Louis John Rudolph Agassiz, an American naturalist, of French descent, born in Motiers, canton of Fribourg, Switzerland, on the lake of Morat, May 28, 1807. His family was among the Huguenots who were driven from France by the revocation of the edict of Nantes, and took refuge in the Pays de Vaud. For six generations the lineal ancestors of Agassiz have been clergymen. His father was pastor of St. Imier, a Protestant parish in the ancient bishopric of Basel, and removed to Motiers on account of the severity of the climate at the former place; his mother was Mlle. Rose Mayor, the daughter of a physician in the canton of Vaud. She superintended the education of her son Louis until he reached the age of 11, when he was sent to the gymnasium of Bienne, a small town in the canton of Bern. In the mean time his father had removed from Motiers to the little town of Orbe, at the foot of the Jura. Here, during the vacations, the student's attention was drawn to the natural sciences, under the influence of a young clergyman named Fivaz. His studies were first directed to plants. Having studied four years at Bienne, Louis entered the college of Lausanne, where he passed two years, and then went to Zurich in 1824, where he remained two years in the medical school.

He continued his medical studies at the university of Heidelberg, devoting himself chiefly to anatomy and physiology under Tiedemann, zoology under Leuck-art, and botany under Bischoff. In the autumn of 1827 he entered the university of Munich, which had recently been reorganized. Among the eminent men assembled there Agassiz formed intimate friendships. He studied the organization of plants and their geographical distribution with Martins; he lived in the house of Dollinger, with whom he studied the embryonic development of animals; he was in- timate with Wagler; with Oken he discussed the. principles of classification; with Fuchs he studied mineralogy; and for four successive years he attended all the lectures of Schelling on philosophy. He was the leading spirit in a; select circle of young men who met to discuss scientific subjects. This society was called the ! little academy, and so interesting were the lee- tures and discussions that the professors were glad to take part in them. When Dom Pedro of Brazil married an Austrian princess, the Austrian and Bavarian governments seized the opportunity of sending to that country a scientific exploring expedition.

The naturalists of the expedition were Martins, Spix, Natterer, and Pohl. Agassiz, still a student, had already published a few special papers. On the return of the scientific corps, Martins occupied himself with the publication of his great work on Brazil. The zoological portion was intrusted to Spix, but he had not completed it at the time of his death. Martius immediately selected young Agassiz to elaborate the ichthyological department, upon which very little had been done, and the manner in which he accomplished the task placed him at once in the foremost rank of naturalists. These studies and labors divert- ! ed him from the profession of medicine, to which he had been destined by his parents, The allowance he had hitherto received from his father, on which, moderate as it was, he had not only subsisted, but had employed a distinguished young artist, Dinkel, was now withdrawn. Agassiz then applied to Cotta, the publisher, who, struck by the value of the materials Agassiz had collected for a "Natural History of the Fresh-water Fishes of Europe," I and no doubt impressed with the genius of the young naturalist, enabled him by a timely sup- ply of funds to complete the work. This was his second great undertaking.

Meantime he presented himself as a candidate for the degree of doctor of philosophy, which he took at Er-langen, after passing a very severe examination with distinction. In the same year he took at Munich the degree of doctor of medicine, on which occasion he maintained the superiority of woman in a Latin dissertation upon the thesis, Femina humana superior mari. The great work on the fresh-water fishes was ad- vancing. After the double examination for degrees, Agassiz visited Vienna, where he prosecuted his studies in the museum, and devoted himself especially to the study of the fishes of the Danube. In that city he became acquainted with the leading naturalists, and particularly Fitzinger, While studying living fishes, his attention was drawn to the fossil species found in the fresh-water deposits of Oeningen and Glarus in Switzerland, and of Solenhofen in Bavaria. Immediately after the completion of the work on the fishes of Brazil, he commenced his researches upon the fossil fishes, and devoted seven years to the study before beginning the publication.

This was continued through ten years, and was brought to a close in 1844. In the course of his preparation for this work, Agassiz visited the principal museums of Europe, accompanied by a skilful artist; and so great was the interest felt universally in these researches, and the confidence which the author inspired, that he was allowed to take with him for examination and comparison the most valuable specimens of more than 80 public and private museums, some of which he was permitted to retain from five to ten years. He was enabled to visit Paris and to prosecute his researches in the collections of that capital, by a most disinterested act on the part of a clergyman and friend of his father, Mr. Chris-tinat, who at a later period visited Agassiz in America, and passed some years in his house. This gentleman had just come into possession of a small sum of money, which he offered in aid of his young friend's pursuits. Agassiz at once became acquainted with Humboldt, who was then residing in Paris, and with Cuvier, the eminent naturalist, who had just commenced his work on fishes.

The drawings of Agassiz so delighted Cuvier, that he offered to relinquish to the young man all the materials he had himself collected; and from that time to his death he cherished a warm friendship for the Swiss naturalist, and received him in his family on the most intimate terms. In his investigations of the fresh-water fishes, the rivers and lakes of Europe were thoroughly explored by Agassiz, in order to compare those of the different water basins, especially the Rhine, the Rhone, and the Danube, with their tributaries. These investigations had mostly been made while he was still a student in Heidelberg and Munich, during the vacations, when he travelled on foot over the whole of southern Germany and Switzerland. Some time after the death of Cuvier, 1882, Agassiz returned to Switzerland, on the invitation of citizens of Neufchatel, where preparations were making to reorganize the college. He received the appointment of professor of natural history in that establishment, and began preparations for the publication of the work on which he had been occupied so long. He also extended his researches to other departments of zoology.