WATER SUPPLY OF THE PHILIPPINE ISLANDS. 123 



shows a very low number of bacteria and therefore such a process would 

 greatly lessen the danger of bacterial infection for those who refuse to 

 sterilize the hydrant water by some means before using it. Some experi- 

 ments in sand filtration have been carried on in Manila, but these were 

 only in mechanical filtration and left out of account the biological prin- 

 ciple upon which all sand filtration should be based. The experiments 

 of Musgrave and Clegg show that amoeba? require some organism to be 

 in symbiosis with them, hence it is not difficult to believe that a reduction 

 in the number of amcebas would follow a diminution in the number of 

 symbiotic organisms which, in this case, would be the bacteria in the 

 water. It is a disputed point whether or not all amoebae are pathogenic. 

 If they are not, it would follow that by means of the reduction of the 

 number of bacteria we might eliminate the pathogenic ones and so by 

 the diminution of the total number of amcebse, escape those which are 

 pathogenic. Aside from this factor we know that natural immunity, or 

 the sterilizing action of a healthy stomach, is able to a certain extent to 

 protect individuals from intestinal bacterial infections. We know that 

 many people in these Islands consistently refuse to sterilize the drinking 

 water which they use, and a much larger number have their dishes washed 

 only in unsterilized tap water. 



Only a few years ago, the prevalence of amoebic dysentery among Euro- 

 peans was so great as seriously to reflect upon the Islands as a home for 

 the Caucasians. However, the experience then gained was followed by 

 the adoption of great precautions by this part of the population so far 

 as purity of food and water was concerned, but now many persons who 

 have had this experience have left, or have to a slight degree become 

 immune to the ordinary chances of infection and the remainder are 

 correspondingly careless. New arrivals are constantly appearing, and 

 with such changes in the population and with certain other factors which 

 we do not understand, we may probably have another epidemic at some 

 future time, but we can furnish an improvement in the future water 

 supply in the shape of a slow sand filtration plant. This would also 

 probably help in the continual fight against cholera in Manila. 



Few samples of waters bottled and for sale have been condemned and 

 these, with one exception, were cheap products sold from low-class shops ; 

 only one sample of a reputable brand of water was condemned for high 

 bacterial count, while no other of the same brand of water had even ten 

 bacteria to the cubic centimeter, hence we would conclude that reputable 

 brands of bottled water are safe. 



No flavoring extract was condemned and only a few samples of soda 

 water and lemonade, but the number of specimens examined was so small 

 that we should draw no conclusions therefrom. 



The specimens from artesian wells gave most satisfactory results, 

 as only 8.5 per cent of the wells were condemned. The high figure 15.8 



