368 MEDICAL ENTOMOLOGY 



and in this way Mitzmain kept Stomoxys calcitrans alive for ninety- 

 four days. The tube used had a bore of 24 mm. and was plugged 

 with cotton wool. A piece of white filter paper, of suitable size and 

 kept moist, is placed in the tube ; both paper and tube should be 

 changed at least every two or three days. 



In feeding a large number of flies, kept in a bottle, on a monkey, 



Mitzmain used the following method : The monkey is strapped with 



its abdomen downwards to a table. The hair of the 



M8t u d . 8 ,. 0f * aP !!l ying tail is closely cropped, and is then tied to a stout 

 the flies to the J h 



Host wire by means of gauze and passed through the neck 



of the bottle containing the flies. The other end of 

 the wire is kept at a convenient distance from the mouth of the bottle in 

 order to facilitate the manipulation of the tail. It is most important 

 to immobilize the tail by fixing it to the wire, or the animal 

 switches it against the sides of the bottle and crushes large numbers 

 of the flies. Single flies may be fed on the monkey by inverting 

 the tubes over the thighs; at least two flies can be fed at the same 

 time in this way. It is not necessary to screen the mouth of the 

 tube. When about to apply it, its base is directed toward the window 

 light, the plug withdrawn and the filter paper pulled out with forceps ; 

 the tube is then inverted over the skin of the host. When the fly 

 is replete a few taps on the glass will cause it to fly up ; the tube 

 is withdrawn, the filter paper replaced and the mouth of the tube 

 plugged with cotton wool. The flies should be kept in the dark at 

 a temperature of 20 to 26 C. 



Flies can be fed on a guinea pig or other small animal by strap- 

 ping it to a brass frame, which is passed into the jar containing the 

 flies. The jar is held horizontally with the bottom towards the light. 

 As soon as the flies have fed they collect at the bottom of the jar, 

 being attracted by the light, and this is taken advantage of in order 

 to remove and introduce them. When it is required to change the 

 animal a few drops of chloroform or ether on the cloth cover facili- 

 tate its removal without killing the flies. It is best to shave the 

 back of the animal. 



Single flies in test tubes may be fed on small animals in the same way 

 as on monkeys. 



Large numbers of flies may be fed on the shaved abdomen of a calf or 

 horse by strapping it down to a table ; the skin of the animal should be 

 moistened, as this attracts the flies. In the case of exact experiments 

 with trypanosome-infected flies the skin should never be shaved, as 



