230 MICRO-OHGANISMS IN WATER 



Thus, whilst in the unboiled water the multiplication 

 was quite insignificant, in the boiled w^ater it was alto- 

 gether enormous. 



The above results, obtained with the unboiled city- 

 water, also illustrate the point, which we have before 

 referred to more than once, viz. that bacterial multi- 

 plication in surface waters may, in some cases, either 

 not take place at all, or only to a limited extent (see 

 pp. 219-224). 



Still more recently investigations have been made 

 by Percy Frankland^ on the power of multiplication 

 possessed by the bacteria present in Loch Katrine water 

 as supplied to Glasgow. This is, as is well known, a 

 peaty, moorland water, the organic constituents of which 

 are nearly all of vegetable origin, almost wholly destitute 

 of mineral matters, and excessively soft, differing entirely, 

 therefore, in character from the waters described above. 

 Samples were placed in a refrigator, the temperature of 

 which was 9° C, also in an incubator maintained at 

 19° C The following table exhibits the rate of multi- 

 plication exhibited by these bacteria at the high and low 

 temperature respectively : — 



Loch Katrine Water at 19° C. 



Date of Number of micro- 



examination oVganisms per c.c. 



On July 6, 1892, date of coUection^ 74 



„ 8 ,, „ -785 (average of 4 examinations) 



)) 12 j» }, 42,537 ,, ,, 



Loch Katrine Water at 9° C. 



Date of Number of micro- 



examination organisms per c.c. 



On July 6, 1892, date of collection ^ 74 



„ 8 „ „ 785 (average of 4 examinations) 



M 12 „ „ 14,462 



' From July 6 to July 8 the water remained in stoppered bottles at about 12'^ C. ; on July 8 

 it was transferred to flasks plugged with cotton-wool, placed in the incubator, and kept at about 

 19° C. until July 12. 



■ In this series the water, instead of being placed in the incubator, was removed to a refrige- 

 rator, and kept at about 9° C. until July 12. 



^ ' Experiments on the Vitality and Virulence of Sporiferous Anthrax 

 in Potable Waters,' Proc. Boy. Soc. 1893, p. 222. 



