DARWIN'S THEORY. 23 



individuals presenting any modification, or improve- 

 ment ; and from Man's judicious pairing of such indi- 

 viduals, with others with like variations. In this way, 

 the " tendency to vary," by being combined in pairs 

 which similarly vary, is strengthened, and fixed ; and 

 an increase in the quality and quantity of the modi- 

 fications, is insured in the offspring. 



By this preservation, and accumulation, of slight, 

 successive, scarcely appreciable modifications, most dis- 

 tinct varieties are formed ; and great differences result, 

 between the individuals of the same species. Where- 

 as, if Man's intervention did not interpose, the individ- 

 uals of each of these species would all be of one, uni- 

 form character ; and the improvements which did arise, 

 would be sunk again, by the varying individuals' inter- 

 crossing with others, of the same species, which had no 

 like tendency to vary, or which had tendencies of growth, 

 perhaps, adverse to the continued development of the 

 said improvements. Under domestication, however, the 

 individuals, similarly varying, are interbred. Favora- 

 ble changes are noted by the breeder, or fancier ; care- 

 fully preserved ; and further developed, by the mating 

 of such individuals, with others displaying a tendency 

 to a like change of character. The individuals, which 

 display no variation, or which develop changes, or vari- 

 ations, which are not the recognized peculiarities of 

 their varieties, are neglected or suppressed. If this 

 process of Man's selection were not employed, those 

 individuals, not varying, being in the majority, would 

 most probably run out the varying ones, or completely 

 negative, or nullify, the tendency to vary, in others, by 



