130 THE THUOBY OF EVOLUTION 



arisen through the development and evolution of one 

 original form. 



The possibility that Ferns, Equisetse, and Club- 

 mosses might be traced back to a common starting- 

 point cannot be a priori disproved. 



But one circumstance must be expressly emphasized. 

 The differences which exist between the classes and the 

 families of animals and plants are the first in the organic 

 kingdom which may be bridged over by evolution : 

 the question whether and how the associated forms 

 now in existence can be regarded as the results of 

 developmental (evolutionary) process is the first 

 problem of an evolutional hypothesis. The evolution 

 must not here, in this question, be regarded as in any 

 way put forward as a fact : that would be quite 

 inadmissible. 



No one has so far maintained that, on closer study 

 of the relations between the inorganic and organisms, 

 or between animals and plants, positive starting-points 

 for the acceptance of an evolution have been found. 

 Spontaneous generation is put forward by investigators 

 exclusively as a postulate, as we have seen ; the trans- 

 formation of a plant into an animal is little discussed, 

 and it is simply impossible to explain it by ' evolution/ 



Consequently the testing of the connection of the 

 greater systematic groups among themselves is of 

 fundamental importance for the evolution question, 

 since here for the first time a genetic connection is 

 not from the outset excluded. 



From the results of the systematic classification 



