The Variation of Animals and Plants under Domestication, vol 2 | Page 5

AND EUROPEAN
TREES--GALLS--EFFECTS OF PARASITIC
FUNGI--CONSIDERATIONS OPPOSED TO THE BELIEF IN THE
POTENT INFLUENCE OF CHANGED EXTERNAL
CONDITIONS--PARALLEL SERIES OF VARIETIES--AMOUNT
OF VARIATION DOES NOT CORRESPOND WITH THE DEGREE
OF CHANGE IN THE
CONDITIONS--BUD-VARIATION--MONSTROSITIES
PRODUCED BY UNNATURAL TREATMENT--SUMMARY.

CHAPTER 2.
XXIV.--LAWS OF VARIATION--USE AND DISUSE, ETC.
NISUS FORMATIVUS, OR THE CO-ORDINATING POWER OF
THE ORGANISATION--ON THE EFFECTS OF THE INCREASED
USE AND DISUSE OF ORGANS--CHANGED HABITS OF LIFE--
ACCLIMATISATION WITH ANIMALS AND PLANTS--VARIOUS
METHODS BY WHICH THIS CAN BE EFFECTED--ARRESTS OF
DEVELOPMENT--RUDIMENTARY ORGANS.
CHAPTER 2.
XXV.--LAWS OF VARIATION, continued.--CORRELATED
VARIABILITY.
EXPLANATION OF TERM CORRELATION--CONNECTED WITH
DEVELOPMENT--MODIFICATIONS CORRELATED WITH THE
INCREASED OR DECREASED SIZE OF PARTS--CORRELATED
VARIATION OF HOMOLOGOUS PARTS--FEATHERED FEET IN
BIRDS ASSUMING THE STRUCTURE OF THE
WINGS--CORRELATION BETWEEN THE HEAD AND THE
EXTREMITIES--BETWEEN THE SKIN AND DERMAL
APPENDAGES--BETWEEN THE ORGANS OF SIGHT AND
HEARING--CORRELATED MODIFICATIONS IN THE ORGANS
OF PLANTS--CORRELATED MONSTROSITIES--CORRELATION
BETWEEN THE SKULL AND EARS--SKULL AND CREST OF
FEATHERS--SKULL AND HORNS-- CORRELATION OF
GROWTH COMPLICATED BY THE ACCUMULATED EFFECTS
OF NATURAL SELECTION--COLOUR AS CORRELATED WITH
CONSTITUTIONAL PECULIARITIES.
CHAPTER 2.
XXVI.--LAWS OF VARIATION, continued.--SUMMARY.
THE FUSION OF HOMOLOGOUS PARTS--THE VARIABILITY

OF MULTIPLE AND HOMOLOGOUS PARTS--COMPENSATION
OF GROWTH--MECHANICAL PRESSURE--RELATIVE
POSITION OF FLOWERS WITH RESPECT TO THE AXIS, AND
OF SEEDS IN THE OVARY, AS INDUCING
VARIATION--ANALOGOUS OR PARALLEL
VARIETIES--SUMMARY OF THE THREE LAST
CHAPTERS.

CHAPTER 2.
XXVII.--PROVISIONAL HYPOTHESIS OF PANGENESIS.
PRELIMINARY REMARKS. FIRST PART:--THE FACTS TO BE
CONNECTED UNDER A SINGLE POINT OF VIEW, NAMELY,
THE VARIOUS KINDS OF REPRODUCTION--REGROWTH OF
AMPUTATED PARTS--GRAFT-HYBRIDS --THE DIRECT
ACTION OF THE MALE ELEMENT ON THE
FEMALE--DEVELOPMENT--THE FUNCTIONAL
INDEPENDENCE OF THE UNITS OF THE
BODY--VARIABILITY--INHERITANCE-- REVERSION. SECOND
PART:--STATEMENT OF THE HYPOTHESIS--HOW FAR THE
NECESSARY ASSUMPTIONS ARE
IMPROBABLE--EXPLANATION BY AID OF THE HYPOTHESIS
OF THE SEVERAL CLASSES OF FACTS SPECIFIED IN THE
FIRST PART--CONCLUSION.
CHAPTER 2.
XXVIII.--CONCLUDING REMARKS.
DOMESTICATION--NATURE AND CAUSES OF
VARIABILITY--SELECTION--DIVERGENCE AND
DISTINCTNESS OF CHARACTER--EXTINCTION OF
RACES--CIRCUMSTANCES FAVOURABLE TO SELECTION BY

MAN--ANTIQUITY OF CERTAIN RACES--THE QUESTION
WHETHER EACH PARTICULAR VARIATION HAS BEEN
SPECIALLY PREORDAINED.
INDEX.

THE VARIATION OF ANIMALS AND PLANTS UNDER
DOMESTICATION.
VOLUME II.
CHAPTER 2.
XIII.
INHERITANCE continued--REVERSION OR ATAVISM.
DIFFERENT FORMS OF REVERSION. IN PURE OR UNCROSSED
BREEDS, AS IN PIGEONS, FOWLS, HORNLESS CATTLE AND
SHEEP, IN CULTIVATED PLANTS. REVERSION IN FERAL
ANIMALS AND PLANTS. REVERSION IN CROSSED VARIETIES
AND SPECIES. REVERSION THROUGH BUD-PROPAGATION,
AND BY SEGMENTS IN THE SAME FLOWER OR FRUIT. IN
DIFFERENT PARTS OF THE BODY IN THE SAME ANIMAL. THE
ACT OF CROSSING A DIRECT CAUSE OF REVERSION,
VARIOUS CASES OF, WITH INSTINCTS. OTHER PROXIMATE
CAUSES OF REVERSION. LATENT CHARACTERS.
SECONDARY SEXUAL CHARACTERS. UNEQUAL
DEVELOPMENT OF THE TWO SIDES OF THE BODY.
APPEARANCE WITH ADVANCING AGE OF CHARACTERS
DERIVED FROM A CROSS. THE GERM, WITH ALL ITS LATENT
CHARACTERS, A WONDERFUL OBJECT. MONSTROSITIES.
PELORIC FLOWERS DUE IN SOME CASES TO REVERSION.
The great principle of inheritance to be discussed in this chapter has
been recognised by agriculturists and authors of various nations, as

shown by the scientific term ATAVISM, derived from atavus, an
ancestor; by the English terms of REVERSION, or
THROWING-BACK; by the French PAS-EN-ARRIERE; and by the
German RUCKSCHLAG, or RUCKSCHRITT. When the child
resembles either grandparent more closely than its immediate parents,
our attention is not much arrested, though in truth the fact is highly
remarkable; but when the child resembles some remote ancestor or
some distant member in a collateral line,--and in the last case we must
attribute this to the descent of all the members from a common
progenitor,--we feel a just degree of astonishment. When one parent
alone displays some newly-acquired and generally inheritable character,
and the offspring do not inherit it, the cause may lie in the other parent
having the power of prepotent transmission. But when both parents are
similarly characterised, and the child does not, whatever the cause may
be, inherit the character in question, but resembles its grandparents, we
have one of the simplest cases of reversion. We continually see another
and even more simple case of atavism, though not generally included
under this head, namely, when the son more closely resembles his
maternal than his paternal grand-sire in some male attribute, as in any
peculiarity in the beard of man, the horns of the bull, the hackles or
comb of the cock, or, as in certain diseases necessarily confined to the
male sex; for as the mother cannot possess or exhibit such male
attributes, the child must inherit them, through her blood, from his
maternal grandsire.
The cases of reversion may be divided into two main classes which,
however, in some instances, blend into one another; namely, first, those
occurring in a variety or race which has not been crossed, but has lost
by variation some character that it formerly possessed, and which
afterwards reappears. The second class includes all cases in which an
individual with some distinguishable character, a race, or species, has at
some former