AGASSIZ, Jean Louis Rudolphe, naturalist, born in Motier, canton Fribourg, Switzerland, 28 May 1807; died in Cambridge, Massachusetts, 14 December 1873. His father was pastor of the Protestant parish of Motier, a profession that his forefathers had for six generations; his mother, Mlle. Rose Mayor, was the daughter of a physician residing in Cudrefin, canton de Vaud. His mother, who was a woman of high endowments and rare culture, directed his first studies at home. At the age of ten years he and his younger brother were sent to the gymnasium at Biel, in the neighboring canton of Bern; here he acquired the ancient and modern languages, which later became so valuable to him in his biological investigations. Very early in life Agassiz showed a fondness for natural science, and in his boyhood days he began collecting specimens. His leisure time at the gymnasium was similarly occupied, and his first collection of fishes dates from this period. During the vacations spent at Orbe (Fribourg), whither his father had been transferred, he became intimate with a young clergyman named Fivaz, who encouraged his interest in natural history and led him to the active study of botany. He continued his education in the College at Lausanne in 1823, and in 1824 began the study of medicine in Zurich, in accordance with the earnest wishes of his parents. Thence he went to Heidelberg, where he devoted his principal attention to anatomy under the famous 'l:mcle-mann, and in 1827 to Munich, where he came under the influence of Schelling, Oken, Martius, Dollinger, Wagler, Zuccarini, Fuchs, and yon Kobell. Dollinger, especially, at whose house he occupied a room, recognized the high talent of his pupil, and fostered his long-cherished plan of devoting himself exclusively to zoology. While at Munich, Agassiz organized the club called the "Little Academy," and became its presiding officer. It was before this society that Born, Rudolphi, Michaelis, Schimper, and Braun first disclosed their latest discoveries, and even Dollinger made his new ideas known there before they were published. Martius, then lately returned from Brazil, where he had been sent on a scientific exploring expedition, entrusted young Agassiz, on the death of Spix, with the description of the fishes that had been collected. This work, completed when he had scarcely reached his twenty-first year, was dedicated to Cuvier, and published in Latin (Munich, 1829). The brilliant accomplishment of so arduous an undertaking at once gained him a reputation as one of the first ichthyologists. His attention was then directed to fossil fishes, and those at the museum in Munich, as well as such other paleontological collections as were available in central Germany, were carefully studied.

Meanwhile he had not, neglected his medical studies, and in 1829 he received the doctor's degree in medicine from Munich, and in philosophy from Erlangen in 1830. His second great undertaking was the "Natural History of the Fresh-water Fishes of Europe," in the preparation of which he was assisted pecuniarily by the publisher, Cotta, of Stuttgart. It was never completed, but was partially published in 1839-'40. After receiving his degrees, he spent some time in Vienna, attending the hospitals, and pursuing his studies of the fossil fishes by examining the collections in the imperial museum. By the liberality of his uncle, Francois Mayor, and of Christinat, a friend of Agassiz's father, he was enabled to continue his studies, and spent two years (1831-'2) in Paris. This city was then the great scientific centre of Europe, and its collections were the richest and most celebrated on the continent. Men who were eminent as specialists were attracted to the capital, and formed part of the brilliant circle under the leadership of the distinguished Humboldt. Cuvier, the great French naturalist, received the young Agassiz with enthusiasm. The valuable treasures of the Paris museum were at his service, and the material collected for years by Cuvier for his work on fishes was freely transferred to the young naturalist. The development theory of Geoffroy, then recently advanced, was opposed by Cuvier with all the power of his science and detailed knowledge. Agassiz accepted the ideas of his master, and firmly adhered to them throughout his life, and in later years, when the development theory advanced by Darwin came into prominence, he was uncomproraising in his efforts against its promulgation. Humboldt also became his firm friend and patron, aiding him materially in the publication of his work. Among his associates were Owen, Milne-Edwards, Rud. Wagner, and Johannes Muller.

In 1832, shortly after the death of Cuvier, he returned to Switzerland and became professor of natural history in the College at Neuchatel. His labors on the fossil fishes were gradually approaching completion, the first of the five quarto volumes, "Recherches sur les poissons fossiles," appearing in 1833 and the last in 1843. This was undoubtedly Agassiz's most important contribution to science, and forms, with Cuvier's, Valenciennes', and Johannes Miiller's works, the foundation of our present knowledge of fishes. In this book one thousand species were completely, and seven hundred partially, figured and described. At Neufchatel he gathered around him young and talented pupils, and the little city became one of the chief seats of science in Switzerland. He created the natural history museum, and was the chief founder of the scientific society, which issued the first volume of its memoirs in 1835. During the summers frequent scientific excursions were made in the Jura and the Alps. These expeditions led to his study of the glaciers, and in 1840 he published his first Etudes sur les glaciers," which gave the results of his observations during the eight preceding summers. He had erected a station on the middle of the Aar glacier at a height of 8,000 feet above the sea and twelve miles from any human habitation, and from this now celebrated Hotel des Neufchgtelois he conducted his experiments. In 1847 he published his "Systome glaciaire," in which he thoroughly discussed the chief phenomena of glaciers and more fully developed his views on their earlier extension. In the mean while he had also devoted considerable attention to the echinoderms, and in 1836 and 1837 published special memoirs on them. His monograph on living and fossil echinoderms, published in parts, was first issued in 1839; portions of this work were prepared by Desor and by Valentin. In 1834, in 1835, and in 1840, Agassiz visited England to obtain material for his work on fossil fishes, and as a result he published monographs on the " Fossil Fishes of the Devonian System " (1844), and on the " Fishes of the London'Clay " (1845).

In 1846 he came to the United States, partly to make himself familiar with the geology and natural history of this country, in fulfilment of a mission suggested to the king of Prussia by Humboldt, and partly to deliver a series of lectures on " Comparative Embryology," at the Lowell institute, Boston. The lectures met with a most cordial reception, and by special request he delivered an additional course on glacial phenomena. He then visited New York, Philadelphia, Charleston, and other cities, in search of material for his report. In 1847 Supt. A. died Bache placed at his disposal the use of the steamer "Bibb," belonging to the coast survey. This led to a scientific cruise along the coast of Massachusetts, and some years later (1850-'1)to a more extended trip to the coral reefs of Florida. In this manner he became thoroughly familiar with the marine life along our shores. The liberality of this offer affording him such valuable facilities for the continuation of his studies, and the enthusiasm with which he was everywhere greeted, induced him to make the United States his home. The Prussian government released him from his scientific mission, and he accepted, in 1848, the chair of zoology and geology in the Lawrence scientific school at Cambridge, Massachusetts, a professorship specially created for him by Mr. Lawrence. At Cambridge, as abroad, he attracted brilliant young men, enthusiasts in science, many of whom today are among the leading naturalists in this country[ Of these, besides his son Alexander, may be mentioned Bickmore, Clark, Hartt, Hyatt, Lyman, Morse, Niles, Packard, Putnam, Scudder, Shaler, Stimpson, Tenney, Verrill, Wilder, and Ward. He prepared during 1848, with Dr. A. A. Gould, " Principles of Zoo1ogy," a textbook for the use of schools and Colleges. In the summer of the same year, with twelve of his pupils, he made an exploring expedition to Lake Superior, and the results were published in a volume entitled " Lake Superior; its Physical Characteristics," etc. (1850).

In succeeding years he traversed the entire country, lecturing in all the larger cities and accumulating vast collections of specimens, which constituted the foundation of the natural history museum in Cambridge. From 1851 to 1854 he was professor of comparative anatomy and zoology in the medical College in Charleston, South Carolina, and during this time he studied the marine animals of the southern coast, also visiting the adjoining states; but, as the climate did not agree with him, he returned to Cambridge. In 1854 he brought to a successful termination, by the publication of fourth volume, the "Bibliographic Zoologim et Geologim," which he had begun in 1848 with H. E. Strickland. This work contains a full list of all the periodicals devoted to zoology and geology, and an alphabetical list of authors and their works in the same departments. It was the complement of his "Nomenclator Zoo1ogicus," which appeared in 1842-'46. Agassiz next began to collect material for the publication of a magnificent work to be called "Contributions to the Natural History of the United States." In 1857 the first volume appeared, containing as an introduction his well-known "Essay on Classification," in which the question of development was considered in a manner directly in opposition to the now generally accepted theory of descent. Of this work, projected on a gigantic scale, only four volumes ever appeared during his life; his son issued the fifth, left incomplete. His attention was then turned to his collections, which had accumulated in great bulk, and, unclassified, were stored wherever available accommodation could be obtained. In June 1859, the museum of comparative zoo1ogy was founded, with Agassiz as its curator, and until his death much of his time was devoted to the classification and arrangement of the specimens.

In 1865, his health having become somewhat impaired by constant work, he was enabled, by the liberality of Mr. Nathaniel Thayer, a Boston merchant, to visit Brazil. Here again he made great collections, which now enrich the museum at Cambridge, and a journal of his trip was published in 1867. He was appointed in 1868 a non-resident professor of natural history in Cornell University, Ithaca, New York, and there delivered a course of lectures. In 1871, the coast survey, having occasion to send the new war steamer "Hassler" around Cape Horn to operate on the Pacific coast, extended to Agassiz an invitation to make the voyage in the interest of science. The expedition, with a competent corps of assistants, sailed in December and reached San Francisco late in August. Much valuable scientific information was accumulated, new facts concerning the glacial phenomena of South America were obtained, careful observations of the temperature of the water and deep-sea soundings were regularly made, and great collections of fishes, reptiles, mollusks, and other specimens of natural history were gathered, a large portion of which were added to his museum in Cambridge. The gift of Penikese Island and money for its endowment, by John Anderson, of New York, in 1873, made possible the establishment of the Penikese island school of natural history. This summer school, affording opportunities for the study of specimens direct from nature without the intervention of textbooks, was the accomplishment of a long-cherished project of Agassiz's. The first season was enthusiastically passed, and at its end the pupils bade farewell to the master, who, a few months later, after a short illness, died in Cambridge. His grave in Mr. Auburn is marked by a boulder from the glacier of the Aar, and shaded by pine trees brought from Switzerland.

Agassiz received the degree of LL.D. from the universities of Edinburgh and Dublin before he was thirty years of age. In 1836 he was elected to the French academy of sciences, and in the same year he was made a fellow of the royal society of London. He was also a member of nearly all the learned and scientific societies in Europe. In the United States, he was a member of the American association for the advancement of science, of the American academy of arts and sciences, of the Boston natural history society, and of many other scientific organizations. He was also an original member of the national academy of sciences.

In addition to the works already enumerated, there appeared, under the title of "The Structure of Animal Life" (Boston, 1852), a collection of newspaper extracts of lectures delivered extemporaneously. This book was never revised by him, and contains numerous errors. Agassiz also published "Methods of Study in Natural History" (Boston, 1863); "Geological Studies" (two series, Boston, 1866-'76; and "Journal in Brazil" (Boston, 1868), in conjunction with Mrs. Elizabeth Cary Agassiz, who has edited "Louis Agassiz: His Life and Correspondence" (Boston, 1886). His contributions of scientific memoirs to transactions and proceedings of various societies were numerous. A complete list of them may be found in the catalogue of scientific papers published by the royal society of London.