lO The Life Story of the Fish 



eating leaves and survived. The long neck being a constitu- 

 tional, genetic characteristic, and not an acquired one, it 

 passed on by inheritance to the next generation. And once 

 the giraffe had become a tree-grazer the neck tended to 

 become longer through selection. For the individual who 

 happened to have a longer neck than the average obtained 

 more food, grew stronger, had a better chance of securing 

 mates, and produced more offspring than the others, and 

 those of the offspring which inherited the parental neck 

 flourished and produced in turn a disproportionate number 

 of offspring, who inherited and passed on that neck. The 

 shorter-necked individuals, being unable to compete for 

 food, were weak, and died early and childless, and so the 

 species continued to lengthen its neck until the point was 

 reached where the feeding advantage of additional length 

 was overbalanced by unwieldiness and weight, and there the 

 process stopped. And the result is the present-day giraffe. 



Or, to come back to our subject, the mutationist does not 

 believe that the pickerel acquired his mottled coloration by 

 hiding in the weeds until he came to resemble them. He 

 believes that certain primordial pickerel chanced to have 

 that mottling, and were therefore able to hide more success- 

 fully in the weeds than their fellows, and to snap up more 

 primordial bass and trout fingerlings. These individuals 

 grew larger and stronger than the rest, and were thus en- 

 abled to monopolize the food and the mates, and to have 

 more children. And while not all of their children inherited 

 this peculiarly successful coloration, those which did not 

 failed to prosper, and from generation to generation grew 

 fewer until eventually only the present-day pickerel survived. 



While at first sight this theory of the mutationists seems 

 far-fetched and the importance it places on the part played 

 by chance distasteful, it has one great advantage: it does 

 provide a mechanism which is capable of accounting for the 



