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BIOLOGICAL 



STUDY OF THE TAP WATEE 



IN THE SCHOOL OF PRACTICAL SCIENCE, TORONTO. 



BY GEO. A C H E S O N, M. A. 



Science Master in Toronto Collegiate Institute. 



The object of this paper is to give the results of investigations 

 into the biological nature of the suspended matter in the tap-water 

 of the School of Practical Science. No pretence is . made of being 

 exhaustive, for the work has only been carried on at intervals, and 

 observations for any definite length of time have not been continu- 

 ous. The results therefore are fragmentary, but may serve as a basis 

 for future and more extensive research. A thoroughly systematic 

 examination of the water should include not merely the determine 

 tion of the animal and vegetable species which are to be found in it,, 

 but the physiological influence which these organisms exert, and 

 their importance from a sanitary standpoint. This subject accord- 

 ingly may be dealt with from both a morphological and a physio- 

 logical point of view. It is with the first of these aspects only that 

 the present paper is concerned. In regard however to the physio- 

 logical and hygienic aspect it may be briefly observed, that the 

 purity of water does not depend merely on the quantity of organic 

 matters which it contains ; for, if these be living vegetable growths 

 containing chlorophyll, they have a beneficial influence on the water,. 

 by supplying oxygen to it and removing carbon dioxide, provided, of 

 course, that their presence in large quantities does not counterbalance 

 their salutary effects. On the other hand, there are oi'ganisms 

 which, even if present only in small numbers, exert a very prejudi- 

 cial influence, and which, if undoubtedly recognized as constantly 

 occurring, should mark a water as unfit for use. 



To obtain matter for examination two methods may be employed.. 

 One is to tie a muslin bag to the tap and allow the water to run in 

 a slow stream for a few hours ; then, taking off the bag, rinse it in 

 a small quantity of water, which, on being allowed to settle for a 



