THE RATE OF GROWTH 125 



erable period of development behind them, and as we 

 have discovered that the younger the animal the more 

 rapid its growth, we are safe, it seems to me since 

 we have learned that from the tenth to the fifteenth 

 day there is a daily increase of over 700 per cent. 

 in assuming that in yet younger rabbits an increase 

 of 1000 per cent, per day actually occurs. That is 

 not so extraordinary an assumption, for bacteria are 

 known to divide every half-hour, and if the little 

 bacterium divides and grows up to full size in half an 

 hour, and then divides again, it means that within 

 a half-hour one bacterium has become two, and has 

 increased, obviously, 100 per cent.; and if those two 

 again divide as before, we should have four bacteria 

 at the end of an hour an increase of 400 per cent, 

 and at the end of another half-hour, of 800 per cent., 

 and so on ever in geometrical progression. We learn, 

 then, that bacteria may in a few hours add loooper 

 cent, to their original weight, and it is not by any 

 means an exorbitant demand upon our credulity to 

 accept the conclusion that, in their early stages, rabbits 

 and other mammals and birds are capable of growing 

 at least 1000 per cent, a day. If this be true, and it 

 doubtless is true, we can adopt it as a convenient 

 basis for comparison. As we learned from the rate 

 curves, which were projected upon the screen earlier 

 during the hour, the male rabbit gains in one day 

 shortly after birth nearly eighteen per cent. seven- 

 teen and four tenths per cent. and the female rabbit 

 gains nearly seventeen per cent. Now we can 



