1886.] On the Multiplication of Micro-organisms. 531 



Number of Colonies obtained from ] c.c. 





Jan. 16/86. 



Jan. 20/86. 



Jan. 23/86. 



Feb. 12/86. 



Mar. 2/86. 





Day after 



Standing 



Standing 



Standing 



Standing 



Description. 



collection. 



5 days in 



7 days in 



27 days 



45 days 





temp, about 



dark at 



refrige- 



at 20° C. 



at 20° C. 





3 U. 



20° C. 



rator. 



in dark. 



in dark. 



Filtered River 













Waters. 















lov 



lost 



1 1 A Q*7 



ll,4o/ 







West Middlesex . . 



180 



lost 



2,063 



312 



76 





2,270 



5,285 



8,311 



1,323 





Grand Junction . . 



4,894 



15,950 



14,965 



3,757 







2,587 



6,980 



6,774 



2,749 







363 



lost 



750 



3,132 



43 





224 



lost 



3,39: 



947 



410 





1,525 



9,405 



6,813 



2,163 



176 



Experiments were also made in order to ascertain the extent of 

 multiplication taking place when samples of the filtered river- waters 

 are exposed for twenty- four hours respectively in frosty weather, and 

 in the incubator. The results obtained are comparable with those 

 already recorded for the crude river-waters which were similarly 

 exposed. 



Number of Colonies obtained from 1 c.c. 





Feb. 23/86. 



Feb. 24/86. 



Feb. 24/86. 



Description. 



Day of collection. 



Standing through 

 frosty night. 



Standing through 

 night in 

 incubator. 



Filtered River Waters. 











305 



305 



62,483 





80 



112 



3,580 





284 



360 



1,954 





208 



263 



22,842 





265 



314 



44,289 





74 



107 



8,892 





252 



633 



7,152 





210 



299 



21,599 



Thus the micro-organisms in the filtered river- waters, on standing 

 for twenty-four hours, even in cold weather, undergo a slight although 

 distinct multiplication, thus bearing out the observations made with 

 the same waters when kept in the refrigerator for a week. It is 



2 n 2 



