TESTING THE VALUE OF FUMIGATING AGENTS 315 



stopper of wood, which fits tightly into one of the holes in the side 

 of the box mentioned above, in such a manner as to support the cage 

 inside of the box with the long axis of the cage at right angles to 

 the wall through which it projects, in which position it is maintained 

 by the wooden stopper. It will be seen that the stopper does three 

 things: it closes the open end of the netting cage, preventing the 

 escape of mosquitoes or other insects which may be inclosed in the 

 cage, stops the hole in the wall of the box through which the cage 

 is introduced, and keeps the cage in position. 



Mosquitoes placed in cages, which in turn are suspended from the 

 wall of the box in the manner above described, are freely exposed to 

 whatever may be present in the air within the box, because the gases 

 or fumes pass freely through the wire gauze of which the cage is 

 made; at the same time, the insects are imprisoned in the cages, 

 and are available for close examination at any time merely by remov- 

 ing the stopper, which in turn removes the cage to which it is attached. 



The hole occupied by the stopper and cage is closed by a sim- 

 ilar stopper, when the cage is removed, thus preventing the escape 

 of gases. Inasmuch as one may replace the cage by a blank 

 stopper in a very few seconds, the loss of fumigating material is 

 minimal. 



Glass windows are provided in opposite sides of the box. These 

 permit a limited examination of the contents of the box until the 

 fumes become too dense. The relative amount of light coming 

 through, observed at the windows of the box as fumigation progresses, 

 furnishes a rough index of the volume, or rather density, of the 

 fumes at any time. Hooks are provided in the interior of the box, 

 upon which may be hung various fabrics ; or one may place fabrics 

 over the cages in such a manner as partially to shield the cages 

 containing mosquitoes from the action of the fumigant. 



In addition, a lamp (alcohol) with a long neck has been used 

 to furnish heat or flame for any substances requiring the addition 

 of heat aside from that produced by the combustion itself. The 

 lamp is supported by a stopper which fits tightly in one of the holes 

 in the bottom, through which the cages are introduced, and one 

 may remove the lamp as one replaces the cages by removing the 

 stopper, which withdraws the lamp, and substituting a blank stop- 



