1893.] MICROSCOPICAL JOURNAL. 129 



water drawn from the mains in different part of the city, (2) 

 freqnent examinations of the water of the two reservoirs of the 

 Rochester system, and (3) a stndv of samples taken from dif- 

 ferent parts of Hemlock lake as well as from the influent streams 

 and various parts ot the tributarv drainage area of the same.* 

 Incidentally, for purposes of comparison, studies were also 

 made of many of the streams and other bodies of water in the 

 vicinity of Rochester, as, for instance, the Genesee river. Lake 

 Ontario, Irondequoit bay, etc. 



The complete details of these various studies are too extensive 

 to be given at length, and we may merely refer to some of the 

 results at Hemlock lake, where plant forms have been identified 

 as follows : 



Chlorophvcete, 20; Cyanophyceae, 15; Desmidiae, 14, and 

 DiatomaceiT2. 41, making a total of plant forms of 90. The max- 

 imum quantities of some of these minute plants per 100 cubic 

 centimetres are, Protococcus, 2,000; Anabaena, 20,000; CceIos- 

 phcerium, 34,000; Asterionella, 40,000; Cyclotella, 60,000; 

 Fragillaria, 25,000; Stephanodiscus, 60,000. The total number 

 of animal forms is 93, of which 3 are classed as Spongidte ; 10 as 

 Rhizopoda : 39 as Infusoria ; 2 as Hvdroida ; 14 as Rotifera ; 3 

 as Polyzoa ; 31 as Entomostraca ; i as Malacostraca, and 10 as in- 

 sect larvte. As to maximum quantities of animal forms observed, 

 we find among infusoria. Dinobryon, 12,000; Glenodinium, 35,- 

 000, and Vorticella, 9.600. 



The quantities of minute life present in Hemlock lake, while 

 apparently large, are in reality quite small, as will be readily 

 appreciated by reference to a statement of the number present in 

 Ludlow reservoir, Springfield, Massachusetts, where the following 

 maximum quantities per 100 cubic centimetres have been observed ; 

 Of the diatoms, Asterionella and Melosira, 405,600 in April, 1890 ; 

 Coelosphgerium, 157,600 in August, 1889; Chlorococcus, 323,400 

 in October, 1889; of animal forms the infusorian Dinobryon 

 showed 364,400 per 100 cubic centimetres in Februarv, 1890.! 

 But even the large quantities of minute life found at Springfield 

 are dwarfed into comparative insignificance bv the results of a 

 series of examinations of the water supply of Newport, R. I., 

 as given by Dr. Drown in a recent report, from which it appears 

 that on August 31, 1S91, there were present in Easton's pond, 

 one of the sources of supply for Newport, the large number of 

 grass-green algae (Chlorophyceae) of 677,750 per 100 cubic centi- 



* Some of the results of these studies may be found in : 



1. On the IMicro-Organisms in Hemlock Lake Water. Proc. Micr. Sec. Roch. Acad. Sci. 

 1888. By Geo. W. K after. 



2. On Volvox globator as the Cause of the Fishy Taste and Odor of the Hemlock Lake 

 Water in 1888. An. kept. Ex. Bd. of the City of Rochester for the year end. April i, i88g. A 

 Rept. by M. L. Mallory. Geo. W. Rafter, and J. Edw. Line. 



3. Report on an Endemic of I'yphoid Fever at the Village of Springwater, N. Y., in Oct. 

 and Nov., 1889. In An. Repu of Ex. Bd. of the City of Roch. for vr. end. Apr. i, i8go. By 

 Geo. \V. Rafter and M. L. Mallory. 



4. On the Fresh- Water Algse and their Relation to the Purity of Puulic Water Supplies. 

 Proc. Am. Soc. C. E., Dec, 1889. By Geo. W. Rafter. 



t Derived from tabulations in the 22d An. Rept. of the Mass. St. Bd. Health. 



