J. B. S. Haldane
Currently, only one work of Haldane's is on-line: Dædalus, or, Science and the Future, a
brief book written in 1924, sketching a vision of the future with remarkable
influence on subsequent thought, and even more remarkable accuracy.
His later book, The Causes of Evolution (1932), while not
on-line, does have at least one on-line review and summary.