138 THE THEORY OF EVOLUTION 



plants to one fundamental form is ' extremely unlikely ' 

 to be correct, as all investigators, so long as they are 

 ' exact/ will willingly allow. 



It would be well if in every evolutional hypothesis 

 these suggested limitations were adhered to. There 

 still remains a wide field for research, and especially 

 the question whether and how the types were established 

 within their limits, and what they were before they 

 appeared as completed types which would be preserved 

 for us and perhaps could alone be preserved. Should, 

 for instance, the Ferns represent a true type, yet that 

 is not to say a priori that the plants which we call 

 Ferns were always so constituted. One thing alone 

 seems fairly certain. ' Ferns ' are and were always 

 different from Equisetums, or ' Invertebrates ' show no 

 genetic connection with Vertebrates, or Vertebrates 

 were never such Invertebrates as we know them. 1 



i Reinke agrees with this quite emphatically. In his book, Die Welt 

 ah Tat, p. 351, he says : ' It is of the greatest significance that in the multi- 

 formity of forms almost unlimited types appear. These types embrace the 

 enormous number of the now living plants and animals and those which 

 have reached us as fossils.' On p. 352 he continues : ' I quote here a palseon- 

 tological fact, which is of the greatest importance for the theory of descent. 

 While we find in the petrifactions of the Palaeozoic and Mesozoic periods 

 not only other species, but also a preponderance of other genera than at 

 present, yet according to the evidence of the remains found there has 

 never been discovered, even in the oldest periods, any other main type of 

 animal or plant than what we have in the present age. Genera and species 

 have become extinct and been replaced by others. Yet the fundamental 

 types have survived from the time of the oldest formations to the present 

 day.' The acceptance of a polyphyletic evolution i.e. of varied developed 

 series, separated from the commencement becomes more and more the 

 dominant opinion. 0. Hertwig, Reinke, Kerner v. Marilaun, Steinmann, 

 Zittel, Deperet, Koken, Wasmann, and others regard this as the only 

 admissible view or at least as the most probably correct one, 



