I am happy to see that you publish the whole together. The parceling out of such a work would have led to endless delays; but, for mercy's sake, take care of your eyes; they are OURS. I have not neglected the subscriptions in Russia, but I have, as yet, no answer. At a venture, I have placed the name of M. von Buch on my list. He is absent; it is said that he will go to Greece this summer. Pray make it a rule not to give away copies of your work. If you follow that inclination you will be pecuniarily ruined. I wish I could have been present at your course of lectures. What you tell me of them delights me, though I am ready to do battle with you about those metamorphoses of our globe which have even slipped into your title. I see by your letter that you cling to the idea of internal vital processes of the earth, that you regard the successive formations as different phases of life, the rocks as products of metamorphosis. I think this symbolical language should be employed with great reserve, I know that point of view of the old "Naturphilosophie;" I have examined it without prejudice, but nothing seems to me more dissimilar than the vital action of the metamorphosis of a plant in order to form the calyx or the flower, and the successive formation of beds of conglomerate. There is order, it is true, in the superposed beds, sometimes an alternation of the same substance, an interior cause,--sometimes even a successive development, starting from a central heat; but can the term "life" be applied to this kind of movement? Limestone does not generate sandstone. I do not know that there exists what physiologists call a vital force, different from, or opposed to, the physical forces which we recognize in all matter; I think the vital process is only a particular mode of action, of limitation of those physical forces; action, the nature of which we have not yet fully sounded. I believe there are nervous storms (electric) like those which set fire to the atmosphere, but that special action which we call organic, in which every part becomes cause or effect, seems to me distinct from the changes which our planet has undergone. I pause here, for I feel that I must annoy you, and I care for you too much to run that risk. Moreover, a superior man like yourself, my dear friend, floats above material things and leaves a margin for philosophic doubt. Farewell; count on the little of life that remains to me, and on my affectionate devotion. At twenty-six years of age, and possessed of so much knowledge, you are only entering upon life, while I am preparing to depart; leaving this world far different from what I hoped it would be in my youth. I will not forget the Bichir and the Lepidosteus. Remember always that your letters give me the greatest pleasure. . .