PART IV. CARRIAGE BY HOUSE-FLIES 139 



(7) Nine flies were fed on faeces of case Hancock with a large 

 number of cysts of E. histolytica present. The flies were dissected 

 forty-two hours after feeding. In every case the gut was empty 

 and no cysts were discovered. 



(8) Eight flies were fed on faeces of case Badharn which con- 

 tained large numbers of cysts of Lamblia intestinalis. The flies 

 were dissected twenty-four hours after feeding with the following 

 results : (a) One fly had no faeces in the gut and no cysts were 

 found. (b) Two flies had very little faeces and no cysts were 

 found, (c) Five flies had a good amount of faeces in gut and 

 numerous lamblia cysts were present. With eosin some stained 

 and others did not. 



From the foregoing records of feeding experiments it is clear 

 that flies readily take up cysts when they feed on faeces, and that 

 these cysts remain in the gut so long as faeces remain there. The 

 flies, however, get rid of the faeces in twenty-four hours, after which 

 cysts can no longer be found. In the experiments recorded above 

 the flies were given no food after having fed on the faeces. It is 

 probable that the fasces would be more quickly got rid of if the flies 

 were feeding constantly as they do in nature. FuffGer, the cysts 

 do not degenerate to any extent ; at any rate, the length of time the 

 cysts would remain in the gut under natural conditions would not 

 be enough to bring about their degeneration. 



(b) Flies fed on Infected Faces and their Fcecal Droppings 

 examined later. (1) One fly was allowed to feed on faeces of 

 case Hancock with large infection of E. histolytica cysts. Half 

 an hour later six dried faecal deposits were taken up in eosin saline 

 solution. There were present a fair number of Jjysts of E. histolytica, 

 all of which were stained. A further number of droppings were 

 taken up two hours later with a similar result. 



(2) Four flies were allowed to feed as above. Two hours after 

 the faeces had been removed the flies were given fresh faeces on 

 which to feed. Soon after feeding some moist faecal droppings were 

 taken up in eosin saline. There were present fair numbers of cysts 

 of E. histolytica which did not stain with eosin. 



(3) Six flies were fed on faeces of case Hancock with large infec- 

 tion of cysts of E. histolytica. Sixteen hours after the removal of 

 the faeces the flies were given sugar and water on which to feed. 

 The droppings which were deposited soon after were taken up 

 while still moist in eosin saline solution. There were present fail- 

 numbers of cysts of E. histolytica which did not stain with eosin. 



(4) Six flies were fed on faeces of case Hancock with large 



