306 MICRO-ORGANISMS IN WATER 



cholera epidemic in Hamburg, points out that during 

 the latter half of August 1892 the river at Hamburg 

 sank to the lowest ebb which had been known for 

 many years, consequently the organic matter, together 

 with the salts present, were in an unusually concen- 

 trated condition. 



Knowing as we now do that the cholera organism 

 is placed at the greatest advantage when a high per- 

 centage of salt is present, the particularly brackish 

 condition of the Elbe during the cholera epidemic of 

 1892 is of special interest and importance. 



From what has been said above, it will be seen that 

 the cholera spirillum is far more susceptible to immer- 

 sion in water than is the typhoid bacillus. Thus the 

 experiments conclusively show that in distilled w r ater 

 the cholera spirilla are rapidly destroyed, generally 

 within twenty-four hours, the few exceptional cases in 

 which they have been observed (Nicati and Eietsch, 

 Wolffhtigel and Biedel) to survive for longer periods 

 of time being almost certainly due to appreciable quan- 

 tities of food-materials having been imported into 

 the distilled water along with the spirilla themselves. 

 There appears to be but little doubt that this speedy 

 destruction of these bacteria in distilled water is due to 

 the rapid osmosis which must take place, for it has 

 been shown (Maschek) that if a certain proportion of 

 common salt be added to the distilled water they may 

 survive for a long period of time ; thus a survival of 

 forty days is recorded under these circumstances. 

 Similarly, even in those potable waters which, like 

 that from deep wells in the chalk, contain only a mere 

 trace of organic matter (see Percy Frankland, above), 

 their longevity was much greater than in distilled 

 water, thus substantiating the view that the rapid 

 destruction in distilled water is due rather to the low 



