in Melbourne. 191 



Lying-in Hospital, where a large body of pure water is being 

 constantly passed through, while in Dr. Tracy's, where the 

 flow was slower and the filter is in better order, scarcely any 

 were seen. In their place arises a new growth of fnngi, 

 anguillulse, and numerous species of the kolpod and allied 

 groups, all of which specially afiect decomposing and offen- 

 sive solutions. Rotifers were found, though in decreasing 

 number, in most of the liquids ; but this is explained by the 

 wonderful tenacity of life which characterizes these singular 

 animals. The changes here briefly described, and the effect 

 of natural selection were observed. The extent of dilution 

 in each case is well shown by the residues which are quanti- 

 tatively stated, and the several sets of data evolved in the 

 course of the investigations form a beautiful chain of con- 

 ditions, from which the history of the samples might almost 

 have been predicated, even without any previous information. 



After having thus minutely discussed the question of the 

 filters, I may speak more concisely of the liquid taken from 

 the several street gutters, to which most of the preceding 

 observations will apply. It is simply sewage, differing only 

 in age from that which flows in London sewers. Our sewer 

 is on the roadway instead of under it, and its contents are 

 carried oflT more rapidly. Moreover the gases it evolves, 

 instead of being confined in covered drains, and smelt only 

 through occasional gratings, are here diffused in the atmo- 

 sphere, to be breathed by the residents and passers by, and 

 only observed when they are more than usually noisome, 

 as in Bourke and Swanston-streets at night. Then it is a 

 ready-made pestilence. Fortunately, however, it is not long 

 stagnant in the main thoroughfare, and the stench is a 

 warning to get out of its way. The smell is only a slight 

 part of the evil, but it is an intimation that the material of 

 typhus lurks behind it, A stink, as I have long sicce 

 declared, is Nature^s ononitor, that something noxious 

 requires removal, and this is the view now generally held 

 by those who are regarded as authorities. 



The arrangement of the water-plugs, which admits of 

 water entering the mains from the street-gutters whenever 

 the pressure is removed, has before attracted attention. 

 This was of course always an evil, but the magnitude of it 

 was not known until now. The practice of flushing cess- 

 pits into the street is a recent one, and has of late become a 

 system. To the amount of filth thus deliberately discharged 

 into the public thoroughfares must be added a large and 



