The review discusses Julian S. Huxley's book "Problems of Relative Growth," which explores the concept of heterogonic growth, where an organ grows at a different rate from the body as a whole. Huxley uses the formula \( y = bx^k \) to describe this relationship, where \( y \) is the size of an organ, \( x \) is the size of the body, and \( k \) represents the relative growth rate. The review highlights Huxley's focus on the mathematical aspects of growth, particularly in deer antlers and invertebrates, but notes that he often overlooks the contributions of earlier pioneers like Ostwald and Brailsford Robertson, who viewed growth as an autocatalytic physico-chemical reaction. The review also criticizes Huxley for neglecting the interrelation of growth and behavior patterns and the physiological aspects of growth. Despite these criticisms, the book is praised for its detailed analysis of growth gradients and its contribution to the comparative aspects of growth, particularly in the context of evolution. The book is well-illustrated and serves as a valuable resource for understanding variation and differential growth.The review discusses Julian S. Huxley's book "Problems of Relative Growth," which explores the concept of heterogonic growth, where an organ grows at a different rate from the body as a whole. Huxley uses the formula \( y = bx^k \) to describe this relationship, where \( y \) is the size of an organ, \( x \) is the size of the body, and \( k \) represents the relative growth rate. The review highlights Huxley's focus on the mathematical aspects of growth, particularly in deer antlers and invertebrates, but notes that he often overlooks the contributions of earlier pioneers like Ostwald and Brailsford Robertson, who viewed growth as an autocatalytic physico-chemical reaction. The review also criticizes Huxley for neglecting the interrelation of growth and behavior patterns and the physiological aspects of growth. Despite these criticisms, the book is praised for its detailed analysis of growth gradients and its contribution to the comparative aspects of growth, particularly in the context of evolution. The book is well-illustrated and serves as a valuable resource for understanding variation and differential growth.