid vaseline is used, about one part of oil 
of citronella should be mixed with six parts of liquid vaseline and 
applied frequently when exposed to the bites of mosquitoes. If 
liquid vaseline can not be obtained ordinary vaseline may be used, 
a teaspoonful of the oil of citronella being mixed with two ounces of 
vaseline. 
It is obvious that the use of substances that are only temporary 
in their protective power and that depend entirely upon the will of 
the individual for what success they may have, are not of any great 
value in the prophylaxis of malaria in the military service. Such 
methods are miserable makeshifts and should be rendered unneces¬ 
sary by the adoption of more scientific and valuable ones. 
The value of screening and the use of the mosquito net has been 
abundantly proven by practical experiments, beginning with that of 
Sambon and Low. These investigators, in order to test the truth of 
the theory that the malarial infections are transmitted by mosquitoes, 
spent an entire summer at Ostia, a most malarious region in the 
koman Campagna, residing in a mosquito-proof hut. During the 
day the time was spent mostly out of doors, but early in the after¬ 
noon the observers retired to their hut and there spent the night. 
Neither investigator developed malaria, although it was said, by the 
natives, that to spend one night in that place would result in a 
malarial paroxysm, and most of the inhabitants who were not pro¬ 
tected by screens developed the disease during the summer the ob¬ 
servers spent there. 
Of the notable instances of the protection from malaria afforded 
by screening may be mentioned the experiments of Procaccini, in 
Sardinia, and of Tzuzuki, in Formosa, with military troops; and in 
the Canal Zone, in the settlements of Gatun and New Gatun, as re¬ 
ported by Orenstein. 
Procaccini, 37 in Sardinia, reduced the number of cases of malaria 
among the soldiers from 70 per cent to 57 per cent, in one season, 
by screening the barracks, and later the percentage was reduced to 
less than 20 per cent. 
In Formosa, Tzuzuki 3S tested the efficiency of screening by select¬ 
ing 115 soldiers of a battalion stationed at Kirun, a most malarious 
locality, and furnishing them with screened barracks, the remainder 
of the battalion being unprotected from the bites of the mosquitoes. 
The 115 soldiers were thus protected from September 21 to De¬ 
cember 8. the malarial season, and not a case of the disease developed 
among them, while, in the same time, among the 750 soldiers not so 
