Plate XIX 



Fi. 



Fi-. 



Fig. 3- 



Fig. I. Glass cage in which infected flies were kept, consisting of a glass cylinder 

 9x3 inches, covered with gauze at one end and open at the other. (^ nat. size.) 



Fig. 2. Glass cage with apparatus, through which to extract flies, in place. The latter 

 consists of a board in which a round hole slightly larger than the diameter of the cage 

 had been cut and lined with cloth so as to grip the sides of the cage. On to the cloth 

 gauze was sewn to form a conical bag open at the free end. (^ nat. size.) 



Fig. 3. Gauze bag in which normal stock flies were kept. Note the sleeve at the side 

 through which the flies were extracted. (^ nat. size.) 



(From Graham-Smith, Report to Local Government Board, No. 40, 1910.) 



