146 HUMAN INTESTINAL PROTOZOA IN THE NEAR EAST 



(8) The direct passage of practically unaltered material through 

 the gut of the fly would seem to be of more importance in the 

 distribution of disease generally than the regurgitation of such 

 material through the proboscis or its adherence to the legs or bodies 

 of the flies. 



(9) These observations all tend to emphasize the importance 

 of the well-known sanitary measures directed against the fly, its 

 destruction by traps and other means, the removal of its breeding 

 places, the protection of food, kitchens and dining rooms and 

 latrines from its inroads, and the removal of the dwellings of 

 natives as far as possible from those of the Europeans. 



(3) Resistance of Cysts of E. histolytica and other Intestinal 



Protozoa. 



In our former publications we have described our experiments on 

 the action of various reagents on cysts of E. histolytica. By way of 

 making the present report complete, we will enumerate the chief 

 conclusions here. We have explained that the eosin test as applied 

 by Kuenen and Swellengrebel seems to be reliable. Cysts which 

 stain with eosin are dead and those which resist the stain are alive, 

 This was the test we applied in determining the viability of cysts. 



(1) Cysts of E. histolytica will survive for over a month in 

 water provided there is great dilution of the faeces. 



(2) Cysts of E. histolytica will not withstand drying but are 

 killed instantaneously. The Thompsons have shown that the free- 

 living Amoeba Umax produces a cyst which will withstand complete 

 and prolonged desiccation under a tropical sun. 



(3) Cysts of E. histolytica are killed at once if faeces containing 

 them are mixed with an equal quantity of 1 in 10 cresol solution. 

 Free chlorine in water to a strength of 1 in 10,000 has no effect on 

 the cysts even after several hours' exposure. 



(4) Cysts of other intestinal protozoa behave in a similar 

 manner. 



The inference is that the intestinal protozoa will spread from 

 man to man only if the encysted stages remain moist, and this 

 condition is fulfilled in fly and water carriage. 



Summary of Matter discussed in Part IV. 



(1) Attempts were made to infect rats, mice and kittens with 

 E. histolytica, both in faeces and liver abscess pus. Two kittens 

 alone became infected. 



