76 THE RIDDLE OF THE UNIVEESE. 



all organic forms, and a firm conviction of a common 

 natural origin. In his famed Metamorphosis oj 

 Plants (1790) he derived all the different species of 

 plants from one primitive type, and all their different 

 organs from one primitive organ — the leaf. In his 

 vertebral theory of the skull he endeavoured to prove 

 that the skulls of the vertebrates — including man — 

 were all alike made up of certain groups of bones, 

 arranged in a definite structure, and that these bones 

 are nothing else than transformed vertebras. It was 

 his penetrating study of comparative osteology that 

 led Goethe to a firm conviction of the unity of the 

 animal organization ; he had recognized that the 

 human skeleton is framed on the same fundamental 

 type as that of all other vertebrates — " built on a 

 primitive plan that only deviates more or less to one 

 side or other in its very constant features, and still 

 developes and refashions itself daily." This re- 

 modelling, or transformation, is brought about, 

 according to Goethe, ±>y the constant interaction of 

 two powerful constructive forces — a centripetal force 

 within the organism, the " tendency to specification," 

 and a centrifugal force without, the tendency to 

 variation, or the " idea of metamorphosis"; the former 

 corresponds to what we now call hereditjr, the latter to 

 the modern idea of adaptation. How deeply Goethe 

 had penetrated into their character by these philo- 

 sophic studies of the " construction and reconstruction 

 of organic natures," and how far, therefore, he must 

 be considered the most important precursor of Darwin 

 and Lamarck, may be gathered from the interesting 

 passages from his works which I have collected in the 

 fourth chapter of my Natural History of Creation. 

 These evolutionary ideas of Goethe, however, like 



