232 MICRO-ORGANISMS IN WATER 



Whether the number introduced was large or small 

 the phenomenon of multiplication was observed, and in 

 the case of those samples kept at + 1 C. a subsequent 

 decline took place, whilst the higher temperature 

 appeared to favour very markedly the growth of these 

 particular water bacteria, and during the time over 

 which the observations extended no diminution in the 

 numbers was apparent. When introduced into sterilised 

 distilled water (which is water as chemically pure as 

 it is possible to obtain, in which the organic matter is 

 reduced to the merest trace) extensive multiplication 

 also took place. (The temperature at which these 

 samples were kept is not given.) 



Again, in order to dispose of any lurking suspicion 

 that this enormous multiplication in distilled water 

 might be due either to a trace of organic matter intro- 

 duced along with the bacteria, or to the breaking up 

 into their constituent individuals of zoogloea-masses of 

 the bacteria inoculated, Bolton made the following con- 

 clusive test. A minute trace of a pure culture of the 

 Micrococcus aquatilis (similar experiments were made 

 with similar results also with the Bacillus erythrosporus) 

 was introduced into some sterilised distilled water ; 

 after three days extensive multiplication was found to 

 have taken place, and a minute trace of this water was 

 then inoculated into a fresh quantity of sterilised distilled 

 water ; after three days extensive multiplication was 

 found to have taken place in this also ; from the latter, 

 again, a minute trace was taken and inoculated into a 

 fresh quantity of distilled water, and so on up to seven 

 times, and in each case the most abundant multiplica- 

 tion was found to occur. 



Hence, in the case of these two water bacteria 

 capacity for multiplication was shown even in the ab- 

 sence of almost every particle of organic matter. 



