32 CONDITIONS OF BACTERIAL LIFE. 



membranes from Uschinsky's solution. How easy it 

 would be for an author to pronounce the cholera of Paris 

 among this number, as a distinct species, since, upon 

 Uschinsky's medium, it contains almost double the amount 

 of albumin which the Hamburg cholera does. 



Bacterial spores have not so far, to my knowledge, been 

 closely studied. One may naturally expect a decreased 

 water-content, from the analogy to the spores of molds. 



C. Rapidity of Increase and Duration of 

 the Life of Bacteria. 



Under favorable conditions (see below) bacteria multi- 

 ply very rapidly; according to Buchner, the number of 

 cholera vibriones, under most favorable conditions, is 

 doubled in twenty minutes (C. B. n, 1). Compare also 

 Ficker (C. B. xxm, 1059). 



The duration of the life of bacteria is theoretically un- 

 limited, since from each cell by division two new ones, 

 with unlimited possibilities of division, are produced. 

 Practically, however, in our cultures the case is quite dif- 

 ferent. As pointed out by Gotschlich and Weigang, in a 

 cholera culture (agar-streak) at 37°, even after twenty-four 

 hours the number of live germs is practically reduced, and 

 after forty-eight hours many bacteria are injured by their 

 own products (Z. H. xx, 376). 



D. Conditions of Life of Bacteria. 



U NUTRIENT MEDIA. 



While a number of bacteria have hitherto been met with 

 only in the human or animal organism as parasites, and 

 appear to us as obligate parasites (example, Spirochete 

 Obermeieri), yet most of the parasites can be grown upon 



