62 Dr. Edward Franldand [Feb. 21, 



organism has ever been discovered, even in the imfiltered water as it 

 enters the intakes of the various companies, although these organisms 

 have been carefully sought for. It is sometimes even said that the 

 non-pathogenic organisms found in water may be beneficial to man, 

 but this idea is not borne out by their entire absence from the food 

 which nature provides for young animals. Milk is absolutely sterile 

 in its normal condition. 



As it is at present impracticable to obtain water, uniformly at 

 least, free from microbes, it is desirable to adopt some standard of 

 bacterial purity ; and 100 microbes per c.c. has been fixed upon by 



MICROBES IN RAW AND FILTERED THAMES 

 WATER 1894. 



fEBRUARY MARCH APRIL 



JUNE JULY AUGUST SEPTeMBER 



october november december m£aw 



Fig. 12. 



Dr. Koch and mj'pclf as the maximum number allowable in potable 

 water. This standard is very rarely infringed by the London water 

 companies ; whilst I have every reason to hope that, in the near 

 future, now that special attention is directed to bacterial filtration, it 

 will not be approached within 50 per cent. 



This hope is based, not only upon my own observations, but also 

 upon the exhaustive and exceedingly important investigations carried 

 out at the Lawrence Experiment IStation by the State Board of Health 

 of Massachusetts, under the direction of Mr. George W. Fuller, the 

 official biologist to the Board. More than six years have already 

 been spent in the prosecution of these American experiments, and 

 many thousands of samples of water have been submitted to bacterial 

 cultivation. 



The Massachusetts experimental filters were worked at rates up to 



