184 HEREDITARY CHARACTERS 



with the production of characters under normal conditions. 

 It seems reasonable in fact to regard many of these char- 

 acters as exaggerated individual variations. If this con- 

 ception be correct, it would seem probable that individual 

 variations are transmitted according to the law of Mendel. 



Individual characters are either individual variations, or 

 characters inherited from a parent which are not common to 

 the race, but are confined to individuals that have inherited 

 a variation from a near ancestor. It is probable, then, that 

 individual characters are transmitted in an alternative or 

 Mendelian manner, and that racial characters tend to blend. 



The alternative distribution of individual characters or 

 variations, would make two results quite certain under 

 natural conditions. (1) That useless variations would be 

 eliminated in a very short time by the action of bi-parental 

 reproduction. (2) That individual variations that are the 

 subjects of selection would be much more readily pre- 

 served and characters be more quickly produced from 

 them, than if the variations blended. 



It is necessary to examine this hypothesis in some detail 

 in order to realise the extent to which it coincides with the 

 known facts of hereditary transmission. 



If the characters in domesticated races that are trans- 

 mitted in the Mendelian manner are really individual 

 variations exaggerated by man's interference, we ought to 

 find that only some characters in domesticated races are 

 alternative, while others are not, and do not tend to 

 segregate in succeeding generations. This is probable, 

 because man can hardly have applied his selection to 

 many characters at the same time. The other characters 

 of which he took no notice would be subjected to the 

 influence of bi-parental reproduction, and also to a limited 

 extent to natural selection. With regard to the particular 

 characters which he had selected, the greatest purity ought 

 theoretically to be met with in the case of self-fertilising 

 organisms, and the least purity in those where most crossing 

 is necessary. It is a matter of common knowledge that 



