414 THE HISTORY OF BIOLOGY 



animals and he carried out many valuable investigations in that field. He re- 

 tained his youthful interest in polar research and keenly promoted Sw^edish 

 voyages of polar exploration in his later years. When the theory of the glacial 

 period was first advanced, he embraced it with enthusiasm and produced 

 valuable zoological proofs of it, establishing the existence in some of the 

 deeper inland seas of peculiar animal forms that otherwise belong to the 

 fauna of the polar seas and which have manifestly survived in the lakes 

 since some earlier period when the sea covered the land. These surviving 

 forms Loven named "relicts," and since then Scandinavian research has been 

 occupied in their study. 



The foremost Swedish biologist during this period, however, was un- 

 doubtedly Anders Adolf Retzius (1796-1860). Born at Lund, where his 

 father was a distinguished natural scientist, he studied under him and the 

 anatomist Florman, and later in Copenhagen under Ludvig Jacobson. When 

 still a young man he was appointed professor at the Veterinary Institute 

 in Stockholm and at the same time held a post at the Carolinian Institute, 

 where he at once became the greatest force the Institute had with the excep- 

 tion of Berzelius. This twofold work as a teacher, however, did not prevent 

 him from following up his biological researches both at home and on expedi- 

 tions, in the course of which he came into close contact with many eminent 

 scientists, including J. Miiller, who became a loyal friend, and Purkinje, from 

 whom he learned microscopical technique. He is the pioneer of comparative 

 anatomy in Sweden; he introduced it into the country not merely as a sub- 

 ject for research, but also — after overcoming strong opposition on the part 

 of older authorities — as a subject of medical training. His own works are ex- 

 traordinarily many-sided. A biographer has said of them that they are seldom 

 consistently worked out and that the whole of his research work was marked 

 by a certain restlessness. As a matter of fact, most of his literary production 

 consists of short articles for journals, written simply in the form of notes 

 without any theoretical reasoning or even observations on the earlier his- 

 tory of the problem under discussion. Nevertheless, many of these articles 

 have had a deep influence on the development of biology, owing to the great 

 value of the facts set forth in them, as, for instance, his account of the anat- 

 omy of the Myxinoidei, written in 18x2., in which these animals' vascular 

 and nervous systems, head-cartilage, and various other organs are described 

 — a work which formed the basis of J. Miiller's important monograph on 

 the Myxinoidei — and, further, his study of the connexion between the 

 spinal and the sympathetic nervous system in the horse — one of the first 

 of its kind, and a beautifully illustrated work. Like Purkinje, Retzius in- 

 vestigated the microscopical structure of dental bone, extending this inves- 

 tigation to a number of animal forms. In 1841 he went with J. Miiller to 

 the west coast of Sweden and there applied himself, inter alia, to the study 



