This review discusses Julian S. Huxley's 1932 book, "Problems of Relative Growth," which explores the concept of heterogonic growth, where parts of an organism grow at different rates than the whole. Huxley uses the formula y = bx^k to describe this phenomenon, where k represents the relative growth rate of an organ compared to the rest of the body. The book examines how k varies across different organisms, from bacteria to humans. While Huxley's mathematical approach is praised for its clarity and depth, the reviewer notes that he occasionally overlooks important contributions from other scientists, such as Ostwald and Brailsford Robertson, and fails to integrate physiological and behavioral perspectives. The book also discusses the relationship between growth and behavior, highlighting differences in metabolic responses and skeletal development among various animals. Huxley's analysis of regenerating limbs and the effects of starvation and aging on growth gradients is particularly insightful. However, the reviewer criticizes Huxley's limited exploration of biochemical aspects, such as the role of glutathione in growth potential. The final chapter discusses the broader implications of heterogonic growth for other areas of biology, offering new insights into evolutionary processes. The book is well-illustrated and serves as a valuable introduction to the study of variation and differential growth. It is considered a worthy addition to the literature on growth, following in the footsteps of other notable authors.This review discusses Julian S. Huxley's 1932 book, "Problems of Relative Growth," which explores the concept of heterogonic growth, where parts of an organism grow at different rates than the whole. Huxley uses the formula y = bx^k to describe this phenomenon, where k represents the relative growth rate of an organ compared to the rest of the body. The book examines how k varies across different organisms, from bacteria to humans. While Huxley's mathematical approach is praised for its clarity and depth, the reviewer notes that he occasionally overlooks important contributions from other scientists, such as Ostwald and Brailsford Robertson, and fails to integrate physiological and behavioral perspectives. The book also discusses the relationship between growth and behavior, highlighting differences in metabolic responses and skeletal development among various animals. Huxley's analysis of regenerating limbs and the effects of starvation and aging on growth gradients is particularly insightful. However, the reviewer criticizes Huxley's limited exploration of biochemical aspects, such as the role of glutathione in growth potential. The final chapter discusses the broader implications of heterogonic growth for other areas of biology, offering new insights into evolutionary processes. The book is well-illustrated and serves as a valuable introduction to the study of variation and differential growth. It is considered a worthy addition to the literature on growth, following in the footsteps of other notable authors.