496 GENETICS IN RELATION TO AGRICULTURE 
tance of acquired characters and on the other hand in advocacy of the 
doctrine of the creative effect of selection, there appears to be little 
foundation for either of these views when the evidence is analyzed 
critically. 
The moving spirit in the establishment and improvement of the 
American Standard bred has been the demand for fast race horses. 
Throughout the history of the breed performance has been emphasized 
strictly and consistently; the judgment of merit has been based upon 
actual track records, or upon the ability to produce animals of superior 
performing ability. The requirements for registration adopted in 1882 
by the National Association of Trotting Horse Breeders are an eloquent 
testimonial of this. They are given in full below. 
In order to define what constitutes a trotting-bred horse, and to establish a breed 
of trotters on a more intelligent basis, the following rules are adopted to control 
admission to the record of pedigrees. When the animal meets with the requirements 
of admission and is duly registered, it shall be accepted as a standard trotting-bred 
animal. 
First.—Any stallion that has, himself, a record of 2:30 or better; provided any of 
his get has a record of 2:40 or better; or provided his sire or his dam, his grandsire or 
his grandam, is already a standard animal. 
Second.—Any mare or gelding that has a record of 2:30 or better. 
Third.—Any horse that is the sire of two animals with a record of 2:30 or better. 
Fourth.—Any horse that is the sire of one animal with a record of 2:30 or better; 
provided he has either of the following additional qualifications: (1) a record himself 
of 2:40 or better; (2) is the sire of two other animals with a record of 2:40 or better; 
(3) has a sire or dam, grandsire or grandam, that is already a standard animal. 
Fifth.Any mare that has produced an animal with a record of 2:30 or better. 
Sizth.—The progeny of a standard horse when out of a standard mare. 
Seventh,—The progeny of a standard horse when out of a mare by a, standard 
horse. 
Highth.—The progeny of a standard horse when out of a mare whose dam is a 
standard mare. 
Ninth.—Any mare that has a record of 2:40 or better, and whose sire or dam, 
grandsire or grandam, is a standard animal. 
Tenth.—A record to wagon of 2:35 or better shall be regarded as equal to a 2 :30 
record. 
These are rules well calculated to sort out and preserve the most 
excellent lines of descent. That they have operated by discovery and 
utilization of unusually excellent genotypes is rather strikingly indicated 
by a study of some of the famous families of standard-bred animals. In 
Table LXIV E. Davenport has presented data relative to the ten greatest 
producers of speed in the history of American racing up to and including 
1901. Without exception these ten sires belong to the famous Hamble- 
tonian family of racing horses. They are all descendants of Hamble- 
tonian 10: for Belmont 64 is a grandson of Hambletonian 10, and Geo. 
Wilkes and Happy Medium were both sons of Hambletonian 10. Within 
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