Book contents
- Frontmatter
- Contents
- Foreword by Stephen Jay Gould
- Introduction by JOHN TYLER BONNER
- Addendum
- TYPOGRAPHICAL NOTE
- I Introductory
- II On Magnitude
- III The Forms of Cells
- IV The Forms of Tissues, or Cell-aggregates
- V On Spicules and Spicular Skeletons
- VI The Equiangular Spiral
- VII The Shapes of Horns and of Teeth or Tusks
- VIII On Form and Mechanical Efficiency
- IX On the Theory of Transformations, or the Comparison of Related Forms
- X Epilogue
- Index
- Seven Clues to the Origin of Life
V - On Spicules and Spicular Skeletons
Published online by Cambridge University Press: 05 February 2014
- Frontmatter
- Contents
- Foreword by Stephen Jay Gould
- Introduction by JOHN TYLER BONNER
- Addendum
- TYPOGRAPHICAL NOTE
- I Introductory
- II On Magnitude
- III The Forms of Cells
- IV The Forms of Tissues, or Cell-aggregates
- V On Spicules and Spicular Skeletons
- VI The Equiangular Spiral
- VII The Shapes of Horns and of Teeth or Tusks
- VIII On Form and Mechanical Efficiency
- IX On the Theory of Transformations, or the Comparison of Related Forms
- X Epilogue
- Index
- Seven Clues to the Origin of Life
Summary
In this chapter and the following ones D'Arcy Thompson is struggling against the notion that all form can simply be explained by heredity, and that therefore changes in form inevitably map out phylogenetic relations. Instead he repeatedly suggests that physical forces (such as those which produce the variations of shapes of snow-flakes) are of prime importance and relationships of shape may not justify any family tree or a sequence in time, but simply show mathematical kinship. Today we are inclined to combine the two and say that the genes, the units of heredity, do control shapes, but that the activities of genes are constrained by the physicochemical properties of the chemical substances and the configuration of these substances present in the organism. This does not touch upon the question of whether or not all the shapes produced are adaptively significant. D'Arcy Thompson's strong arguments that they are not is a reaction against those who see a selective advantage to all structures. But this issue cannot be resolved without an ecological study of each example, a Gargantuan task that is unlikely ever to be achieved. All we can say at the moment is that there is no a priori reason why some structures, which have been initiated by mutation and formed within the confines of physicochemical laws, should not utterly lack any adaptive significance, and yet remain fixed in the population.
- Type
- Chapter
- Information
- On Growth and Form , pp. 132 - 171Publisher: Cambridge University PressPrint publication year: 1992