II THE ORIGIN OF SPECIES 41 



same direction ; while, in the other, no race was 

 evolved, because no such selection was exercised. 

 A race is a propagated variety ; and as, by the laws 

 of reproduction, offspring tend to assume the 

 parental forms, they will be more likely to pro- 

 pagate a variation exhibited by both parents than 

 that possessed by only one. 



There is no organ of the body of an animal 

 which may not, and does not, occasionally, vary 

 more or less from the normal type ; and there is no 

 variation which may not be transmitted, and which, 

 if selectively transmitted, may not become the 

 foundation of a race. This great truth, sometimes 

 forgotten by philosophers, has long been familiar 

 to practical agriculturists and breeders ; and upon 

 it rest all the methods of improving the breeds of 

 domestic animals, which, for the last century, have 

 been followed with so much success in England. 

 Colour, form, size, texture of hair or wool, pro- 

 portions of various parts, strength or weakness of 

 constitution, tendency to fatten or to remain lean, 

 to give much or little milk, speed, strength, tem- 

 per, intelligence, special instincts ; there is not one 

 of these characters the transmission of which is not 

 an every-day occurrence within the experience of 

 cattle-breeders, stock-farmers, horse-dealers, and 

 dog and poultry fanciers. Nay, it is only the other 

 day that an eminent physiologist, Dr. Brown- 

 Sequard, communicated to the Royal Society his 

 discovery that epilepsy, artificially produced in 



