1894. NOTES AND COMMENTS. 93 



abhorrence. His surprise will probably be no greater than his 

 satisfaction when he learns from the Reports on Sewer Air recently 

 presented to the London County Council by Mr. J. Parry Laws, that 

 this enemy is in many respects less black than has been painted. Mr. 

 Laws' experiments only confirm the results previously obtained 

 by others in this country and abroad, but they will appeal to the 

 Londoner with particular force, as having been carried out in some of 

 the oldest, and, in some instances, the worst of his own sewers. They 

 deal mainly with the number and character of the bacteria of sewer 

 air as compared with those of fresh air taken at the same time in the 

 vicinity, under normal and abnormal conditions. Normal sewage 

 contains enormous numbers of micro-organisms — from four to six 

 millions or more to the cubic centimetre — and it might have been 

 expected that air in prolonged contact with such decomposing and 

 fermenting sewage would have become highly charged with bacteria. 

 In most cases, however, Mr. Laws found, as others had found before 

 him, that fewer micro-organisms were present in sewer air than in 

 fresh air taken at the same time, and, which is more important, that 

 those present were related to and apparently derived from the outside 

 air, and not from the sewage. No effect on their number seemed to be 

 produced by moderate splashing, or, in an experimental sewer, by a 

 considerable increase in the velocity of the air current, or even by 

 drawing air through a sewer which had been kept empty for twelve 

 days. 



A mere knowledge of the number of bacteria present is of less 

 moment than an insight into their nature, and an attempt was made 

 in every case to determine the species present. Not only were no 

 pathogenic species found, if we except one or two feebly pathogenic 

 Staphylococci, which would not harm us if they could, but the bulk 

 of the species present were of a positively ornamental character, and 

 we read with pleasure that our sewers are inhabited by Sarcina 

 aurantiaca, Bacillus aureus, and Micrococcus candicans. If this be so, it 

 must be admitted that, whatever the injurious effects of sewer air may 

 be, we have no experimental evidence of the presence in it of specific 

 germs derived from the sewage. And in this connection may be 

 noted the well-known fact that sewer men are not more liable to 

 zymotic disease than other members of the community. The baffled 

 hygienist must hence take refuge in hypothetical poisons of a chemical 

 nature if he wishes to explain the deleterious effects of sewer air. 

 The evidence of such injurious action is so strong that it cannot be 

 ignored, and it may well be that the effect is a secondary one, and 

 produced by lowered powers of resistance to specific poisons derived 

 from other sources. 



Science and Literature. 

 Meanwhile we have strayed rather far from Professor Du Bois- 

 Reymond and his views on art. Let us hark back for a moment, for 



