4/6 NOTES. 



entoderm, tbis most simply explains the progressive development 

 of this distinction, which may be traced through the series of 

 Worms, and up to Vertebrates. 



96 (i. 320). Palingenetic and Kenogenetic germination. In 

 the germ-history of Vertebrates no clear conception of the 

 embryological process has yet been attained, because all authors 

 have started from the higher Vertebrates (usually from the 

 Chick) and have assumed that the form of evolution occurring 

 in this case is original and typical. It is only since the germ- 

 history of the Amphioxus has taught us the palingenetic, really 

 orio'inal form of germination of Vertebrate organisms, that we 

 have been enabled, by Comparative Ontogeny (and especially by 

 the principles of the Gastraea theory), rightly to understand and 

 to explain phylogenetically the kenogenetic forms of germination 

 of higher Vertebrates. 



97 (i. 321). The Diagrams in Plates IV. and V. are as simple 

 and abstract as possible, in order to render the desired general 

 explanation as easy as possible. 



98 (i. 346). Primitive Vertebrae and Metamera. For the 

 right conception of " primitive vertebral '' structure it is espe- 

 cially necessary to point out that the primitive vertebrae are 

 much more than their name indicates. They must, in fact, be 

 conceived as individual, consecutive sections of the trunk, 

 which have arisen one after the other, as true "metamera," or 

 consecutive pieces (" Generelle Morphologie," vol. i. p. 312). 

 Each primitive vertebra of a Vertebrate, like each trunk-segment 

 or metameron of an Annelid or Arthropod, contains all the 

 essential, morphological constituent parts, characteristic of the 

 corresponding animal-tribe. 



99 (i. 34-9). Origin of the Primitive Vertebraa. My concep- 

 tion of these as individual, morphological " consecutive pieces," 

 which, like the metamera of Cestods and Annelids, have arisen 

 by terminal budding from a single unarticulated piece, has been 

 much attacked. I therefore emphatically remark that I only 

 understand this process in the widest sense. In both cases there 

 is certainly a reproduction of individual, like parts, which have 

 originated (in time and space) consecutively. 



