Much of the recent stimulus to the study of the Science of Breeding
was occasioned by the discovery of Mendel's Law. Briefly, the law
states that when two pure traits or characters are crossed, one
dominates in the first generation of offspring--the other remaining
hidden or recessive. Of the second generation, one-half the
individuals are still mixed, bearing the dominant characteristic
externally and the other hidden; one-fourth are pure dominants and
one-fourth are pure recessives. In future generations the mixed or
hybrid individuals again give birth to mixed and pure types
apportioned as before, thus continuing until all offspring become
ultimately pure. For illustration: If rose and single comb chickens
are crossed, rose combs are dominant. The first generation will all
have rose combs. The second generation will have one-fourth single
combs that will breed true, one-fourth rose combs that will breed
rose combs only, and one-half that again will give all three types.
Mendel's Law works all right in cases where pure unit
characteristics are to be found. For the great practical problems in
inheritance, Mendel's law is utterly hopeless. The trouble is that
the chief things with which we are concerned are not unit
characteristics but are combinations of countless characteristics
which cannot be seen or known, hence cannot be picked out. Thus the
tendency to revert to pure types is foiled by the constant
recrossing of these types.
Mendel's law is a scientific curiosity like the aeroplane. It may
some day be more than a curiosity, but both have tremendous odds to
overcome before they supplant our present methods.
Prof. C.B. Davenport, of the Carnegie Institute, is working on
experimental poultry breeding in its purely scientific sense. His
conclusions have been much criticised by poultry fanciers. The truth
of the matter is that the fancier fails to appreciate the spirit of
pure science. The scientist, enthused to find his white fowl
re-occur after a generation of black ones, is wholly undisturbed by
the fact that the white ones, if exhibited, might be taken for a
Silver Spangled Hamburg.
Mendel's law as yet offers little to the fancier and less to the
commercial poultryman. Its study is all right in its place, but its
place is not on the poultry plant whose profits are to buy the baby
a new dress.
Breeding for Egg Production.
Attempts to improve the egg-producing qualities of the hen date from
the domestication of the hen, but it has only been within the last
few years that rapid progress has been possible in this work. The
inability to determine the good layers has been the difficulty.
Public-domain text, read in full here on John Shaqi.
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