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INSTRUCTION IX ANIMAL BREEDING. 
As long as animal breeding is included in the curriculum of every agricultural 
college, just so long will there be a crying need for careful observations on certain 
phenomena, and just bo long will there be need of accurate observations to determine 
the truth or fallacy of certain questions of breeding. There is perhaps no subject 
taught in our agricultural colleges that is so largely based upon unreliable and 
unscientific data. Our present knowledge of breeding is based upon chance obser- 
vations, mostly by untrained observers. No systematic effort has so far been made 
to investigate* these breeding problems with the definite purpose of formulating 
fundamental general principles. 
The embryologists and cytologists have given us some valuable suggestions as to 
the real problems of heredity, but they have not furnished any satisfactory solution 
of many of the mysterious and intricate questions of heredity. Many of the observed 
phenomena bring about changes in the developing embryo too minute to be observed 
by any present methods of investigation at our command. In this connection the 
investigation of Sutton and others on the individuality of the chromosomes, and the 
work of Guyer on spermatogenesis of hybrids, should be remembered. These inves- 
tigations point to a cytological explanation of Mendel's law. 
PROPER SUBJECTS OF INVESTIGATIONS. 
It may be stated at the outset that there are certain questions which are not in the 
present 'state of our knowledge proper subjects for investigation. The peculiar con- 
ditions by which they are surrounded makes the securing of valuable data exceed- 
ingly improbable. We need at the present time carefully planned and executed 
experiments where all the conditions can be controlled. I can not hope at this time 
to even suggest all of the fruitful lines which might be undertaken by investigators 
in animal breeding, but I venture to call your attention to certain classes of facts 
which it seems to me are proper subjects of investigation and upon which the experi- 
ments of the animal breeder may throw some light. 
The one quality most desired, and from every standpoint most important in our 
improved breeds of live stock, is prepotency. The ability of a well-improved animal 
type to perpetuate its improved qualities is the most valuable character it can possess. 
In a breeding animal all other qualities sink into insignificance in the absence of this 
power of transmission. I believe, therefore, that an investigation of prepotency 
should form the foundation stone of a rational series of breeding experiments. In 
investigating the conditions which control or influence prepotency we must study 
the influence of limited inbreeding, continuous in-and-in breeding, cross breeding, 
telegony, the relative influence of parents, the age of the animal, and their physical 
condition at the time of mating; but an investigation of these questions has to do with 
the fundamental principles of stock breeding. The results secured from such a series 
of investigations would give us data of the most valuable character. 
Experiments conducted for the purpose of determining the effect of continued 
inbreeding ought to throw light upon the supposed bad influences following this 
practice as well as the desirable results. However strongly we may hold to the 
belief that diminished size, lessened fecundity, and weakened constitution follow this 
practice, it is generally conceded that in-and-in breeding does result in giving to the 
animal a greater prepotency. 
We are likewise generally agreed that certain results are almost sure to follow the 
cross breeding of well-established types, and one of the results which is most widely 
accepted is that it destroys the prepotency of animals, and in certain cases this seems 
to be a result, but recent investigations have suggested that certain dominant char- 
acters may be transmitted from parent to offspring unchanged, and this is especially 
true of types which are markedly different. 
We are in the habit of thinking of the whole subject of the relative influence of 
parents upon offspring as a superstition unverified by accurate observation. Lead- 
ing biologists are perhaps a unit in the belief that there can be no influence exerted 
by an animal due to sex alone. When certain characters have apparently been 
transmitted by the male and others by the female, it is generally held that the 
strength of transmission in such cases is determined by a greater prepotency as a 
result of better breeding. Authorities seem to be agreed that there can be no such 
thing as prepotency depending upon sex. At the same time there are a large class 
of facts and some accurate observations that indicate in the case of reciprocal crosses 
there is a decided difference between the qualities of the offspring. It is, per- 
haps, not unreasonable to suppose that by natural selection the male may have 
acquired prepotency in connection with other characters. In nature, among gre- 
garious animals, the strongest male always survives. The increase, therefore, is 
