150 Ei'olution of Animal Life. 



" The Vestiges of Creation") and others. But the notion 

 that changes produced in the individual could be accumu- 

 lated by simple inheritance into permanent specific struct- 

 ural peculiarities, was rejected as inadequate. So indeed it 

 Avas, standing alone; but as factors in derivation, according 

 to our present conception of that process, the Lamarckian 

 or interior resident forces are gaining wider recognition. 



Darwin's theory includes H, but is based mainly on /to 

 P inclusive, with A and B. We might symbolize it as fol- 

 lows, taking care not to attach a mathematical meaning to 

 our equations : 



(1) MN=L 



(2) LO=P 



n^) L— P=M= 



^ ^ KO 



(4) MI=^ 



(5) -jJ^ [-AB=AQ=E. 



^ < KO > 



Or in words : 



1. The number of individuals in a given generation of a 

 species, who complete the functions of life, produces by the 

 law of multiplication the number which Avill comiaete for 

 similarly complete life in the next generation. 



2. In this multiplied offspring, competition causes the 

 premature death of the majority. 



3. The remainder constitutes 'the effective population 

 for that generation, and since it will tend to consist of those 

 individuals best fitted for N, it will be the result of individ- 

 ual differences according to K, and will constitute a fraction 



of L, determined by K and O. is therefore a symbol 



^ KO 



for "the survival of the fittest." 



4. The population of the fittest survivors, thus preserv- 

 ed, will tend through / to intensify its advantageous pecu- 

 liarites, in each succeeding generation. 



5. This process, continued long enough (^A) under the 

 changes of environment (J5), will produce results like those 

 of artificial selection, and moreover, will bring about, as ar- 

 tificial selection might do if continued long enough, true 

 physiological species, characterized by intersterility. 



