PREFACE TO THE THIED EDITION. XXIX 



rejects the ancestral series as I have arranged it. He 

 says : " We have been able to prove the assertion that Men 

 and Apes must have originated from a common line ; — more 

 than this we have never asserted, and further back than 

 this it is absolutely impossible to prove anything or even 

 to show with any degree of probability more than that, 

 at farthest, the higher Mammals may perhaps have de- 

 veloped from Pouched Animals {Marswpialia)" Against 

 this view of Yogt's, I assert, that with the same logical 

 " certainty or probability " the common descent of all 

 Mammals from lower Vertebrates, primarily from Am- 

 phibia, less immediately from Fishes, may be f * proved." 

 With the same " certainty or probability " — I assert again 

 — the descent of all these Skulled Animals (Craniota) from 

 Skull-less forms (Acrania, allies of Amphioxus), the descent 

 of these latter from Chorda Animals (Chordoma, forms 

 allied to Ascidia), and the descent of these Chorda Animals 

 from low Worms, " may be proved." With the same 

 "certainty or probability" — I say finally — "we have been 

 able to prove the assertion," that these Worms must, 

 in their turn, have originated from a Gastraea (resembling 

 the gastrula), and these Gastraeads from a one-celled 

 organism (resembling the undifferentiated Amoeba). Proofs, 

 as I believe, of these assertions are given in Chapters 

 XIIL-XXV. of this edition. 



The whole of this hypothetic pedigree Karl Vogt entirely 

 rejects, without, however, substituting another He espe- 

 cially denies our relationship with the Selachii and the 

 Amphioxus, with the Ascidia and the Gastraea, although the 

 especially great phylogenetic significance of these instruc- 

 tive animal-forms is almost unanimously recognized by the 



