two ambassadors in foreign lands, the means you destine for the engraving and printing will soon be absorbed. You will struggle with domestic difficulties, and at sixty years of age (tremble at the sight of this number!) you will be as uncertain as you are to-day, whether you possess, even in your collection of drawings, all that is to be found among amateurs. How exhaust an ocean in which the species are indefinitely increasing? Finish, first, what you have this December, 1837, and then, if the subject does not weary you, publish the supplements in 1847. You must not forget that these supplements will be of two kinds: 1st. Ideas which modify some of your old views. 2nd. New species. Only the first kind of supplement would be really desirable. Furthermore, you must regain your intellectual independence and not let yourself be scolded any more by M. de Humboldt. Little will it avail you should I vanish from the scene of this world with your fourteenth number! When I am a fossil in my turn I shall still appear to you as a ghost, having under my arm the pages you have failed to interpolate and the volume of that eternal America which I owe to the public. I close with a touch of fun, in order that my letter may seem a little less like preaching. A thousand affectionate remembrances. No more ice, not much of echinoderms, plenty of fish, recall of ambassadors in partibus, and great severity toward the book-sellers, an infernal race, two or three of whom have been killed under me. A. DE HUMBOLDT. I sigh to think of the trouble my horrible writing will give you. A letter of about the same date from Von Buch shows that, however he might storm at Agassiz's heterodox geology, he was in full sympathy with his work in general. LEOPOLD VON BUCH TO LOUIS AGASSIZ. December 22, 1837.