Book excerpt: Before crude oil and the combustion engine, the industrialized world relied on a different kind of power - the power of the horse. Horses in Society is the story of horse production in the United States, Britain, and Canada at the height of the species' usefulness, the late nineteenth and early twentieth-century. Margaret E. Derry shows how horse breeding practices used during this period to heighten the value of the animals in the marketplace incorporated a intriguing cross section of influences, including Mendelism, eugenics, and Darwinism. Derry elucidates the increasingly complex horse world by looking at the international trade in army horses, the regulations put in place by different countries to enforce better horse breeding, and general aspects of the dynamics of the horse market. Because it is a story of how certain groups attempted to control the market for horses, by protecting their breeding activities or 'patenting' their work, Horses in Society provides valuable background information to the rapidly developing present-day problem of biological ownership. Derry's fascinating study is also a story of the evolution of animal medicine and humanitarian movements, and of international relations, particularly between Canada and the United States.