OUE LIFE. 47 



the sum of all the movements which we perceive in 

 the living organism. He sought especially to give 

 them the same mechanical interpretation in the life of 

 the senses and of the mind as in the working of the 

 muscles ; the same in the phenomena of circulation, 

 respiration, and digestion, as in generation and develop- 

 ment. Mailer's success was chiefly due to the fact 

 that he always began with the simplest life-phenomena 

 of the lowest animals, and followed them step by step 

 in their gradual development up to the very highest, to 

 man. In this his method of critical comparison proved 

 its value both from the physiological and from the 

 anatomical point of view. Johannes Mailer is, more- 

 over, the only great scientist who has equally cultivated 

 these two branches of research, and combined them 

 with equal brilliancy. Immediately after his death 

 his vast scientific kingdom fell into four distinct 

 provinces, which are now nearly always represented 

 by four or more chairs — human and comparative 

 anatomy, pathological anatomy, physiology, and the 

 history of evolution. This division of Mailer's 

 immense realm of learning in 1858 has been compared 

 to the rending of the empire which Alexander the 

 Great had consolidated and ruled. 



Among the many pupils of Johannes Mailer who, 

 either during his lifetime or after his death, laboured 

 hard for the advancement of the various branches of 

 biology one of the most fortunate — if not the most 

 important — was Theodor Schwann. When the able 

 botanist Schleiden, in 1838, indicated the cell as the 

 common elementary organ of all plants, and proved 

 that all the different tissues of the plant are merely 

 combinations of cells, Johannes Mailer recognised at 

 once the extraordinary possibilities of this important 



