464 GENETICS IN RELATION TO AGRICULTURE 
the horned condition; so that, given a polled individual, it is the simplest 
kind of a Mendelian problem to establish a race all the individuals of 
which are polled. 
From the more strictly economic side there is very slight evidence of 
the occurrence under observation of any definite mutation. Arenander 
reported some results with milk cows which might indicate mutation. 
The evidence deals with a cow Ortvart and her progeny. This cow 
gave milk of an abnormally low fat content, and she transmitted this 
character to her daughters. But nothing definite is known as to the 
parentage of Ortvart. Furthermore she was as strikingly distinct in 
color characters as in low fat content of the milk; she was white with 
black ears and small spots. Of her seven daughters five are described 
as of the same color and pattern, the remaining two were of the same 
pattern but the ears and spots were red. There is no acceptable evidence 
of mutation in this case, but the evidence of inheritance of the trait of 
producing milk of low fat content is unmistakable. So also Pearl’s 
case of a mutant in egg production is, probably, as he himself states, 
merely a case of extreme Mendelian segregation. The data for this 
case are given in Chapter XXXI. We may conclude, therefore, and 
rightly, that any system of herd improvement founded on the search 
for and utilization of mutants is doomed frem the beginning to failure, 
for mutants of a beneficial character appear so rarely as to have almost 
no practical significance. If by some fortunate chance a breeder should 
find himself in possession of a favorable mutant individual, however, 
it is a simple problem in Mendelism to establish its characters in a 
constant race, 
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