BACTERIA AS PLANTS. 



21 



spiral forms. Here, too, we find short rods and 

 long chains, or long spiral filaments in which can 

 be seen no division 

 into shorter elements, 

 but which, under cer- 

 tain conditions, break 

 up into short sections 

 (Fig. 8). 



RAPIDITY OF 

 MULTIPLICATION. 



It is this power of 

 multiplication by di- 

 vision that makes bac- 

 teria agents of such 

 significance. Their 

 minute size would 

 make them harmless 

 enough if it were not 

 tor an extraordinary 

 power of multiplica- 

 tion. This power of 

 growth and division 

 is almost incredible. 

 Some of the species 

 which have been care- 

 fully watched under 



the microscope have been found under favourable 

 conditions to grow so rapidly as to divide every 

 half hour, or even less. The number of offspring 

 that would result in the course of twenty-four 

 hours at this rate is of course easily computed. 

 In one day each bacterium would produce over 

 16,500,000 descendants, and in two days about 

 281,500,000,000. It has been further calculated 



FIG. 8. Various types of spiral 

 bacteria. 



