368 RESEARCH IN PROTOZOOLOGY 



In such experiments the unfed mosquitoes must be separated from 

 the engorged ones. For removing Hving mosquitoes from a cage, 

 a device (Fig. 22) will be found very serviceable, and can be easily 

 made in the following way : Cover the end of a thick- walled rubber 

 tube with a piece of bobinet and push it two or three centimeters 

 into a glass tube, in which it should fit closely. The rubber tube 

 should have a lumen six or eight millimeters in diameter ; the 

 glass tube may be made by cutting off the closed end of a long 

 narrow test-tube. The rubber tube is held firmly in place by a 

 strip of adhesive tape wrapped around the junction of the two 

 tubes. In using the device, the end of the rubber tube is placed 

 in the mouth of the operator and one or several mosquitoes sucked 

 into the glass tube, which may then be closed with a cotton plug. 



Fig. 22. — Device for removing living mosquitoes from a cage. Shown in 

 longitudinal section. 



The insects are conveniently examined in the glass tube, under a 

 magnifier if desired, and subsequently blown into a new receptacle. 



One must be careful not to handle freshly engorged mosquitoes 

 too roughly, so it is usually best to leave them in the cage and 

 withdraw those which have not fed. It is easy to distinguish fully 

 engorged mosquitoes while in the glass cages. 



After the mosquitoes have fed on a carrier the cages are placed 

 on a shelf and tilted slightly on a piece of wood or some small 

 object to allow a free circulation of air in the cage. To insure 

 constant moisture, a piece of damp cotton is kept on top of the 

 cage. In a very dry climate it may be advisable to place plates of 

 water or moist cloths in the cabinet where the cages are kept. A 

 cupboard or meat-safe with screened doors makes a suitable re- 

 ceptacle for storing cages. It should be made ant-proof, else the 

 entire collection of mosquitoes may disappear overnight. 



Mosquitoes will live for five or six days after a blood meal with- 

 out any new food. If the infected mosquitoes must be kept for a 



