198 Air and Water Poisoning 



by changes of organs and structure wliicli at length amount 

 to specific or even generic differences ; .... to bring 

 into being new races, whenever the earth, in its progress 

 from its primaeval to its present state, was prepared to 

 receive them. On either supposition, the correspondence 

 between the world and its inhabitants, at any given period, 

 is the result of adaptation." 



And the observation is of equal weight when applied 

 to our aquatic microcosm. 



Now, the organisms found by me in the Yan Yean water 

 on the occasion noted, and on others when I have subjected 

 it to microscopic analysis, were uniformly those which prefer 

 sweet pure water, and most, if not all, of them were sucli 

 as would disappear with greater or less rapidity on the con- 

 tamination of the water by decomposing animal matters or 

 refuse ; by such matters, I mean, as contain nitrogen, especi- 

 ally in albuminoid compounds, or sulphur, either unoxidised 

 or in a low state of oxidation. The other examinations 

 recorded above show that these same organisms did actually 

 die out of this same water on the addition of very small 

 quantities of such noxious matter. Consider, for example, 

 the case of the Lying-in Hospital (Case III.}, when the Yan 

 Yean was running through it, full bore, by day and night ; 

 so that the contents of the cesspit itself were nearly inodor- 

 ous in the bulk, and only became offensive after having 

 been bottled for some weeks, then of course they were bad 

 enough, simply because the matters which had not reached 

 the putrefactive stage when the sample was taken attained 

 it in the bottles without further dilution or change of liquid. 

 To me this part of the investigation was of extreme interest, 

 and you may judge from the number of species .determined 

 then, I spared no pains to make the evidence complete. 



I shall now be asked how I build on these observations a 

 diagnosis on the subject of the alleged contamination of the 

 Yan Yean. 



I have conceded to Mr. Johnson that a drowned bullock 

 or two would not produce any very marked effect, and might 

 escape notice altogether unless an analyst suspected it, and 

 laid himself out accordingly. I have pronounced that up. to 

 a recent period no such contamination was detectable in the 

 water, even by specially devised means ; nay, farther, that 

 the microscopic evidences are almost incompatible with its 

 existence ; and yet I now take part with those gentlemen 

 who have announced that the Whittlesea drainage falls- 



