ARTIFICIAL AND NATURAL SELECTION 



ANNUAL PLANT PRODUCING TWO 

 SEEDS ONLY. 



YEAR. NO. OF PLANTS. 



I • I 



3 4 



5 . . . . 16 



7 04 



9 . . 256 



11 . . . 1.024 



4.0QO 



160S4 



65.530 



262,144 



1,048,570 



39 



13 

 15 



1; 



10 

 21 



The rate of increase of an animal, each pair pro- 

 ducing ten pairs annually, and each animal living ten 

 years, is shown in the following table : — 



, Vast numbers of eggs are laid by some animals ; 

 1 the conger-eel, for instance, lays 15 millions; the 

 . herring 20,000 ; the oyster from half a million to 16 



• millions ; and a very large oyster may produce even 

 < 60 millions of eggs. Supposing we start with one 

 , oyster and let it produce 16 million eggs, the average 

 » American yield, and let half, or eight millions, be 



• female and 50 on increasing at the same rate ; in the 



