26 SOC^IAL EVOLUTION 



real germinal variation. AVhatever its cause, as long 

 as the variation gives advantage in the struggle, the in- 

 dividual which possesses it, has a greater chance to sur- 

 vive, and surviving, to transmit it to his offspring. Oc- 

 casionally, characters seem to go together in bundles; 

 as such, they are often of advantage and are inlierited. 

 Some variations from the general type of the race are. 

 not transmitted. Yai'i^i^hms of tlic mutation kind are 

 inherited. If then, a mut.itinn i;i\(> advantage to the 

 individual possessing it, that individual will most prob- 

 ably survive while others not possessing the favorable 

 trait will be at a disadvantage. But survival means not 

 simply the fact of a safe and unhindered enjoynu>nt of 

 life. It means the bearing and rearing of youngy Bio- 

 L^gically, survival means that the individual reaches ma- 

 t_ui'ity and has offspring to which he transmits th& favor- 

 a ^)le c haracteristics that aided him in the struggl^ 

 \The struggle will usually be ''most severe between in- 

 dividuals of the same species, for they frequent the 

 same districts, require the same food, and are exposed 

 to the same dangers." In such a case the most minute 

 variation may determine which will survived As many 

 variations seem to be the result of pure chance, so sur- 

 vival is in many instances the result of pure chance. An 

 illustration will make this clear. Dr. C. B. Davenport 

 of the Carnegie Institution for Experimental Evolution, 

 placed 300 chickens in an open field. Eighty per cent, 

 were white or black and hence conspicuous ; 20 per cent, 

 were spotted and hence inconspicuous. In a short time 

 twenty-four were killed by crows, but only one of the 

 killed was spotted. The white and black chickens were 

 easily discernible to the crows and hawks flying over- 

 head, and they swooped down and carried off twenty- 



