Hormones and Heredity

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Hormones and Heredity

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Title: Hormones and Heredity
Author: J. T. Cunningham
Release Date: July, 2005 [EBook #8517] [Yes, we are more than one year ahead of schedule] [This file was first posted on July 18, 2003]
Edition: 10
Language: English
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HORMONES AND HEREDITY
A Discussion Of The Evolution Of Adaptations And The Evolution Of Species
By J. T. CUNNINGHAM, M.A. (OXON), F.Z.S.
Sometime Fellow of University College, Oxford Lecturer in zoology at East London College, University of London
LONDON CONSTABLE AND CO. LTD. 1921

PREFACE
My chief object in writing this volume was to discuss the relations of modern discoveries concerning hormones or internal secretions to the question of the evolution of adaptations, and on the other hand to the results of recent investigations of Mendelian heredity and mutations. I have frequently found, from verbal or written references to my opinions, that the evidence on these questions and my own conclusions from that evidence were either imperfectly known or misunderstood. This is not surprising in view of the fact that hitherto my only publications on the hormone theory have been a paper in a German periodical and a chapter in an elementary text-book. The present publication is by no means a thorough or complete exposition of the subject, it is merely an attempt to state the fundamental facts and conclusions, the importance of which it seems to me are not generally appreciated by biologists.
I have reviewed some of the chief of the recent discoveries concerning mutations, Mendelism, chromosomes, etc., but have not thought it necessary to repeat the illustrations which are contained in many of the volumes to which I have referred. I have made some Mendelian experiments myself, not always with results in agreement with the strict Mendelian doctrine, so that I am not venturing to criticise without experience. I have not hesitated to reprint the figure, published many years ago, of a Flounder showing the production of pigment under the influence of light, because I thought it was desirable that the reader should have before him this figure and those of an example of mutation in the Turbot for comparison when following the argument concerning mutation and recapitulation.
I take this opportunity of expressing my thanks to the Councils of the Royal Society and the Zoological Society for permission to reproduce the figures in the Plates. I also desire to thank Professor Dendy, F.R.S., of King's College for his sympathetic interest in the publication of the book, and Messrs. Constable and Co. for the care they have taken in its production.
J. T. CUNNINGHAM. London, June 1921.

CONTENTS
INTRODUCTION - Historical Survey Of Theories Or Suggestions Of Chemical Influence In Heredity


CHAPTER I
- Classification And Adaptation


CHAPTER II
- Mendelism And The Heredity Of Sex


CHAPTER III
- Influence Of Hormones On Development Of Somatic Sex-Characters


CHAPTER IV
- Origin Of Somatic Sex-Characters In Evolution


CHAPTER V
- Mammalian Sexual Characters, Evidence Opposed To The Hormone Theory


CHAPTER VI
- Origin Of Non-Sexual Characters: The Phenomena Of Mutation


CHAPTER VII
- Metamorphosis and Recapitulation
INDEX
LIST OF PLATES
PLATE I. Recessive Pile Fowls
PLATE II. Abnormal Specimen Of Turbot
PLATE III. Flounder, Showing Pigmentation Of Lower Side After Exposure To Light

INTRODUCTION
Historical Survey Of Theories Or Suggestions Of Chemical Influence In Heredity
Weismann, strongly as he denied the possibility of the transmission of somatic modifications, admitted the possibility or even the fact of the simultaneous modification of soma and germ by external conditions such as temperature. Yves Delage [Footnote: Yves Delage, _L'Hérédité_ (Paris, 1895), pp. 806-812.] in 1895, in discussing this question, pointed out how changes affecting the soma would produce an effect on the ovum (and presumably in a similar way on the sperm). He writes:--
'Ce qui empêche l'oeuf de recevoir la modification reversible c'est qu'étant constitué autrement que les cellules différenciées de l'organisme il est influencé autrement qu'elles par les mêmes causes perturbatrices. Mais est-il impossible que malgré la différence de constitution physico-chimiques il soit influencé de la même fa?on?'
The author's