318 THE AMERICAN MONTHLY [Oct. 



It has nothing whatsoever to do with artificial causes 

 like drainage, sewage or contamination. It is due to 

 purely natural causes,, the first being the microscopical 

 chemical constituents of the water, and the second, and 

 even more important, being the physical conditions in 

 which the water is placed after entering the reservoirs. 

 The important questions to consider are : 



I. What is the Asterionella, and what is peculiar 

 about it ? 



II. What is there in the composition of the Brooklyn 

 water, or the mode of handling and storing it, that has 

 fitted it especially for the development of the Asterio- 

 nella ? 



III. How can growth of this organism be prevented ? 



I. Asterionella derives its name from its form, being 

 a star-shaped organism usually 3- or 4-rayed. It is a 

 diatom, a bacillarian, usually called an alga, although 

 more properly called a protiston. The latter is distin- 

 guished from most other algse by being enclosed or hav- 

 ing a skeleton or envelope capsule of silica, or soluble 

 silica hydrate. This particular genus has the further 

 peculiarity of secreting a substance in the nature of an 

 oil which possesses a taste and odor so characteristic 

 that, for lack of a better name, is is called Asterionella 

 flavor. It is a combination of fishy, salty and oily tastes, 

 its odor resembling that of certain varieties of geranium. 



Although some of the samples of the reservoir water 

 contained as many as twenty million individuals to the 

 gallon, yet it would require many hundred gallons of the 

 water to get enough of the oily product which imparts 

 taste and odor, to work upon in the laboratory to accu- 

 rately determine its nature. In many of its properties 

 it resembles trimethylamine. 



In the month of August, when the trouble was at its 

 worst, the water had a white appearance and was filled 



