46 GENERAL PHYSIOLOGY 



% 



sensations and ideas, that the external world is for us a book with 

 seven seals, and that the only things immediately accessible to 

 our observation and knowledge are the conditions and events of 

 our own consciousness. 



" This simple truth is the greatest and deepest that the human 

 mind has ever conceived. And it leads us also to a complete 

 understanding of that which constitutes the essence of vitalism. 

 The essence of vitalism does not consist in our being satisfied 

 with a word and foregoing the thought. It consists in our taking 

 the only right path of knowledge, proceeding from the known, the 

 inner world, to explain the unknown, the outer world. Mechanism, 

 which is nothing but materialism, takes the reverse and wrong 

 path, it proceeds from the unknown, the outer world, to explain the 

 known, the inner world." 



We have seen that if we would explain the phenomena of the 

 world in their entirety we must go back to elements that are very 

 different from atoms ; that, however, when we confine ourselves to 

 physical phenomena, we find no difference between the factors 

 that work in lifeless and those that work in living bodies. 

 Logic demands that every body, whether living or lifeless, must 

 be subject to the general laws of bodies, which physics and 

 chemistry reveal. It is evident that these two sciences are not 

 yet completed, and that in the future many of their essential 

 views will undergo profound changes. But so much is certain : 

 an explanatory principle can never hold good in physiology with 

 reference to the physical phenomena of life that is not also applicable 

 in chemistry and physics to lifeless nature. The assumption of a 

 specific vital force in every form is not only wholly superfluous, but 

 inadmissible. 



D. CELL-PHYSIOLOGY 



How does it happen that after the ill-reputed idea of the 

 existence of a vital force has been regarded for decades as definitely 

 set aside, modern science turns again to this outlawed word as a 

 motto, in spite of the great variety of its significations ? Why 

 have such words as " vital force " and " vitalism " been able to 

 exert in recent times an influence upon investigators such as 

 Hanstein ('80), Kerner ('87), Bunge ('94), Rindfleisch ('88, '95), 

 and others ? It is not difficult to discover the reason. It is the 

 same that in Haller's time gave birth to the idea of vital force, 

 namely, the inability to explain vital phenomena mechanically, i.e., 

 to reduce them to chemico-physical principles. This condition 

 has existed during recent decades also, but it was largely 

 neglected so long as the attention was occupied more with the 

 epoch-making physiological discoveries of Ludwig, du Bois- 

 Reymond, Helmholtz and others. We are becoming more con- 



