We follow the cycle of his reflection beginning with "adaptation" as the great mystery to be solved; in the middle and sanguine period of life, "adaptation" is regarded as fully explained by natural selection; in the closing and conservative period of life "adaptation" is again regarded in some of its phases as entirely beyond human powers of interpretation, not only in the evolution of the mental and spiritual nature of man, but in such marvelous manifestations as the scales of butterflies or the wings of birds.
From our own intellectual experience we may sympathize with the rebound of maturity from the buoyant confidence of the young man of thirty-five who finds in natural selection the entire solution of the problem of fitness which has vexed the mind and aroused the scientific curiosity of man since the time of Empedocles. We have ourselves experienced a loss of confidence with advancing years, an increasing humility in the face of transformations which become more and more mysterious the more we study them, although we may not join with this master in his appeal to an organizing and directing supernatural principle. Younger men than Wallace, both among the zoologists and philosophers of our own time are giving a somewhat similar metaphysical solution of the eternal problem of adaptation, which still baffles and transcends our powers of experiment and of reasoning.
List of Books of Alfred Russel Wallace, O.M., F.R.S., etc.
Sent to the author of the present article in a letter of May 3, 1912.
"In accordance with your request I herewith send you a list of my published books. The delay has been caused by the only complete copy I had having been sent away for publication.
"I have always intended to make out a complete list of my various communications to periodical literature, but have hitherto been unable to find time to do so. All my scientific communications, however, will be found in the Royal Society's Catalogue of Scientific Papers which no doubt you have access to."| 1. | "Palm Trees of the Amazon and their Uses." Pub. 1853. |
| 2. | "A Narrative of Travels on the Amazon and Rio Negro, with an Account of the Native Tribes and Observations on the Climate, Geology and Natural History of the Amazon Valley." Pub. 1853, new edition 1889. |
| 3. | "The Malay Archipelago, the Land of the Orang-utan and the Bird of Paradise. A Narrative of Travel with Studies of Man and Nature." First edition 1869 (2 vols.). Tenth edition 1898 (1 vol.). |
| 4. | "Contributions to the Theory of Natural Selection." Pub. as single vol. 1870. Pub. with "Tropical Nature" in 1 vol. 1891. |
| 5. | "Miracles and Modern Spiritualism." Pub. 1874. Revised edition 1896. |
| 6. | "The Geographical Distribution of Animals, with a Study of the Relation of Living and Extinct Faunas as Elucidating the Past Changes of the Earth's Surface." Pub. 1876 (2 vols.). |
| 7. | "Tropical Nature and Other Essays." Pub. 1 vol. 1878. Pub. with "Natural Selection" in 1 vol. 1891. |
| 8. | "Australasia." Stanford's Compendium of Geography and Travel. Pub. 1879, 3d edition 1883. New edition 1893, 1st vol., "Australia and New Zealand." |
