DEVELOPMENT OF THE BACTERIA. 125 
divides into two in the space of an hour, then in 
four at the end of a second hour, then in eight 
at the end of three hours, in twenty-four hours 
the number will already amount to more than six- 
teen millions and a half (16,777,220); at the end 
of two days this bacterium will have multiplied 
to the incredible number of 281,500,000,000; at 
the end of three days it will have furnished forty- 
seven trillions; at the end of about a week, a 
number which can only be represented by fifty-one 
figures. 
“In order to render these numbers more com- 
prehensible, let us seek the volume and the weight 
which may result from the multiplication of a 
single bactertum. The individuals of the most 
common species of rod-bacteria present the form 
of a short cylinder having a diameter of a thou- 
sandth of a millimeter, and in the vicinity of one five 
hundredth of a millimetre in length. Let us rep- 
resent to ourselves a cubic measure of a millimetre. 
This measure would contain, according to what we 
have just said, 633,000,000 of rod-bacteria with- 
out leaving any empty space. Now, at the end 
of twenty-four hours the bacteria coming from 
a single rod would occupy the fortieth part of a 
cubic millimeter; but at the end of the follow- 
ing day they would fill a space equal to 442,570 
of these cubes, or about a half a litre. Let us 
admit that the space occupied by the sea is equal 
to two-thirds of the terrestrial surface, and that 
its mean depth is a mile, the capacity of the ocean 
will be 928,000,000 of cubic miles. The multipli- 
