THE MECHANISTIC MOVEMENT 43 



mechanical theories of secretion and absorp 

 tion ; Liebig, though himself a vitalist, put 

 forward purely chemical theories of various 

 physiological processes; Mayer pointed out 

 the source of the energy of animal move 

 ment ; and last of all came the publication 

 of Darwin's Origin of Species. 



Vitalism itself was also vigorously and 

 directly attacked, and its utter weakness 

 pointed out. Perhaps no more clear and 

 convincing demonstration of the untenability 

 of the vitalistic position has ever been given 

 than in du Bois Reymond's introduction to 

 his Untersuchungen uber thierische Elektricitat 

 published in 1848. 



The momentum of the intellectual move 

 ment of that time has lasted to the present 

 day, and the influence of this movement has 

 spread in ever-widening circles. But we are 

 not concerned with this, nor with the fate of 

 vitalism, but with the further progress of the 

 experimental verification of the mechanistic 

 theory. From this standpoint all that can be 

 said is that the mechanistic theory has, on the 

 whole, fared very badly. Schwann's simple 

 mechanical theory of growth was based on 



