Hormones and Heredity / A Discussion of the Evolution of Adaptations and the Evolution of Species

by J. T. Cunningham

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 façon?'