310 BACTERIOLOGICAL AND ENZYME CHEMISTEY 



Group I. Ferments neither saccharose nor dulcite ; 



Group II. Ferments dulcite but not saccharose ; 



Group III. Ferments dulcite and saccharose ; 



Group IV. Ferments saccharose but not dulcite. 



To these Major Clemesha added sundry other fermentative 

 tests, whereby he was able to some extent to classify numerous 

 varieties of coli-hke organisms present, all of which are 

 capable of fermenting lactose. He found that certain of 

 these were characteristic of water which was obviously 

 recently polluted ; others, on the other hand, alone survived 

 when the water had been exposed to the sun for some time, 

 or was drawn from a well after long drought, etc. 



As nearly all the chief water supphes in tropical coun- 

 tries are, so to speak, of natural origin, that is, from wells, 

 rivers or lakes, and are subject to occasional pollution, and, 

 therefore, according to English standards would be classi- 

 fied as dangerous, it is obviously of importance to be able 

 to differentiate between the residue of pollution and the 

 presence of deleterious matter of recent introduction. While, 

 no doubt, further research and many more data are requisite 

 before it is possible, under all circumstances, to distinguish 

 between harmless and potentially dangerous supphes by the 

 characteristics of the organisms present, or by the chemical 

 reactions which they produce under given conditions, Major 

 Clemesha's researches are a very interesting apphcation of 

 bacteriological chemistry to the classification of water supplies. 



The Biological Purification of Trade Effluents.— 



Numerous effluents from manufacturing processes are highly 

 charged with organic matter, and are capable of bacteriological 

 purification by methods analogous to those used in the 

 purification of sewage ; such effluents are, e.g., those from 

 breweries and distilleries, from tanneries and hide-dressing 

 works, from beetroot sagar factories, starch works, wool- 

 scouring works, bone manure and glue factories. 



