42 ROCHESTER ACADEMY OF SCIENCE. [March 10,. 
water as one or the other of these. This has resulted in the condemning 
of the waters of mountain streams by chemists who ventured positive 
opinions as to sanitary value on the evidence of chemical analysis alone. 
The use of the biological method, by exhibiting clearly the character of 
the organic contamination, will, therefore, lead to a more accurate 
knowledge of potable waters than can be gained by chemical analysis. 
Moreover as we gain more knowledge of the real sanitary signifi- 
cance of the various forms of plant and animal life, the daily or weekly 
fluctations in quality of a public water supply can be quickly obtained 
by the use of this method of biological analysis, and it is probable that 
in the'very near future all public water supplies in this and adjoining. 
states will be regularly subject to such examinations. Indeed the State 
Boards of Health of the States of Massachusetts and Connecticut have 
already begun a series of examinations, either weekly or monthly, in 
their respective states, and in the city of Boston I have been engaged a. 
‘portion of my time for the last eight months in supervising the details. 
of beginning an elaborate study of this kind as applied to the Boston 
supply. The Boston Water Board, with liberal foresight, have recog- 
nized the value of such new methods of examination, and have provided 
liberally for a practical test extending over a number of years. Daily 
records have been made for the last six months and show results of 
great value, though the full value of such work can hardly be determined’ 
in so short a time. At a recent meeting of the New England Water 
Works Association, Mr. F. F. Forbes, Superintendent of the Brookline, 
Massachusetts, Water Works, has given an interesting account of some 
similar studies which he made during the last season, with his results, 
and I will refer those interested to the Journal of that Association for 
further detail of such work. 
The following table shows the comparative value of the open cell 
with mixed sand and organisms, and the covered cell with sand and 
organisms separated. The results are in number of organisms per 
c. c.,and represent only the plant forms present in the given samples. 
(1) (2) 
NAME OF ORGANISMS. | Open cell | Closed cell Open cell Closed cell 
with sand, |without sand.|| with sand. |without sand. 
EStemonella se |) Wa eo 14 Ol ait 7 23 
Ralbellanrat. = wre ho ra baguk: II 21 4 15 
Crelotela yet ss | ien lies tes I I fo) 2 
AMADACT ay = | toler asa! 2 16 7 ne 
@Clathnocystiss ) kad a) all 4 era I 8 
Ccelosphacnium,) 5) | 5 12 5 3 
Nostoc, fo) 2 I I 
Melosira, je a eee 2 20 | I I 
Totals, SR at ates | Ba es0) 08 26 66 
