6 MODERN DAIRY PRACTICE. 



in case of some bacteria that the time elapsing between the 

 division of the mother bacterium and the moment when 

 the new bacterium in its turn begins to multiply amounts 

 to only twenty minutes. As a rule the interval may not 

 be as short, but it often does not amount to more than 

 about an hour. A bacterium which grows and divides 

 into two organisms during this time may, under ideal con- 

 ditions, within 24 hours be the ancestor of 16,777,214 or- 

 ganisms. A sarcina which produces, e.g., eight new bac- 

 teria in an hour by dividing in three directions, may after 

 20 hours have an offspring so enormous that it is 1,111,- 

 152,347 times larger than the number of human beings 

 found on our planet; the figure indicating the number of 

 this progeny would contain nineteen ciphers I 



As a corollary of this enormously rapid multiplication 

 it follows that the bacteria in general must exist in nature 

 under highly unfavorable conditions, as they would other- 

 wise soon fill the whole earth and annihilate everything 

 else living. 



5. Multiplication ~by Spores. The multiplication 

 through spores (Figs. 10-11) occurs in the manner that 

 small round or egg-shaped bodies with a characteristic 

 power of refraction are formed within the bacterium, and 

 later on these grow to ordinary bacteria, under proper condi- 

 tions of heat and moisture. The spores possess far greater 

 power of resistance against drought, heat, cold, etc., than 

 do the bacteria themselves. The fact that these often 

 prove almost indistinguishable from the material to which 

 they have once gained access depends in most instances 

 on the fact that spores have been formed there. If, e.g., 

 sporeless bacteria dry up, they die comparatively soon, 

 within a day, or perhaps a week. If the conditions are 



