304 THE ORGANISM AS AN HISTORICAL BEING 



They quite ignored the possibility that a different 

 explanation of the facts might be given ; they seized upon 

 the simplest and most obvious solution because it satisfied 

 their overwhelming desire for simplification. But is the 

 simplest explanation always the truest especially when 

 dealing with living things? One may be permitted to doubt 

 it. It is easy to account for the structural resemblance of 

 the members of a classificatory group, by the assumption 

 that they are all descended from a common ancestral form ; 

 it is easy to postulate any number of hypothetical generalised 

 types ; but in the absence of positive evidence, such 

 simplicist explanations must always remain doubtful. The 

 evolutionists, however, had no such scruples. 



Phylogenetic method differed in no way from transcen- 

 dental except perhaps that it had learnt from von Baer 

 and from Darwin to give more weight to embryology. 

 The criticisms passed by Cuvier and von Baer upon the 

 transcendentalists and their recapitulation theory might with 

 equal justice be applied to the phylogenetic speculations 

 which were based on the biogenetic law. There was the 

 same tendency to fix upon isolated points of resemblance 

 and disregard the rest of the organisation. Thus, on the 

 ground of a presumed analogy of certain structures to the 

 vertebrate notochord, several invertebrate groups, as the 

 Enteropneusta, the Rhabdopleura, the Nemertea, were 

 supposed to be, if not ancestral, at least offshoots from the 

 direct line of vertebrate descent. And if other points of 

 resemblance could in some of these cases be discovered, yet 

 no successful attempt was made to show that the total 

 organisation of any of these forms corresponded with that of 

 the Vertebrate type. With the possible exception of the 

 Ascidian theory, all the numerous theories of vertebrate 

 descent suffered from this irremediable defect, and none 

 carried complete conviction. 



In spite of the efforts of the evolutionists, as of those 

 of the transcendentalists, the phyla or "types" remained 

 distinct, or at best connected by the most general of 

 bonds. 



The close affinity of transcendentalists and evolutionists 

 is shown very clearly in their common contrast in habits of 



