NUMBER OF BACTERIA IN WATER 



37 



River Thames Water Collected at Hampton. 



Number of Micro-organisms obtained from 1 c.c. of Water. 



Mouth. 

 January 

 February 

 March 

 April . 

 May . 

 June . 

 July . 

 August 

 September 

 October 

 November 

 December 



45,000 



15,800 



11,415 



12,250 



4,800 



8,300 



3,000 



6,100 



8,400 



8,600 



56,000 



63,000 



1887. 



30,800 



6,700 



30,900 



52,100 



2,100 



2,200 



2,500 



7,200 



16,700 



6,700 



81,000 



19,000 



92,000 



40,000 



66,000 



13,000 



1,900 



3,500 



1,070 



3,000 



1,740 



1,130 



11,700 



10,600 



Another example from the river Lea was as follows : 

 River Lea Water Collected at Chingford. 



Number of Micro-organisms obtained from 1 c.c. of Water. 



Month. 

 January 

 February 

 March 

 April . 

 May . 

 June . 

 July . 

 August 

 September 

 October 

 November 

 December 



1886. 



39,300 



20,600 



9;025 



7,300 



2,950 



4,700 



5,400 



4,300 



3,700 



6,400 



12,700 



121,000 



1887. 



37,700 



7,900 



24,000 



1,330 



2,200 



12,200 



12,300 



5,300 



9,200 



7,600 



27,000 



11,000 



31,000 



26,000 



63,000 



84,000 



1,124 



7,000 



2,190 



2,000 



1,670 



2,310 



57,500 



4,400 



" During the summer months these waters are purest as regards 

 micro-organisms, this being due to the fact that during dry weather 

 these rivers are mainly composed of spring water, whilst at other 

 seasons they receive the washings of much cultivated land " (Frank- 

 land). Prausnitz has shown that water differs, as would be expected, 

 according to the locality in the stream at which examination is made. 

 His investigations were made from the river Isar before and after it 

 receives the drainage of Munich : 



Above Munich 



Near entrance of principal sewer 



13 kilometres from Munich . 



22 



33 



No. of Colonies 

 per c.c. 



531 



227,369 

 9,111 



4,796 



2,378 



