But to return to the distribution of his time in these busy days. Having passed, as we have seen, the greater part of the day in the Museum and the school, he had the hours of the night for writing, and rarely left his desk before one or two o'clock in the morning, or even later. His last two volumes of the "Contributions," upon the Acalephs, were completed during these years. In the mean time, the war between North and South had broken out, and no American cared more than he for the preservation of the Union and the institutions it represented. He felt that the task of those who served letters and science was to hold together the intellectual aims and resources of the country during this struggle for national existence, to fortify the strongholds of learning, abating nothing of their efficiency, but keeping their armories bright against the return of peace, when the better weapons of civilization should again be in force. Toward this end he worked with renewed ardor, and while his friends urged him to suspend operations at the Museum and husband his resources until the storm should have passed over, he, on the contrary, stimulated its progress by every means in his power. Occasionally he was assisted by the Legislature, and early in this period an additional grant of ten thousand dollars was made to the Museum. With this grant was begun the series of illustrated publications already mentioned, known as the "Bulletin of the Museum of Comparative Zoology in Cambridge." During this period he urged also the foundation of a National Academy of Sciences, and was active in furthering its organization and incorporation (1863) by Congress. With respect to this effort, and to those he was at the same time making for the Museum, he was wont to recall the history of the University of Berlin. In an appeal to the people in behalf of the intellectual institutions of the United States during the early years of the war he says: "A well known fact in the history of Germany has shown that the moment of political danger may be that in which the firmest foundations for the intellectual strength of a country may be laid. When in 1806, after the battle of Jena, the Prussian monarchy had been crushed and the king was despairing even of the existence of his realm, he planned the foundation of the University of Berlin, by the advice of Fichte, the philosopher. It was inaugurated the very year that the despondent monarch returned to his capital. Since that time it has been the greatest glory of the Prussian crown, and has made Berlin the intellectual centre of Germany."