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

The book reviews historical and contemporary ideas about internal secretions and their role in heredity, arguing that hormones can influence development and the evolution of adaptations. It examines Mendelian heredity, mutations, and chromosomal findings, reports some experimental observations, and assesses how hormones might determine somatic sex characters and non-sexual traits. Comparative examples and reproduced figures illustrate pigment responses, altered forms, and mutations. The author weighs evidence for and against hormone-based explanations, considers interactions between environmental factors and germ plasm, and discusses implications for metamorphosis, recapitulation, and the origin of evolutionary novelties.