subscribers gave evidence of a cordiality toward his work which surprised as much as it gratified him. On the list there were also some of his old European subscribers to the "Poissons Fossiles," among them the King of Prussia, who still continued, under the influence of Humboldt, to feel an interest in his work. FROM HUMBOLDT TO AGASSIZ. September 1, 1856. . . .I hear that by some untoward circumstances, no doubt accidental, you have never received, my dear Agassiz, the letter expressing the pleasure which I share with all true lovers of science respecting your important undertaking, "Contributions to the Natural History of the United States." You must have been astonished at my silence, remembering, not only the affectionate relations we have held to each other ever since your first sojourn at Paris, but also the admiration I have never ceased to feel for the great and solid works which we owe to your sagacious mind and your incomparable intellectual energy. . .I approve especially the general conceptions which lie at the base of the plan you have traced. I admire the long series of physiological investigations, beginning with the embryology of the so-called simple and lower organisms and ascending by degrees to the more complicated. I admire that ever-renewed comparison of the types belonging to our planet, in its present condition, with those now found only in a fossil state, so abundant in the immense space lying between the shores opposite to northern Europe and northern Asia. The geographical distribution of organic forms in curves of equal density of occupation represents in great degree the inflexions of the isothermal lines. . .I am charged by the king, who knows the value of your older works, and who still feels for you the affectionate regard which he formerly expressed in person, to request that you will place his name at the head of your long list of subscribers. He wishes that an excursion across the Atlantic valley may one day bring you, who have so courageously braved Alpine summits, to the historic hill of Sans Souci. . .