PATHOGENIC BACTERIA IN DIFFERENT WATERS 287 



vitality of bacteria, and have seen that the composition 

 of the water into which they are introduced is of car- 

 dinal importance, we have so far omitted from the diffi- 

 culties besetting the investigator perhaps the most 

 troublesome of all, viz. the individual characteristics 

 possessed by micro-organisms, and not only exhibited 

 by different varieties, but even by the different indi- 

 viduals in one and the same cultivation, rendering it 

 essential that in all experiments the previous history, 

 as far as possible, of the organisms under observation 

 should be recorded. 



In the following tabulated series of researches on 

 the behaviour of pathogenic bacteria in various waters 

 we have endeavoured to give in all cases as fully as 

 possible the essential details of the experiments as 

 described by the authors themselves, together with the 

 references to the original memoirs in which they are 

 recorded. The following is a list of the micro-organisms 

 subsequently dealt with : 



1. Bacillus typhosus-abdominalis 10. Bacillus of rabbit septicaemia 



(Typhoid Bacillus) 11. Bacillus of fowl cholera 



2. Spirillum cholerae asiaticae 12. Bacillus of swine plague 



3. Bacillus anthracis 13. Bacillus of glanders 



4. Bacillus tuberculosis 14. Bacillus of pneumonia 



5. Staphylococcus pyogenes-aureus 15. Bacillus of Finkler-Prior 



6. Streptococcus pyogenes 16. Bacillus pyocyanetis 



7. Streptococcus erysipelatis 17. Aspergillus flavescens 



8. Micrococcus tetragenus 18. Bacillus of tetanus 



9. Bacillus of mouse septicaemia 



The mode of procedure usually adopted by the 

 various investigators is to ascertain at different intervals 

 of time, generally by means of plate-cultures, whether 

 the organism is still present in the water in a vital con- 

 dition. By this means information is also obtained as 

 to the decrease or increase which has taken place in 

 the numbers present during residence in the water. 



