26 THE RIDDLE OF THE UNIVERSE. 



studies. The numerous comparative-anatomical works 

 of Gegenbaur are, like his well-known Manual of 

 Human Anatomy, equally distinguished by a thorough 

 empirical acquaintance with their immense multitudes 

 of facts, and by a comprehensive control of his 

 material, and its philosophic appreciation in the 

 evolutionary sense. His recent Comparative Anatomy 

 of the Vertebrata establishes the solid foundation on 

 which our conviction of the vertebral character of 

 man in every aspect is chiefly based. 



Microscopic anatomy has been developed, in the 

 course of the present century, in a very different 

 fashion from comparative anatomy. At the beginning 

 of the century (1802) a French physician, Bichat, 

 made an attempt to dissect the organs of the human 

 body into their finer constituents by the aid of the 

 microscope, and to show the connection of these 

 various tissues (hista, or tela). This first attempt led 

 to little result, because the scientist was ignorant of 

 the one common element of all the different tissues. 

 This was first discovered (1838) in the shape of the 

 cell, in the plant- world, by Matthias Schleiden, and 

 immediately afterwards proved to be the same in the 

 animal world by Theodore Schwann, the pupil and 

 assistant of Johannes Muller at Berlin. Two other 

 distinguished pupils of this great master, who are still 

 living, Albert Kolliker and Rudolph Virchow, took up 

 the cellular theory, and the theory of tissues which is 

 founded on it, in the 'sixties, and applied them to the 

 human organism in all its details, both in health and 

 disease ; they proved that, in man and all other 

 animals, every tissue is made up of the same micro- 

 scopic particles, the cells, and these " elementary 

 organisms" are the real, self-active citizens which, in 



