extension of the field of zoology. I had no idea of its direct connection with geology, or of its bearing on the problem of the successive introduction of animals on the earth. I had never thought of the larger and more philosophical view of nature as one great world, but considered the study of animals only as it was taught by descriptive zoology in those days. At about this time, however, I made the acquaintance of two young botanists, Braun and Schimper, both of whom have since become distinguished in the annals of science. Botany had in those days received a new impulse from the great conceptions of Goethe. The metamorphosis of plants was the chief study of my friends, and I could not but feel that descriptive zoology had not spoken the last word in our science, and that grand generalizations, such as were opening upon botanists, must be preparing for zoologists also. Intimate contact with German students made me feel that I had neglected my philosophical education; and when, in the year 1827, the new University of Munich opened, with Schelling as professor of philosophy, Oken, Schubert, and Wagler as professors of zoology, Dollinger as professor of anatomy and physiology, Martius and Zuccarini as professors of botany, Fuchs and Kobell as professors of mineralogy, I determined to go there with my two friends and drink new draughts of knowledge. During the years I passed at Munich I devoted myself almost exclusively to the different branches of natural science, neglecting more and more my medical studies, because I began to feel an increasing confidence that I could fight my way in the world as a naturalist, and that I was therefore justified in following my strong bent in that direction. My experience in Munich was very varied. With Dollinger I learned to value accuracy of observation. As I was living in his house, he gave me personal instruction in the use of the microscope, and showed me his own methods of embryological investigation. He had already been the teacher of Karl Ernst von Baer; and though the pupil outran the master, and has become the pride of the scientific world, it is but just to remember that he owed to him his first initiation into the processes of embryological research. Dollinger was a careful, minute, persevering observer, as well as a deep thinker; but he was as indolent with his pen as he was industrious with his brain. He gave his intellectual capital to his pupils without stint or reserve, and nothing delighted him more than to sit down for a quiet talk on scientific matters with a few students, or to take a ramble with them into the fields outside the city, and explain to them as he walked the result of any recent investigation he had made. If he found himself understood by his listeners he was satisfied, and cared for no farther publication of his researches. I could enumerate many works of masters in our science, which had no other foundation at the outset than these inspiriting conversations. No one has borne warmer testimony to the influence Dollinger has had in this indirect way on the progress of our science than the investigator I have already mentioned as his greatest pupil,--von Baer. In the introduction to his work on embryology he gratefully acknowledges his debt to his old teacher.