1886.] 



On the Multiplication of Micro-organisms, 



537 



Experiments with the Bacillus pyocyaneus. 



A large number of experiments were made upon the vitality of 

 this organism when introduced into various kinds of water. The 

 results of these experiments show that on introducing this organism 

 into purer water, such as distilled water, deep well-water, or filtered 

 Thames water, in the first instance a greater or less reduction in the 

 number of organisms capable of development often takes place, but 

 sooner or later a considerable increase in their numbers generally 

 follows, and only in very exceptional cases was the complete destruc- 

 tion of their vitality observed. On the other hand, when the same 

 organism is introduced into sewage a rapid and large multiplication 

 was observed in every case. From a number of bottles of distilled 

 water which were inoculated with the Bacillus pyocyaneus in the 

 manner described above, the following number of colonies were 

 obtained. 



Bacillus pyocyaneus in Distilled Water. 

 Number of Colonies obtained from 1 c.c. 





Day of 

 prepara- 

 tion. 



2nd Day. 



3rd Day. 



7th Day. 



20th Day. 



53rd Day. 



No. 1 .. 



6,100 



203 







276 



100,000 



„ 2 .. 



6,800 



368 







13,400 



69,000 





(Incub.) 







(Incub.) 



„ 3 .. 



15,400 



1,557 







69,600 



249,000 





(Incub.) 







(Incub.) 



» 4 .. 



3,200 





6,200 



96,000 











(Incub.) 



(Incub.) 







„ 5 .. 



3,200 









19 







„ 6 .. 



114,000 









38,000 





* 7 .. 



165,000 





















(Incub.) 







„ 8 .. 



165,000 















Note. — " Incub. " means that the sample above was kept in the incubator at 35° C. 



Bacillus pyocyaneus in Filtered Thames Water. 

 Number of Colonies obtained from 1 c.c. 



Day of preparation. 3rd Day. 



No. 1 3,900 Innumerable. 



No. 2 3,900 Innumerable (incub.). 



