220 



MICRO-ORGANISMS IN WATER 



That this was the case the following experiments 

 illustrate very clearly : — 



Description 



River Thames at Hampton . 

 River Lea at Cliingford 



Number of bacteria in 1 c.c. 



On day of 



collection, 



temp, of 



water 8° C. 



Aiter stand- 

 ing in dark 



at 20° C. 



for 2 days 



Ditto after 

 4 days 



12,250 

 7,300 



4,386 

 2,148 



2,018 

 1,286 



The organisms in the raw river-water thus under- 

 went a marked reduction after storing for two and four 

 days respectively in stoppered bottles.^ But if these 

 waters are kept in the incubator at a high temperature 

 [ob^^ C), the reverse takes place in the first instancCj 

 thus : — 



Description 



River Thames at Hampton 



Thus a very rapid increase in the numbers present 

 took place at first, but an exposure of eight days to 



^ It should be pointed out that in these experiments with untiltered 

 river-water the initial number of bacteria present was very large. We 

 have subsequently found that when the initial numbers are smaller and 

 the water is preserved in flasks to which there is free access of air through 

 cotton-wool stoppers, the multiplication may be very extensive. This 

 result is, moreover, in precise accordance with the experiences of Miquel 

 on the water of the Seine, in which connection he remarks : — ' De Teau 

 de la Seine, puisee ii Ivry pendant I'ete, d'lone richesse inferieure h. la 

 moyenne annuelle, petit presenter des recrudescences de germea assez 

 elevees ; elle montre ^ cet egard une tendance manifeste ^ se comporter 

 comme les eaux de source ; mais que surviennent les crues, que sa teneiir 

 en microbes atteigne 'X I'analyse immediate 20,000 et 30,000 bactdries par 

 centimetre cube, cette faculte de s'infester spontan^ment disparalt, et cette 

 eau, impure ne pent devenir le si^ge de recrudescences microbiennes 

 rapides et soudaines.' 



