190 TROPICAL MEDICINE AND HYGIENE 



The practice of some municipalities in allowing the 

 pails from the public latrines to be taken away by private 

 individuals, without exercising supervision to ensure that 

 this material is not used, even in part, fresh, is not to be 

 commended. Small gardeners (Chinese) usually have a 

 single cesspit and the contents of the latrine pails are 

 emptied into this, and the mixture of recent and old 

 deposits is then used as manure, and the eggs and 

 embryos distributed over the growing vegetables. The 

 moderately resistant eggs, those of flukes, often survive 

 this treatment. 



Poudrette, the product of the desiccation and con- 

 version into powder of the excrement mixed with ashes, 

 contains neither larvae nor ankylostome eggs, as these are 

 destroyed in this process. Even the crude method of 

 air-drying on a brick or cement floor and covering with 

 ash is effective to that extent. The method is only suited 

 for dry tropical climates. 



The expensive and wasteful method of the destruc- 

 tion of excrement by incineration naturally destroys all 

 eggs and larvae. It is only suitable in dry climates and 

 where there is abundant inflammable material to burn 

 with it. 



Addition of disinfectants in sufficient amount to destroy 

 eggs is difficult, and the faeces so treated are injurious 

 to land. 



Deposition in the sea or in salt water effectually 

 destroys eggs and larvae. In deep fresh water the method 

 is dangerous on account of pathogenic organisms often 

 contained in the faeces. The eggs and larvae in most 

 instances will fall to the bottom, and being embedded in 

 the mud are not so effective and are not likely to infect 

 man. 



The measures to be adopted must be those best suited 

 to the local conditions. Amongst other things, the size 

 of the settlement, the conservancy system in use, and the 

 land available and its nature, have to be considered. 



Cesspits are only permissible where surface wells are 



