1552 Journal of Applied Microscopy 



great chemical purification of the material, but the results of such careful exper- 

 iments have seemed to indicate that ordinarily this treatment does not materially 

 reduce the bacteria, and it is very questionable whether it lessens the danger of 

 the sewage material distributing diseases. The author of the present article 

 points out that no satisfactory means has yet been employed for destroying the 

 bacteria in sewage sufficiently to reduce in any great measure its pathogenic 

 nature. It should be noted that the results obtained in the bacterial purification 

 of sewage are not always in harmony, and certainly in many of the sewage plants, 

 particularly in this country, there is a very remarkable reduction in bacteria, 

 which surely renders the sewage far less liable to distribute disease. In the filter 

 beds used in the vicinity of London, however, such a reduction is not very great, 

 and the author is of the opinion that entirely new methods must be adopted in 

 the treatment of sewage before we can be satisfied that the problem has been 

 mastered. His general conclusions are five, as follows : 



1. The lines of defense which protect us from invasion by sewage borne 

 disease germs are defective and uncertain. Consequently, it is ever necessary 

 to strengthen these deficiencies by all means in our power. 



2. The presence of disease germs in sewage and the possibility of their sur- 

 viving the various processes for sewage purification cannot be ignored. 



3. We are ignorant with regard to the fate of these germs before, during, and 

 after the processes of purification, and can only say that, so far as the evidence 

 hitherto acquired shows anything, it tends to prove that the disease germs are not 

 necessarily destroyed by the purification processes. 



4. It is imperative that investigations (similar to those described above) should 

 be continued, developed, and applied to the various systems of purification by 

 precipitation, by " bacteria beds," etc., and by land filtration and irrigation. 



5. Any effluent which has been so far purified that it is free from putrescible 

 matter and incapable of giving rise to offensive nuisance must still be regarded 

 as capable of giving rise to disease until it has been shown that the disease germs 

 have been eliminated from it. h. w. c. 



Weissenfeld. Uer Befund des Bakterium coli -pj^g ^^^j^qj. investigates the question 

 in Wasser und das Thierexpenment sind ° ^ 



keine brauchbaren Hilfsmittel fur die hy- as tO whether the presence of the com- 



gienische Beurteilung des Wassers. Zeit.f. j^^^ B. coll in water is an indication 

 Hyg. 34: 70, 1900. 



of the unhealthfulness of the water. It 

 has generally been assumed that the presence of this organism in quantity is an 

 indication of sewage contamination, and consequently an indication that the 

 water in question is unwholesome. The author uses modifications of Pariettii's 

 fluid, and having isolated his organisms injects them into guinea pigs. The 

 conclusions that he reaches in regard the B. coli from the waters which he 

 studied were, that the organisms isolated from the best waters were commonly 

 pathogenic for guinea pigs, whereas those isolated from the suspicious waters, 

 and waters of a clearly undesirable character, were less pathogenic, or indifferent 

 in their action upon guinea pigs. He therefore is of the conclusion that the dis- 

 covery of B. coli in water is not necessarily an indication of sewage contamina- 

 tion. H. w, c. 



