22 FARM ANIMALS 



is evident that were it not for the tendency towards 

 variation it would be impossible to improve upon 

 native stock or upon our present breeds to any 

 great extent. Variation furnishes suggestions of 

 valuable tendencies, which after being noticed 

 are seized upon and perpetuated through heredity. 

 In breeding animals the tendency is sometimes ob- 

 served in offspring to "throw back" or to develop 

 characteristics which do not appear in the parents 

 but rather in grandparents or some other more re- 

 mote ancestor. This is known as atavism and 

 sometimes interferes to a slight extent with the 

 efforts of the breeder but cases of atavism are, 

 as a rule, extremely rare. 



Among the various myths which have grown up 

 around the subject of breeding we may mention 

 those concerning maternal influence and the influ- 

 ence of a previous sire. Many writers have argued 

 and thousands of instances have been collected to 

 prove that experiences of the mother animal during 

 pregnancy may produce definite effects upon the 

 offspring. This matter has been investigated quite 

 extensively and innumerable instances of this sort 

 have been compiled. It is sufficient to say re- 

 garding this matter that no unquestionable evidence 

 of any such case has ever been shown. Similarly 

 with the belief in the influence of a previous sire, we 

 find a great deal of talk mixed up with supposed 

 observations of fact. It has been quite generally 

 believed by breeders of pjigs, cattle, horses, chickens 

 and other animals that if a pure bred female bear 

 offspring to a mongrel male or male of another 

 breed, the influence of this male will always be 

 manifest in subsequent offspring from other males 

 or that such animals after once being " contamina- 

 ted " can never again bear pure offspring. Recently 



