532 



Dr. P. F. Frankland. 



[June 10, 



further seen that when allowed to stand at a temperature of 20° C, 

 the multiplication which takes place in the course of a few days is 

 generally very considerable indeed, whilst at the temperature of the 

 incubator (35° C.) the multiplication, even in the course of a single 

 night, is enormous. On the other hand, when the storage is con- 

 tinued for a sufficient length of time, the number of micro-organisms 

 diminishes, and may become reduced below that which was present at 

 the outset. It would appear, however, that the micro-organisms in 

 these filtered waters become multiplied at 20° C. with far greater 

 rapidity than those in the unfiltered waters, which, as already pointed 

 out, have rather a tendency to become diminished, unless raised to 

 the temperature of the incubator. 



It now became a matter of interest to compare with the above the 

 power of multiplication which is possessed by the micro-organisms 

 found in deep well-waters. Similar experiments were, therefore, made 

 with the waters obtained from one of the wells in the chalk at Dept- 

 ford, belonging to the Kent Company. 



Number of Colonies obtained from 1 c.c. 



Description. 



Jan. 27/86. 



Day after 

 collection. 



Jan. 30/86. 

 Standing 

 3 days in 

 refrigerator, 

 temp, several 

 degrees above 

 0°. 



Jan. 30/86. 



Standing 

 3 days, at 

 20° C. (dark). 



Feb. 12/86. 



Standing 

 16 days at 

 20° C. (dark). 



Kent well . . . 



96 



163 



178,379 



51,843 



On comparing these results with those previously referred to, it will 

 be seen that whilst these organisms in the deep well-water have but 

 little tendency to multiply in the cold, the multiplication at 20° C. is 

 far in excess of anything observed in the case of the river- waters. 



Experiments were also made to ascertain the influence of the tem- 

 perature of the incubator upon the organisms in these well-waters. 



Number of Colonies obtained from 1 c.c. 



Description. 



Feb. 23/86. 

 Day of collection. 



Feb. 24/86. 



Standing through, 

 frosty night. 



Feb. 24/86. 

 Standing 1 night 

 in incubator, 

 36—39° C. 





5 



18 



743 





