THE BREEDING OF HORSES 181 



There are usually a few individual ancestors who, by their 

 great prepotency, dominate the ancestry and have more than 

 their regular fractional influence in determining the nature of 

 the progeny. The more of such impressive ancestors there are, 

 provided their impressiveness is along the same line, the stronger 

 the transmission of their characters will become. Line, or in- 

 breeding, is practiced with this in view, the same individuals 

 being used as many times as possible, thus intensifying the 

 hereditary transmission of their characters. 



The germ plasm, representing the union of the two sex cells, 

 is the physical basis of heredity. It represents both the char- 

 acters of the ancestry which are dominant in this generation, and 

 will therefore be manifested by the individual developed from 

 the germ plasm, and the potential characters of the entire an- 

 cestry, which may remain recessive in this generation and not 

 be manifested in this particular individual, but may, in the next 

 succeeding generations, become dominant, some in one indi- 

 vidual descendant and some in another. Thus the unlikeness of 

 brothers may be accounted for. 



Transmission is, therefore, not from the individual parent 

 but from the ancestry through the parent. The individual mani- 

 fests but a part of the characters which he inherits, and is con- 

 sequently capable of transmitting characters which he himself 

 does not possess. All the possibilities of transmission can be 

 learned only by a study of tlie ancestry. Unkno^v^l individuals 

 in the ancestry introduce unknown possibilities into the progeny, 

 hence the advantage of the pure-bred parent, the known excel- 

 lence of whose ancestry is established. A superior but short-bred 

 individual may happen to manifest all the good qualities of his 

 or her ancestors but transmit none of them. A lack of uniformity 

 in the ancestry is sure to result in a miscellaneous progeny. 

 However, registration and pure breeding are not sufficient, as 

 inferiority possessed in uniform degree by the ancestors will 

 render the progeny of a correspondingly low order of merit; and 

 even some pure-bred and registered horses are inferior in both 

 individuality and anccstiy. 



Pedigree is but a record of the ancestry, and the value of the 

 pedigree, provided it is complete in recording all ancestors of 



