536 THOMPSON YATES LABORATORIES REPORT 
2. Shallow muddy natural pool (about six by three feet) below lower 
corner of Baptista Campos. Larvae scarce ; a case of tertian 
fever was examined which came from a house not far distant. 
3. Tiny natural puddles at the S. Jronymo end of Trav. 3 Maio ; some 
of the occupants of the surrounding houses stated that there was 
' much fever,' but no cases were actually examined ; search for 
adults in some of the houses not successful. 
4. Wheel track puddles of muddy water near house of Senor M., beyond 
Marco da Legua. A man was taken ill, in a hut a few yards 
away from the puddles, and shewed tertian parasites in his blood. 
At Manaos. 5. Wheel track and natural puddles at Cachoeirinha, Manaos ; all 
shallow and muddy, without green growth, but extending here 
and there into the grass (rainy season). This region has the 
reputation of being the ague locality in Manaos : it consists of a 
comparatively high-lying plateau away from ' swamps,' and, in a 
general way, does not look like a fever stricken place. On this 
plateau of a few acres extent, large numbers of Anopheles argyri- 
tarsis larvae and pupae were readily collected. One point of 
interest is that a few individual larvae were found in the pools on 
the course of what becomes a miniature torrent during a rain 
shower, and carries the water down to the igarape (stream) 
some fifty or sixty feet below ; from the steepness of the descent, 
and the small size of the puddles, and the direct evidence of 
drainage from Anopheles puddles on the edge of the plateau, it is 
most likely that these isolated single larvae were carried down 
from above. 
From what has been said it appears that this species favours small very shallow 
pools ; these consisting of opaque muddy water, and freedom from growth makes 
the larva a very conspicuous object to inspection. The small size of the pools makes 
them eminently suitable for filling in or for treatment with kerosene, etc., and whenever 
pools or collections of water were met with in or about the city they were always 
inspected, and often netted also, but the above-mentioned places alone yielded larvae ; 
pools that were only observed once may have been temporarily in abeyance. 
Dr. Furness, of Bahia, told me that he had met with the larvae (of the same 
species) in the ' ant-guards ' in gardens. In Para I did not meet with any in these 
water collections, although in one garden adult insects were met with and a natural 
breeding place was found not many hundreds of yards away {B. campos). Nor, 
again, were larvae discovered in swampy and overflowed districts in the forest and 
outskirts of the city. During the prolonged operations for laying a fresh tramway 
track there was much water lying about in the Estrada da Independencia for months, 
but these pools were not affected by Anopheles. 
