Kirchner — Bacteriological Examination of River Water. 295 



that erroneous conclusions are drawn from isolated or separate 

 tests and insufficient data. We should have at hand chemical 

 analyses of the water so that we may have information as to 

 the mineral and organic constituents. We should have a 

 knowledge of the flora and fauna of the water, of the topog- 

 raphy and geology of the river-basin, and of certain 

 meteorological conditions. The location and influence of 

 cities, villages, factories, sewers and tributary streams; the 

 effect of river traffic ; the variations in the depth of the 

 water; the velocity of the stream, and the tendency to sedi- 

 mentation ; the degree of pollution and the distance of the 

 source of pollution ; the health statistics of the communities 

 along the river ; a knowledge of these and many other condi- 

 tions may be necessary before an intelligent interpretation of 

 bacteriological data of river water as affected by sewage may 

 be arrived at. 



When we consider the suffering, the loss of life, and the 

 cost which an epidemic entails upon a community, as well as 

 the harm done to its commercial interests, we are compelled 

 to recognize the importance of a wholesome water supply. It 

 is incumbent upon a community to look after the health 

 of its inhabitants, and it is important that the water supply 

 receive careful and proper attention. The question of the 

 pollution of streams and the consequent contamination of 

 the water supply by sewage from cities and towns has, 

 of late years, received national recognition, but the problems 

 involved in arriving at true conclusions are difficult, and 

 can be only satisfactorily solved by the most careful and 

 scientific inquiry. 



