258 BACTERIOSCOPICAL EXAMIXATION OF ICE SUPPLIED IN SYDNEY, 



and thawing of the water mixed with bacteria, causes them to 

 perish in a comparatively short time. The ability possessed by 

 bacteria to resist great cold differs according to the species, and 

 is dependent on the conditions of life in which the organisms were 

 before being subjected to the experiments under consideration. 

 (As I have been unable to consult the Medical Record I do not 

 know whether any of the bacilli expeiimented upon Vjy Prudden 

 were in a spore-formation or not ; this, of course, has to be taken 

 into account when judging of the relative degree of the power of 

 resistance of microbes against excessive cold or otherwise.) 



Bordoni-Uffreduzzi (I.e.), in contradistinction to Prudden (who 

 employed artificial excessive cold\ found that the natural raw ice. 

 six months after its forination, exhibited nearly the same quantity 

 of bacterial germs as on the firf<t day. This result, which is con- 

 trary to Prudden's conclusion that the number of micro-organisms 

 in naturally frozen water diminishes in proportion to the duration 

 of freezing, is, he says, to be accounted for by the divergence of 

 the conditions under which the experiments were carried out in 

 either case. 



From a sanitary point of view a biological investigation of the 

 ice from the supply in Sydney, seemed to me to be not without 

 interest; so much the more as the consumption of ice in this City 

 and its suburbs, during the summer months, is by no means insig- 

 nificant. For instance, the weekly sale from the works of the 

 "New South Wales Fresh Food and Ice Company," is about 120 

 tons, of which almost all is used here. 



The investigations made by me were chiefly for the purpose of 

 ascertaining the quantity of bacterial life in the different ice 

 samples. I could not examine the water which was used each 

 time for the preparation of ice — as a matter of course we have here 

 only ai'tificially produced ice — but I could refer, to some extent, 

 to the analyses of pipe-water (from the tap in the Linnean Hall) 

 which I had made during 1886 and 1887, and also to a few 

 recently made examinations. This water comes from the same 

 source (Nepean Paver), as that supplied to the Sydney Ice-works 



