210 Dr. A. Carpenter on 



pneumonia. (Some cases of these diseases did exist on Duppas 

 Hill about that time). It was while making these investigations 

 that I discovered a defect in my own left eye, which led me to 

 give up microscopical research, and which has smce disabled me 

 from assisting at the Society's microscopic demonstrations. 



Since that time I have been educating myself by the microscopic 

 studies of others in the same direction. It has been clearly proved 

 by experiment that actual putrefaction is generally destructive of 

 the life of disease germs, so that the only result which need 

 follow the inhalation of the offensive odours from sewers is the 

 necessity of calling the attention of the local authorities to the 

 fact that the sewer is a sewer of deposit, and before the stink 

 escaped might have been a source of danger to those passing by 

 that locality ? We may depend upon it that it is not the sewers 

 which stink that are the most dangerous, though before putrefac- 

 tion was complete, it was possible that there might have been 

 disease germs escaping from that particular opening,- though I 

 shall show presently that they need not excite serious alarm. 

 Let us go back to 



The Habitat of the Germ. 



]\Iany attempts have been made by various observers to catch 

 the organism. So difficult is this, that Prof. Nageli, of Munich, 

 endeavoured to show by a series of experiments which he carried 

 on for some years, that they are not given off by moist surfaces; 

 and Prof. Frankland said, in 1877, that nothing particulate was 

 given off from running sewage ; but as he has also shown us 

 since then that the bursting of bubbles disseminated particles 

 of lithia in solution, it is evident that whenever bubbles burst, 

 any particulate matter in the substance of the bubble might be 

 disseminated as well as the lithia. Some experiments have been 

 made by Mr. J. S. Haldane, in the Westminster Palace sewer, 

 which go to prove that micro-organisms were few whenever 

 there was a regular current of air ; that with little or no draught 

 there was an increase of carbonic acid, and with that an increase 

 of micro-organism, but they were moulds rather than bacteria. 

 But another very curious thing was found to exist — viz., that 

 when the ventilation within the sewer was much improved, so 

 so that COg was materially diminished, there was a considerable 

 increase in the number of bacterial organisms, as if a diminution 

 of oxidation allowed of the increase of germs. 



Mr. Haldane examined the air in the Bristol sewers, which 

 are not ventilated. He found that in those sewers the moulds 

 exceeded the bacteria, while in the air of the streets the bacteria 

 exceeded the moulds. 



Hesse has shown us that, although the spores of the moulds 

 are much larger than the bacteria, they remain suspended in 



