1892.] MICROSCOPICAL JOURNAL. 55 



Biological Examination of Potable Water. 



By GEO. W. RAFTER, 



ROCHESTER, N. Y. 



[From Proceedings of tlie Rochester Academy of Science.] 



The biological examination of water requires the determination of 

 all the minute life occuring in various classes of water, and is divided 

 into tw^o distinct investigations, the microscopical and the bacterial. 

 The microscopical examination includes the determination of all those 

 forms of life w^hich are easily studied in all their phases by use of the 

 microscope. These forms include among plants, algte, larger fungi, 

 etc., and among animals, sponges, infusoria, rotifers, the smaller 

 Crustacea, and others. 



COMPLETE APPARATUS FOR BIOLOGICAL EXAMINATION OF WATER. 



The bacterial examination requires cultures as an integral part of 

 the process, and only incidentally makes use of the microscope, inasmuch 

 as examinations and partial identifications may be made from plate and 

 tube cultures without the use of the microscope at all. 



The methods of making bacterial examinations have been fairly 

 worked out for several years, but until recently no definite method of 

 making the accurate determination of the number of the so-called 

 microscopic forms has been known. 



The present paper includes the microscopical examination only, 

 and the methods here indicated have no reference to the bacteria. 



Something over three years ago the Microscopical Section of this 

 Academy- began a systematic study of the forms of minute life present 

 in the Hemlock Lake water supply of this city. The method of 



