DARWIN'S THEORY 11 



he submitted to the Linnaean Society of London an abstract 

 of his own conclusions, which was read and pubhshed simul- 

 taneously with the paper by Wallace. The work of each 

 author was so manifestly independent of the other and each 

 dealt so generously with the other that no rivalry arose 

 between them, and both were to the last the best of friends. 

 The essential points in their theory, which Darwin elabor- 

 ated more fully the following year (1859) in his Origin of 

 Species, have been summarized thus by Conn (p. 353) : 



" 1. Overproduction, All animals and plants tend to 

 multiply more rapidly than it is possible for them to continue 

 to exist. More offspring are produced by even the slowest 

 breeding animals and plants than can possibly find susten- 

 ance in the world. 



" 2. Struggle for existence. As a result of overproduction, 

 the individuals that are born are engaged in a constant 

 struggle with each other for the opportunity to live. This 

 struggle is sometimes an active, sometimes a passive one; 

 and sometimes it is a struggle with each other for food. It 

 is a struggle in which only the victors remain alive, the 

 vanquished being exterminated without living long enough 

 to leave offspring. 



" 3. Variation, or diversity. All animals and plants show 

 a large amount of diversity among themselves, and, as a 

 result, some must be better fitted for the struggle for life 

 than others. 



''4. Natural selection, or the survival of the fittest. It is a 

 logical result of the struggle for existence that only those 

 individuals best fitted for the struggle will be the ones, in 

 the long run, to win in the contest. Hence the " fittest " 

 in the long run will survive, while those less fitted to exist 

 will be exterminated. 



"5. Heredity. By the laws of heredity, individuals trans- 

 mit to their offspring their own characters. Hence if one 

 individual survives the struggle for existence by virtue of 

 some special characteristic, it will transmit this characteristic 

 to its offspring. The offspring will inherit it, and in the 



