William Bateson (1861-1926) began his academic career working on variation in animals in the light of evolutionary theory. He was inspired by the rediscovery in 1900 of the 1860s work on plant hybridisation by the Austrian monk Gregor Mendel (included here as an appendix) to pursue further experimental work in what he named 'genetics'. He realised that Mendel's results could help to solve difficult biological questions and controversies and to challenge the status quo in evolutionary studies. Annoyed by the 'apathetic' stance of his evolutionist colleagues, and incensed by a scathing critique of Mendel by the Oxford professor Raphael Weldon, Bateson incorporated an English translation of Mendel's work into this 1902 book along with a defence of Mendel's statistical experiments and the principles of heredity derived from them. His book is an impassioned appeal for scientists to adopt this 'brilliant method' which he felt could revolutionise both scholarship and industry.