X, B,3 Barber et al.: Malaria in the Philippines 187 
outer door open and keeping the inner door carefully closed. 
Twenty-two specimens of Anopheles rossii were caught in this 
vestibule at one time. It is worthy of note that nearly all of 
the mosquitoes caught in this vestibule were females containing 
blood, so they must have obtained their blood elsewhere and have 
been later attracted by the lights or people in the dormitory. 
Fewer visits were made to some barrios than to others, and 
the number of houses visited varies, so that Table I shows only 
approximately the frequency of anopheles in each locality, but 
the data for the proportion of the several species are more nearly 
accurate. No reliable data as to the length of flight of anopheles 
could be obtained in this region, since there was no barrio which 
did not have a possible breeding place within a few meters. The 
ground is comparatively open with few trees or underbrush to 
shelter mosquitoes or to retard their flight. 
In Table I are given data showing the amount of latent mala-- 
ria found in these barrios. The presence of malaria was deter- 
mined by the percentage of parasites found in blood smears. 
No intentional selection was made of the sick in obtaining 
samples. People of all ages were examined as they could be 
obtained. An examination of all persons in each barrio could 
not well be made, and the inhabitants of the different barrios, 
with the exception of Magbando, tend to shift more or less from 
one locality to another, so no very definite correlation between 
the mosquito fauna and the amount of indigenous malaria in the 
several barrios could be expected. Of the two barrios showing 
a relatively large proportion of Anopheles febrifer, barrios “J” 
and Magbando do not show a larger percentage of indigenous 
malaria than the other localities. However, Magbando contains 
a population that has long resided in a malarious region and may 
have acquired some immunity. Among the nine negatives, the 
blood of three showed indications of anzemia, possibly resulting 
from previous attacks of malaria. Barrio ‘J’ is a compara- 
tively new barrio, and as stated above exhibited a minor epidemic 
of malaria earlier in the season. The percentage of positive 
cases, however, was only 33.8, which is slightly below the aver- 
age of the whole population. Moreover two examinations at 
different dates were made of a part of the people of this barrio 
and all positives included in the percentage. The lower part 
of Mindoro barrio has many more breeding places than the up- 
per, and whether by coincidence or not, the lower streets showed 
a much greater amount of latent malaria than the upper. 
The proportions of sexes of the different species of anopheles 
and the proportion of females containing blood in the stomach 
