PART IV. CARRIAGE BY H0USE-FLIES 147 



(2) Tetramitus mesnili free and encysted failed to infect a rat, 

 a mouse and a kitten. 



(3) A kitten and a mouse failed to become infected with the 

 human coccidium (Isospora). 



(4) Lizards (Agama sp.?) harbour tetramitus and an amoeba. 

 The latter resembles E. coli, both in the free condition and the 

 production of an eight-nuclear cyst. 



(5) House-flies readily take up free and encysted forms of 

 protozoa in faeces and can pass them from the gut as early as five 

 minutes and as late as twenty hours after feeding. 



(6) Wild flies captured in Alexandria often deposit in their 

 droppings cysts of protozoa and eggs of worms which they have 

 evidently taken up from human dejecta on which they have fed. 



(7) A series of weighing experiments show that a single house- 

 fly will take up one milligram of faeces in half an hour. 



(8) Cysts of E. histolytica will survive in water but are killed 

 instantaneously by drying. The cysts ai?e killed at once by 1 in 20 

 cresol solution. 



