44 MORPHOLOGY 



are at hand. One bacterium dividing once every hour in 

 twenty-four hours would produce if uninhibited 16,777,216 

 individuals, in forty-eight hours 281,474,710,656 individuals, 

 and in six days the mass produced, if each bacterium weighed 

 on the average of T^nr^innnn f a milligram, would equal 

 the size of the earth. Uninterrupted division 4 for any period 

 of time beyond or even to twenty-four hours, except in rare 

 cases, is an absolute impossibility. The geometrical pro- 

 gression is not an actual one in the case of bacteria. Long be- 

 fore the cell has multiplied to the extent given in the above 

 figures, the food will have become so reduced, and excretory 

 products will have accumulated to the extent of acting as 

 poisons to the cells themselves and consequently inhibiting 

 fission, so that reproduction will progress much slower than 

 is possible theoretically and will finally cease completely. Not 

 even in an infected body do bacteria multiply uninterruptedly. 

 It is interesting to observe, however, what unlimited powers 

 of reproduction bacteria have, and that we are dealing in the 

 case of these minute plants with a force of almost infinite power. 

 1 The power of growth and reproduction of the bacterial cell 

 is due, in all probability, to the fact that the food of bacteria 

 is highly organized and must be in solution and ready for ab- 

 sorption and assimilation. This organic food is derived from 

 the disintegration of complex animal and plant compounds. 

 Green plants usually manufacture their food from simpler 

 substances (CO 2 , HO 2 , nitrites and nitrates). Animals and 

 fungi use complex organic compounds for food, and before 



