?0 CONDITIONS OF BACTERIAL LIFE. 



4. DEFICIENCY OF NOURISHMENT AND 

 WATER, 



If bacteria which require substrata rich in nourishment 

 in order to thrive (including most pathogenic) are placed in 

 pure distilled water, they usually die rapidly — i. e., in an 

 hour. As Ficker (Z. H. xxix, 1) pointed out, numerous 

 minute influences here become accentuated. Thus, traces 

 of nutrient material, even long standing in glass vessels, 

 especially boiling in glass vessels, suffice to lessen the 

 bactericidal action of distilled water. Jena glass is espe- 

 cially recommended for control investigations, since it gives 

 up almost nothing to distilled water. Dense suspensions 

 and virulent cultures are more slowly destroyed; the age 

 of the individuals is indifferent. In well-water (even if 

 sterilized) the duration of life is usually not more than 

 eight to fourteen days, and an increase is rare. Certainly, 

 in a series of cases, much longer duration of life is observed, 

 but here the conditions mentioned above, and until now 

 usually neglected, come into question. Leipzig tap-water, 

 which remains long in pipes, is strongly germicidal, but 

 after being boiled it loses a part of this action, etc. (Com- 

 pare Ficker, I c. , and Loffler : Das Wasser und die Mikroor- 

 ganismen, 1896.) Deficiency of water exerts a disturb- 

 ing influence upon bacterial growth. My pupil, Leo Wolf 

 (A. H. xxxiv, 200), found that upon various nutrient 

 media (agar, gelatin, pulverized meat, cake), with 70% 

 and more of water, growth was most vigorous, with 60% it 

 was often interfered with, with 50% it was usually slight, 

 and when only 40% of water was present there was often 

 no growth to be detected, macroscopically at least. On 

 the contrary, upon nutrient media (agar, gelatin, potato) 

 dried gradually at room temperature, the duration of 

 life is often astonishingly long, even when there are no 

 endospores present to be responsible for it. At times one 

 may observe that even after a year a horny contracted rem- 

 nant of a culture upon being placed in bouillon (and with 

 proper varieties kept in an incubator) yields a most beau- 

 tiful growth. 



Regarding the duration of life of bacteria, when they 

 are spread upon glass and dried, the literature contains 



