Bristol Mercury.—"The authors ... handle a subject which has an obvious controversial side with strength, and there are convincing qualities as well as lucidity in the views so admirably set forth."
Times.—"The two authors ... deal suggestively with the difficulties of natural selection ... and their arguments are supported by a goodly array of facts."
Liverpool Courier.—"Contains a great deal of well-marshalled observation."
Lancet.—"A very interesting book ... simply and clearly written."
Dundee Advertiser.—"... a book which is at the same time one of the most interesting and readable on the controversial aspects of natural history published in recent years."
The Christian World.—"This very interesting work."
Bristol Times.—"A work of value, which will give occasion to many to think, and an admirable presentation of facts."
Westminster Review.—"... written in popular language and contains many original observations."
Daily Chronicle.—"An interesting and suggestive book."