It may be added here as an evidence of Agassiz's faith in the institutions of the United States and in her intellectual progress that he was himself naturalized in the darkest hour of the war, when the final disruption of the country was confidently prophesied by her enemies. By formally becoming a citizen of the United States he desired to attest his personal confidence in the stability of her Constitution and the justice of her cause. Some light is thrown upon the work and incidents of these years by the following letters:-- FROM SIR PHILIP DE GREY EGERTON. LONDON, ALBEMARLE ST., April 16, 1861. MON CHER AGASS,* (* An affectionate abbreviation which Sir Philip often used for him.) I have this morning received your handsome and welcome present of the third volume of your great undertaking, and this reminds me how remiss I have been in not writing to you sooner. In fact, I have had nothing worth writing about, and I know your time is too valuable to be intrenched upon by letters of mere gossip. I have not of course had time to peruse any portion of the monograph, but I have turned over the pages and seen quite enough to sharpen my appetite for the glorious scientific feast you have so liberally provided. And now that the weight is off your mind, I hope shortly to hear that you are about to fulfill this year the promise you made of returning to England for a good long visit, only postponed by circumstances you could not have foreseen. Now that you have your son as the sharer of your labors, you will be able to leave him in charge during your absence, and so divest your mind of all care and anxiety with reference to matters over the water. Here we are all fighting most furiously about Celts and flint implements, struggle for life, natural selection, the age of the world, races of men, biblical dates, apes, and gorillas, etc., and the last duel has been between Owen and Huxley on the anatomical distinction of the pithecoid brain compared with that of man. Theological controversy has also been rife, stirred up by the "Essays and Reviews," of which you have no doubt heard much. For myself, I have been busy preparing, in conjunction with Huxley, another decade of fossil fishes, all from the old red of Scotland. . .Enniskillen is quite well. He is now at Lyme Regis. . . At about this time the Copley Medal was awarded to Agassiz, a distinction which was the subject of cordial congratulation from his English friends. FROM SIR RODERICK MURCHISON. BELGRAVE SQUARE, March, 1862. MY DEAR AGASSIZ,