HAECKEL, hek'C'1, Ernst, German zoolo gist: b. Potsdam, 16 Feb. 1834. After the usual gymnasium course, he at first devoted himself to botany at the University of Berlin, but ow ing to his father's wishes took up the study of medicine at Wiirzburg, where he enjoyed the guidance of Virchow and Kolliker. Returning to Berlin in 1854, he took courses with the great physiologist Johannes Muller, who ex erted a lasting influence on him and turned his attention to zoology, and after several addi tional semesters at Wiirzburg, he received the degree of M.D. in Berlin in 1857. After a very brief attempt at practising he defi nitely abandoned this profession for zoology and during a study trip to Messina laid the foundation of his scientific career by an inten sive investigation of radiolaria. In 1861 he obtained permission to lecture at the Univer sity of Jena and was soon appointed assistant professor of zoology. A monograph on the radiolaria published the following year estab lished his professional reputation. It was here that Haeckel first clearly expressed his ad vocacy of Darwinian principles, of which he henceforth became the most and nt defender among German scientists. In the beginning his championship found expression in a two volume work, 'Geuerelle Morphologic der Organismen,' which appeared in 1866 and has kept its place as one of the classics of philo sophical zoology. Owing to the extremely technical character of this chef-d'euvre, its im mediate effect even upon specialists was slight. Two years later, accordingly, Haeckel summed uo the essential elements of evolutionary philosophy in a more popular volume on (Natiirliche Schopfungsgeschichte' (translated into English as 'History of Creation'). A corresponding work dealing specifically with the descent of man appeared in 1874 under the title 'Anthropogenie) (English translation 'Evolu tion of Man'). The frankly antitheological point of view assumed in these writings drew upon Haeckel the anathemas of the Church, while his daring hypotheses as to the develop ment of animal types elicited the vigorous criticism of many sober colleagues and in volved him in bitter controversies, notably with his one-time teacher and friend, Virchow (1877). On the other hand, his powerful per sonality won over new adherents to Darwinism and stimulated a host of young zoologists, of whom some, like Oskar Hertwig and Max Ver worn, have attained world-wide fame. While .Haeckel's popular books were being issued in ever-increasing editions, he continued his con tributions to science by monographs on the medusw, siphonophora, sponges and other low organisms, and elaborated a new monumental work on the radiolaria for the British Chal lenger expedition. These years of strenuous activity were diversified with excursions to Madeira, Egypt, Algeria, Ceylon and other re mote regions. His technical labors ceased with the 'Systematische Phylogenie> (1894-96).
From this time on Haeckel stands forth ex elusively as a leader of intellectual radicalism, seeking converts to his philosophy of “monism,p :which is designed to unify the most general teachings of science and take the place of re ligion in the world-view of modern man. The
manifesto of this creed was published in 1899 under the title of 'Die Weltratsel) (English translation
Among specialists Haeckel's reputation has suffered on account of his obstinacy, which for example led him to cling to the be lief in the inheritance of acquired char acters, and also from his excessive fondness for hypotheses. Nevertheless many of these have proved extremely fertile and promoted the development of modern zoology. Over and above the many special con tributions which science owes him must be reckoned a great number of significant con cepts which he first introduced into biological thinking. He was also an innovator in making experimental investigations in zoology, though he was unable to appreciate the later evolution of experimental methods. His essays in phi losophy cannot be fairly judged from the metaphysician's level but must be understood as the strivings for a unified world-view of an unusually artistic temperament estranged from the traditional creeds. Haeckel's unique posi tion in the history of modern thought lies in the extraordinary effectiveness of his propa ganda as an apostle of intellectual liberalism. For biographical data consult Wilhelm BOlsche, 'Ernst Haeckel) (Leipzig 1900), and the two anniversary volumes 'Was wir Ernst Haeckel Heinrich Schmidt, editor (Leipzig 1914).