Darwinism 



of us suspect. To cite only one familiar in- 

 stance: The examination of any bundle of fox 

 skins on a dealer's counter or in a trapper's pack 

 will often reveal marked variety in color, fine- 

 ness, and other respects. Variations occur also 

 in deep-seated structures — bones, muscles, and 

 even nerves — as well as in the superficial cover- 

 ing of the body. 



Mr. Darwin had to seek for some force, 

 process, or tendency in nature which would work 

 in wild animals a selection somewhat similar to 

 that practiced by the breeder among domesticated 

 forms. If he could find this, he had every reason 

 to believe that their slight variations would grad- 

 ually accumulate sufficiently to give rise to new 

 species or genera, or even larger groups. Any 

 slight incompleteness in the natural process would 

 only make the accumulation proceed more slow- 

 ly; it would not arrest it completely. Thus the 

 central thought of Mr. Darwin's theory is that of 

 a Natural Selection. This process is the neces- 

 sary result of the struggle for existence. 



All living species tend to increase in geomet- 

 rical progression. If a pair of birds producing 

 four eggs should breed only once in a lifetime 

 and all should survive, the number of indlvid- 



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