PLANKTON IN THE WATER SUPPLY 



By Flobence E. Meier 



Associate Plant Physiologist, Division of Radiation and Organisms, 

 Smithsonian Institution 



[With 11 plates] 

 INTRODUCTION 



"It is good to keep water in copper vessels, to expose to sunlight and 

 to filter through charcoal," are the words of an ancient Sanskrit 

 author written in 800 B. C, more than 27 centuries ago. Water has 

 been a necessity since the beginning of life, and the problem of ob- 

 taining pure water free from disease germs has increased in magni- 

 tude with the complex growth of civilization and the crowding of 

 people into towns and cities. The importance of a good water supply 

 has long been recognized, as testified by Caesar's aqueducts, but the 

 importance of a standard of purity in drinking water is more recently 

 indicated by the statistics showing the decrease in death rates of 

 cities, a decrease due to the elimination of water-borne disease germs 

 from city water supplies. 



Nature is abundant in her gift of water, but since water is the home 

 of countless living organisms, many of them harmless, others directly 

 injurious to man, it is essential to determine means for their elimina- 

 tion in order to insure a satisfactory domestic water supply. 



In medieval times the smaller populations caused comparatively 

 little contamination of the water. When epidemics of dysenteiy and 

 typhoid fever did occur, owing to pollution of the water, they were 

 accepted more or less as a matter of course. Our ancestors would be 

 amazed at the science of modern waterworks, involving engineering, 

 bacteriology, biology, and chemistry, which has been developed to 

 ascertain water purity. Very often an expensive installation that has 

 been constructed for the storage and delivery of water serves its pur- 

 pose for a time, but then the quality of the water deteriorates or the 

 supply dwindles or even abruptly ceases. The installation set up by 

 man, instead of preventing, may propagate the microorganisms in the 

 water that cause spoiling of the water or interference with its flow. 



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