﻿IX, B. 5 Walker mid Barber: Malaria in the Philippines 393 



excess of water was first poured oflf. This was readily accom- 

 plished, as the larvse tend to swim against the current and collect 

 at the opposite side of the dish. The remainder of the water 

 with the larvae was then poured into the collecting jar. How- 

 ever, the method finally adopted as the most efficient was the 

 use of white granite-ware pans, about 20 centimeters long, 13 

 broad, and 5 centimeters deep, for dipping up the larvae. The 

 larvae were then removed from the surface of the water in the pan 

 with a large spoon, which for convenience was carried attached 

 to the finger or belt of the collector by a string, and were placed 

 in the collecting jar. This pan provides a larger surface for 

 skimming the surface of the water, while the corners are readily 

 inserted into small nooks. The larvae can be removed rapidly 

 with the spoon from the surface of the water in the pan with 

 a minimum excess of water. 



The collecting jar has usually consisted of a large wide-mouthed 

 bottle of heavy glass, holding about one-half to three-fourths of 

 a liter. One of these is attached to the belt of the collector by 

 a cord about the neck, leaving both hands free to manipulate 

 the dipping pan and spoon. On extended collecting trips it was 

 necessary to take extra jars, which were carried by a boy in a 

 hand bag. Occasionally these extra jars were replaced by a 

 large 5-gallon can with a handle, which served as a storage 

 receptacle for the larvae. 



Various methods were made use of to get rid of the excess 

 of water which accumulated in the collecting jars. One of these 

 consisted of a collecting can with an inner cylinder of fine wire 

 gauze provided with a bottom and extending above the top of 

 the can. This permitted the escape of the water without loss 

 of the larvae. Another method was to siphon off the water 

 from the bottom of the jar. The latter method accomplishes 

 the end without loss of the larvae if it is done from an undis- 

 turbed jar in which the larvae have collected at the surface. Two 

 pieces of glass tubing connected by a short section of rubber 

 tubing make a convenient siphon which can be carried in the 

 pocket of the collector. 



From our experience in this investigation, we wish to em- 

 phasize the advantages in experiments of this kind of collecting 

 very large quantities of larvae. Large numbers of the larvae fail 

 to develop and many of the adult mosquitoes die during the 

 course of the experiments; therefore, time and labor will be 

 saved ultimately if the collections of larvae be made on as ex- 

 tensive a scale as possible. 



