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                    YALE UNIVERSITY

        MRS. HEPSA ELY SILLIMAN MEMORIAL LECTURES


                  PROBLEMS OF GENETICS

              SILLIMAN MEMORIAL LECTURES
          PUBLISHED BY YALE UNIVERSITY PRESS

  ELECTRICITY AND MATTER. _By_ JOSEPH JOHN THOMSON,
    D.SC., LL.D., PH.D., F.R.S., _Fellow of Trinity College,
    Cambridge, Cavendish Professor of Experimental Physics, Cambridge_.
  _Price $1.25 net; postage 10 cents extra._

  THE INTEGRATIVE ACTION OF THE NERVOUS SYSTEM.
    _By_ CHARLES S. SHERRINGTON,
     D.SC., M.D., HON. LL.D., TOR., F.R.S.,
    _Holt Professor of Physiology in the University of Liverpool_.
  _Price $3.50 net; postage 25 cents extra._

  RADIOACTIVE TRANSFORMATIONS. _By_ ERNEST RUTHERFORD,
    D.SC., LL.D., F.R.S., _Macdonald Professor of Physics,
    McGill University_.
  _Price $3.50 net; postage 22 cents extra._

  EXPERIMENTAL AND THEORETICAL APPLICATIONS OF
      THERMODYNAMICS TO CHEMISTRY.
  _By_ DR. WALTHER NERNST, _Professor and Director of the
    Institute of Physical Chemistry in the University of Berlin_.
  _Price $1.25 net; postage 10 cents extra._

  THE PROBLEMS OF GENETICS. _By_ WILLIAM BATESON, M.A.,
    F.R.S., _Director of the John Innes Horticultural Institution,
    Merton Park, Surrey, England_.
  _Price $4.00 net; postage 25 cents extra._

  STELLAR MOTIONS.
    WITH SPECIAL REFERENCE TO MOTIONS DETERMINED BY MEANS OF
    THE SPECTROGRAPH. _By_ WILLIAM WALLACE CAMPBELL, SC.D., LL.D.,
   _Director of the Lick Observatory, University of California_.
  _Price $4.00 net; postage 30 cents extra._

  THEORIES OF SOLUTIONS. _By_ SVANTE AUGUST ARRHENIUS,
    PH.D., SC.D., M.D., _Director of the Physico-Chemical
    Department of the Nobel Institute, Stockholm, Sweden_.
  _Price $2.25 net; postage 15 cents extra._

  IRRITABILITY.
       A PHYSIOLOGICAL ANALYSIS OF THE GENERAL EFFECT OF
       STIMULI IN LIVING SUBSTANCES.
    _By_ MAX VERWORN,
    _Professor at Bonn Physiological Institute_.
  _Price $3.50 net; postage 20 cents extra._

  THE EVOLUTION OF MODERN MEDICINE.
    _By_ SIR WILLIAM OSLER, BART., M.D., LL.D., SC.D.,
    _Regius Professor of Medicine, Oxford University_.
  _Price $3.00 net; postage 40 cents extra._




                     PROBLEMS OF GENETICS

                              BY
                 WILLIAM BATESON, M.A., F.R.S.

        DIRECTOR OF THE JOHN INNES HORTICULTURAL INSTITUTION,
            HON. FELLOW OF ST. JOHN'S COLLEGE, CAMBRIDGE,
        AND FORMERLY PROFESSOR OF BIOLOGY IN THE UNIVERSITY

                     _WITH ILLUSTRATIONS_

                         [Illustration]

                NEW HAVEN: YALE UNIVERSITY PRESS
                    LONDON: HUMPHREY MILFORD
                     OXFORD UNIVERSITY PRESS

                             MCMXIII


                         Copyright, 1913
                       By YALE UNIVERSITY

                First printed August, 1913, 1000 copies


[** Transcriber's Note:
     Underscores "_" before and after a word or phrase indicate ITALICS
       in the original text.
     Hyphenation was used inconsistently by the author and has been
        left as in the original text. ]




                    THE SILLIMAN FOUNDATION

In the year 1883 a legacy of about eighty-five thousand dollars was left
to the President and Fellows of Yale College in the city of New Haven,
to be held in trust, as a gift from her children, in memory of their
beloved and honored mother, Mrs. Hepsa Ely Silliman.

On this foundation Yale College was requested and directed to establish
an annual course of lectures designed to illustrate the presence and
providence, the wisdom and goodness of God, as manifested in the natural
and moral world. These were to be designated as the Mrs. Hepsa Ely
Silliman Memorial Lectures. It was the belief of the testator that any
orderly presentation of the facts of nature or history contributed
to the end of this foundation more effectively than any attempt to
emphasize the elements of doctrine or of creed; and he therefore
provided that lectures on dogmatic or polemical theology should be
excluded from the scope of this foundation, and that the subjects should
be selected rather from the domains of natural science and history,
giving special prominence to astronomy, chemistry, geology, and anatomy.

It was further directed that each annual course should be made the basis
of a volume to form part of a series constituting a memorial to Mrs.
Silliman. The memorial fund came into the possession of the Corporation
of Yale University in the year 1901; and the present volume constitutes
the fifth of the series of memorial lectures.




                           PREFACE

This book gives the substance of a series of lectures delivered in Yale
University, where