324 Bacteria and Sewage. [March 9, 



as the bed " matures," is sufficient to show that the action is by no 

 means of a mechanical nature. It would be well, therefore, to speak 

 of it as a process of bacterial treatment, and thus to indicate that the 

 purifying agents are bacteria, which are acting under control, aud 

 are placed under conditions favourable to the development of their 

 full activity. 



It would be rash to say that the methods of bacterial treatment 

 have as yet reached their most effective state; but it is significant 

 that these methods have secured converts wherever they have received 

 careful and fair trial, and that those are their warmest advocates who 

 have had the widest experience of their working. It is even probable 

 that further improvements will be made in the means of treating 

 sewage bacterially ; but it is quite certain that the processes at pre- 

 sent in use are able to secure the economical and satisfactory purifi- 

 cation of ordinary town sewage. 



[F. G] 



