As a general statement the foregoing could not be improved. But the invitation to prepare this article contained a suggestion of particularity with which it is possible for me to comply.[Footnote: Not only have I preserved all the letters from Agassiz, the first dated Sept. 4, 1866, and the last Nov. 25, 1873, but also my diaries in which are recorded all significant incidents and conversations from my first introduction in 1856 to the last interview, Sept. 5, 1873. [Note by Professor Wilder.]] The courses given by Agassiz on zoology and geology were attended by me during the three years (1859-62) of my pupilage with Jeffries Wyman, and the two years (1866-68) in which I was the assistant of Agassiz himself. Naturally, and also for special reasons, the deepest impression was made by the first and the last of these courses. With the former the charm of novelty intensified the great, indeed indescribable, charm of the speaker. No topic was to me so important as the general problem of animal life, and no expositor could compare with Agassiz. As an outlet for my enthusiasm each discourse was repeated, to the best of my ability, for the benefit of my companion, James Herbert Morse, '63, on the daily four-mile walk between Cambridge and our Brookline home. So sure was I that all the statements of Agassiz were correct and all his conclusions sound, that any doubts or criticisms upon the part of my acute and unprejudiced friend shocked me as a reprehensible compound of heresy and lese-majesty.