The Hon. and Rev. W. Herbert, afterward Dean of Manchester, in the fourth volume of the Horticultural Transactions , 1822 , and in his work on the Amaryllidaceae ( 1837 , pages 19, 339), declares that “horticultural experiments have established, beyond the possibility of refutation, that botanical species are only a higher and more permanent class of varieties.” He extends the same view to animals. The dean believes that single species of each genus were created in an originally highly plastic condition, and that these have produced, chiefly by inter-crossing, but likewise by variation, all our existing species.