66 8. Discourses, Biological and Geological. 66 9. Evolution and Ethics, and Other Essays. 12mo. Cloth, $1.25 per volume. The Crayfish: An Introduction to the Study of Zoology. Manual of the Anatomy of Vertebrated Manual of the Anatomy of Invertebrated Animals. Illustrated. 12mo. Cloth, $2.50. Physiography: An Introduction to the Study of Nature. With New York: D. APPLETON & CO., 72 Fifth Avenue. PREFACE "FOR close upon forty years I have been writing with one purpose; from time to time, I have fought for that which seemed to me the truth, perhaps still more, against that which I have thought error; and, in this way, I have reached, indeed overstepped, the threshold of old age. There, every earnest man has to listen to the voice within: 'Give an account of thy stewardship, for thou mayest be no longer steward.' “That I have been an unjust steward my conscience does not bear witness. At times blundering, at times negligent, Heaven knows: but, on the whole, I have done that which I felt able and called upon to do; and I have done it without looking to the right or to the left; seeking no man's favor, fearing no man's disfavor. "But what is it that I have been doing? In the end one's conceptions should form a whole, though only parts may have found utterance, as occasion arose; now do these exhibit harmony and mutual connexion? In one's zeal much of the old gets broken to pieces; but has one made ready something new, fit to be set in the place of the old? "That they merely destroy without reconstructing, is the especial charge, with which those who work in this direction are constantly reproached. In a certain sense I do not defend myself against the charge; but I deny that any reproach is deserved. "I have never proposed to myself to begin outward construction; because I do not believe that the time has come for it. Our present business is with inward preparation, |