BACTERIA 



may be watched under the microscope. The plant 

 elongates somewhat, it becomes narrower and 

 narrower in the middle, it develops a waist in fact ; 

 finally the two halves part company and each one 

 leads a separate existence as a bacterium. This 



1 splitting progresses at an extraordinary rate. A 



; celebrated scientist once wrote ; ** Let us assume 

 that a microbe divides into two within an hour, 

 these two into four in the next hour, these again 

 into eight in the third hour and so on. The number 

 of microbes thus produced in 24 hours would ex- 



\ ceed 16j millions ; in two days they would increase 

 to 47 trillions, and in a week the number expressing 

 them would be made up of 51 figures. At the end 

 of a day (24 hours) the microbes descended from 

 a single individual would occupy one fortieth of a 

 hollow cube with edges one twenty-fifth of an inch 

 long, but at the end of the following day would 

 fill a space of twenty-seven cubic inches, and in less 

 than five days their volume would equal that of the 

 ocean." It is hardly necessary to add that these 

 alarming figures represent what would happen if no 

 accident befel the bacteria, they show the enormous 

 vitality possessed by the smallest of all plants. 

 Even allowing for misadventure their increase is 

 ilarming; actual tests, with a sample of milk con- 



';:aining originally 153,000 bacteria per cubic inch, 



:?how that the cubic inch contained after one hour, 



539,750; after two hours, 616,250; after seven hours, 



1,020,000; after nine hours 2,040,000 and after 



J5 hours 85,000,000 individuals. 



157 



