62 THE NEXT GENERATION 



the way. For this reason those with the smallest ears were 

 best fitted to survive, and now we have the modern mole 

 with ears so small that they are not worthy of mention. The 

 change has come about gradually, step by step, through the 

 laws of variation, the struggle for existence, and the survival 

 of the fittest. Nevertheless, none of these laws would be of 

 the slightest value from one generation to the next without 

 that supreme law which forms the fifth and final link to 

 Darwin's chain. 



V. Heredity 



The mere mention of this word carries us back to the first 

 chapters of the book. It calls to mind Andalusian fowls and 

 guinea pigs. It reminds us of all that inheritance does for 

 the next generation and the next, when man selects ancestors 

 and decides to bring about definite changes in animal de- 

 scendants. But remember that Darwin was searching for 

 laws which control the destiny of all descendants, whether 

 their ancestors are selected by man or not. 



No human power ever chose the ancestors of the wild 

 animals of to-day. Nevertheless, Darwin believed that these 

 same ancestors were selected relentlessly by the five laws 

 which controlled their fate — prodigality, the struggle for 

 existence, variation, survival of the fittest, heredity. He be- 

 lieved that all creatures that live to-day are what they are 

 because the laws of nature chose their ancestors for them. 



Now connect the five links and apply the chain to last 

 year's codfish. By the law of prodigality, thousands upon 

 thousands of eggs were laid. Most of these were destroyed 

 before hatching time came. After hatching, the struggle for 

 existence began. By the law of variation these young cod- 

 fish differed from one another as they continued the struggle. 

 By the law of survival of the fittest only those who were 



