The Editor: Concerning Prepotency 
cross is wholly parallel to the illustration 
of Brigham Young and his daughters; 
I am still of the opinion that the daugh- 
ters, despite the fact that they come 
from eight different mothers, resemble 
each other as much as do ordinarily 
the children of a single mother; and I 
am of the opinion that the father may 
therefore properly be called prepotent, 
as the term is ordinarily used. It 
seems to me that the uniformity of 
mouth, nose and ears furnishes a good 
illustration. But I certainly would 
not lay much weight on the illustration 
as an evidence of the existence of either 
character prepotency or individual pre- 
potency; it is nothing more than an 
illustration, although as good a one as 
I have ever seen in human material. 
To get any real light on the problem, 
I think we must stay in the field of live- 
stock breeding, where the problem arose. 
MR. ROMMEL’S OPINION 
To get light here we called on the 
secretary of the American Genetic 
Association for information as to the 
attitude of intelligent modern breeders; 
he was asked particularly whether in re- 
gard to individual prepotency geneticists 
had from their more limited experience 
overlooked a principle recognized among 
practical breeders. His reply is as 
follows: ‘Concerning individual pre- 
potency, I will say that this has been 
made the subject of two of the regular 
Saturday afternoon conferences of the 
officers of the division. It is the con- 
sensus of opinion that from the stand- 
point of the geneticist there is no such 
thing as individual prepotency in ani- 
mals; that is to say, that no animal is 
prepotent in every character. There 
have been many animals that were‘ pre- 
potent in certain characters, or even 
in many characters. From the stand- 
point of the practical breeder there is 
individual prepotency in that certain 
animals have been prepotent in pro- 
ducing the things for which the breeder 
is striving. 
“The inbreeding by which a char- 
acter of interest is made prepotent will 
automatically make the factors affect- 
ing other characters homozygous, will 
give some prepotency to these characters 
333 
(as far as they are due to dominant 
factors), and will give the individual an 
appearance of individual prepotency. 
“As an example may be mentioned’ 
the case of the Standard-bred stallion, 
Peter the Great, 28955. He has 216 
sons and daughters with records of 2.30 
or better. This is a good example of 
prepotency in the matter of speed and 
included with this must be various 
other characters, not measurable per- 
haps, which enable these horses to go 
a mile in such fast time. 
“There are on record a few other 
stallions which have more sons and 
daughters with records of 2.30 or better, 
but none of these stallions is. living 
at the present time. 
“As other examples may be mentioned 
famous Holstein and Guernsey bulls, 
famous because of the fact that they 
have sired a large number of daughters 
which have made records large enough 
to admit them to the Advanced Register. 
In order to make these records these 
animals must have had the requisite 
constitution, capacity, and nervous tem- 
perament, without which such records 
would not have been possible. The 
sires were undoubtedly prepotent in 
such characters but these are not 
measurable. 
“One of the best examples of pre- 
potency in beef cattle is that of the 
Shorthorn bull Avondale. This bull 
has sired a large number of excellent 
bulls and heifers indicating that he was 
prepotent in a large number of char- 
acters. 
“T trust that this statement will give 
you a clear idea of what is in our minds; 
I think that it is the idea in the minds 
of practical breeders. 
“Very truly yours, 
““Geo. M. RoMMEL, 
“Chief, Animal Husbandry Division, 
U.S. Department of Agriculture.” 
Evidently, then, the idea of individual 
prepotency which the breeders hold, and 
by which they mean that a certain 
animal has superior influence in hered- 
itary transmission, covers many causes 
or supposed causes. Thus in one con- 
nection or when used by one person it 
may mean (as it actually does in 
