96 HEREDITY. 



ever remain unchanged; both evolution and de- 

 terioration would be impossible. If the second 

 law were the only one, or even the controlling 

 factor, then the environment and conditions of 

 each generation would so modify the next as to 

 destroy all established types and finally extermin- 

 ate the species. By the continued operation and 

 opposition of these two laws, gradual change and 

 continued evolution are rendered possible. By 

 the conservative principle nature retains all that 

 it worth saving of the species ; while by the radical 

 principles she modifies species by giving to off- 

 spring what was acquired by parents. 



Through the law of heredity theoretically 

 speaking at least each member of a species re- 

 ceives an influence from all its ancestors clear 

 back to the primal cell whence it sprang. The man 

 MananEpitoniy ^ to ~day is the sum total of all that has preceded 

 him. Whatever changes have been wrought by 

 the evolution of the earth and its relation to the 

 other members of the solar system; by develop- 

 ing life in its struggle for existence and its strug- 

 gle for the existence of others ; by natural selec- 

 tion and the survival of the fittest; by sexual se- 

 lection and the mating instinct; by use and dis- 

 use ; by the mixing and crossing of races and na- 

 tionalities; by the combining of families and the 

 transmission of acquired characters; by the in- 

 fluences of food, climate, habit, custom, law, com- 

 merce, society, education and religion; all are 

 recorded and interwoven into the life of the man 

 of to-day. 



By heredity the product of all these factors in 

 man's evolution has been retained and transmitted 



of the Race. 



