THE EVOLUTION OF LIFE 



mechanical course was interrupted from time to time by 

 the supernatural creation of organisms is opposed to 

 pure reason, the unity of nature, and the law of substance. 

 We must, therefore, hold fast above all to the conviction 

 that all biogenetic processes are just as reducible to the 

 mechanics of substance as all other natural phenomena. 



The mechanical and natural character of the develop- 

 ment of inorganic nature, the earth and the whole 

 material world, was established mathematically at the 

 end of the eighteenth century by the great atheist 

 Laplace in his Micanique Celeste (1799). The similar 

 cosmogony which Kant had expounded in 1755 in his 

 General Natural History and Theory of the Heavens only 

 obtained recognition at a later date {Riddle, chapter xiii.). 

 But the possibility of giving a mechanical explanation of 

 organic nature was not seen until Darwin provided a 

 solid foundation for the theory of descent by his theory 

 of selection in 1859. I made the first comprehensive 

 attempt to do this in 1866 in my General Morphology, the 

 aim of which is expressed in the title: "General out- 

 lines of the science of organic forms, mechanically 

 grounded on Darwin's improvement of the theory of 

 descent." Especially in the second volume of the work, 

 the "General Evolution of Organisms," I endeavored 

 to show that both sections of the science, ontogeny (or 

 embryology) and phylogeny, can be reduced to physio- 

 logical activities of the plasm, and so explained mechani- 

 cally, in the wider meaning of the word. 



When I stated the nature and the aim of phylogeny in 

 1866, most biologists regarded my attempt as unjusti- 

 fiable, as they did Darwinism itself, of whiqh it was a 

 natural consequence. Even the famous Emil Dubois- 

 Reymond, to whom as a physiologist it should have 

 been welcome, described it as "a poor romance"; he 

 compared my first attempts to construct the genealogical 

 tree of the organic classes, on the evidence of paleontol- 



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