X, B, 38 Barber et al.: Malaria in the Philippines 183 
Of course, the distribution as given in fig. 1 is true only in 
a very general way and takes into account only one factor: 
namely, the amount of decaying vegetable matter in the water. 
For example, seepage from small springs, or the overflow of 
wells, often fills animal tracks or small depressions in the soil 
with comparatively fresh water. Where exposed to the sun, 
these pools often contain many larve of A. rossii and of no other 
anopheles. It must be borne in mind, also, that where a species 
is very abundant it may overstep the limits commonly fixed where 
the numbers are only normal. Furthermore, in times of scarcity 
of water eggs may be laid in less preferred places. However, 
in both the dry and wet seasons we have found the distribution 
of A. febrifer comparatively limited, and we have not found it 
except where the water was kept comparatively fresh by a 
Small bayous from 
clear brooks 
and rivers. 


Fic. 1. The relative abundance of four species of Anopheles in habitats arranged according 
to the amount of decaying organic matter in solution in the water. 
spring or some flowing stream. We have frequently found larvee 
of mosquitoes other than anopheles in water contained in the 
axils of leaves, in upright joints of bamboo, or in coconut shells,. 
but never anopheles, although such occurrence of anopheles has 
been reported by others in the Philippines. 
Anopheles maculatus has been found in about the same sort 
of habitat as A. febrifer, but is far less common and apparently 
much more restricted to very fresh water. It has been found 
in localities at elevations of from 100 to 200 meters, such as 
Antipolo and a krook near Taytay, Rizal Province; Camp Stot- 
senberg, Pampanga Province; and Buhisan, Cebu Province; but 
it occurs near sea level at San Jose, Mindoro, and not far above 
sea level at Canlubang, Laguna Province. In Mindoro it was 
found among aquatic plants in a large irrigation ditch exposed 
to the sun. The larve from these patches of weeds were care- 
