DOMAIN OF EVOLUTIONARY HYPOTHESIS 117 



become an animal, the whole nature of its principle 

 must be transformed, and only when this transforma- 

 tion is complete can consciousness show itself for the 

 first time. A thing ' a/ however, which can only become 

 a thing c b ' by a total alteration of its whole being, abso- 

 lutely excludes all connection with ' b ' by gradual evolu- 

 tion ; because though evolution may effect development 

 of a basis or the improvement of a completed object if 

 the necessary evolutional tendency leads thereto, it 

 cannot effect new and higher modes of existence. 

 Animals and plants cannot therefore be brought into 

 genetic connection ; the question of the origin of the 

 animals from plants forms no problem of tbe hypothesis 

 of evolution. 



3. We are not justified, in the present state of our 

 knowledge, in bringing the families and classes of the 

 animal and plant worlds into genetic connection. 



(1) Introductory remarks, on the systematic treatment 

 of animals and plants. 



The systematic division of the animal kingdom 

 has, since Cuvier, been effected mainly according to 

 two points of view 1 according to their affinity to a 

 definite type (form of construction), and according to 

 the height of their organization. The type arises 

 from the mutual relative positions of the organs in the 

 organism and the symmetry of the whole ; the height 



1 See, e.g., B. R. Hertwig : Lehrbuch der Zoologie, Jena, 1910, p. 104. 



