400 THE HISTORY OF BIOLOGY 



and the innermost to the intestinal tube — all observations that have been 

 confirmed by modern research. In his later years Remak paid special atten- 

 tion to the study of electrotherapy, making in this sphere a valuable con- 

 tribution, which, however, does not belong to the history of biology. 



Rudolf Albert Kolliker was born in 1817 at Zurich, the son of a 

 wealthy merchant. He studied zoology in his native town under the aged 

 Oken and afterwards went to Berlin, where, under the guidance of Miiller 

 and Henle, he was initiated into their method of research. When Henle went 

 to Zurich, Kolliker became his prosector, but in 1847 he was invited to 

 become professor at Wiirzburg. There he gave lectures up to 1901, when he 

 resigned; he died three years later. He remained a Swiss subject all through 

 his life. He was one of the foremost teachers of his age; many of the most 

 eminent biologists of the succeeding generation belonged to his school. 



Kolliker's research activities lasted as long as his educational career. 

 He was active far into his ninth decade and was successful to the end; his 

 later work therefore belongs to the following epoch. As a research-worker 

 he was above all a microscopist; the connecting link in his work was formed 

 by the microscopical method, which he employed in a great number of fields 

 of research, everywhere with immense success, although no discovery or idea 

 of supreme importance attaches to his name. He gave a splendid summary of 

 contemporary knowledge on this subject in his Handbuch der Geivebelehre des 

 Menschen, published in the year i85z, which deserves to be called the first 

 modern histology. Its purely external form has been repeated, with the nec- 

 essary modifications required by the progress of science, in innumerable 

 text-books on this subject. Kolliker here expounds with impartiality and 

 far-sightedness the contemporary cell and tissue doctrine; he does not, indeed, 

 entirely deny free cell-formation, but he limits its existence as much as pos- 

 sible. The cells themselves he considers to be constructed of elemental parts : 

 granular and vesicular formations, to which he ascribes a certain degree of 

 independence in growth and development — an idea which was later adopted 

 by many others. He strongly insists upon the importance of the role played 

 by the nucleus in the life of the cell, in its multiplication by division and its 

 other vital manifestations. We must pass over his classification of tissues; 

 he did not adopt Reichert's connective-substance category, but otherwise his 

 classification is clear and concise and his elucidation of the structure and 

 vital manifestations of the different tissues is full of original observations 

 and excellent in its form. Kolliker produced another splendid text-book in 

 his Entwicklungsgeschichte des Menschen und der hoheren Tiere (1861), a summary 

 in clear and comprehensive form of the embryological knowledge of the time. 



Kolliker s investigations 

 Of Kolliker's numerous original investigations it is possible to quote here 

 only a few of the most important, in so far as they come within the period 



