Rabl, Metatneriwi of the Vertebrate Head. 149 



elements of the nucleus and suggestive resemblances be- 

 tween memory and heredity. For the present it is per- 

 haps quite as satisfactory to admit that a physical apparatus 

 for memory remains to be discovered. 



METAMERISM OF THE VERTEBRATE HEAD. 



[ Collated for this Journal.] 



The following notes are, for the most part, derived from 

 the report presented by Professor Rabl and others at the sixth 

 annual meeting of the German Anatomical Association held in 

 Vienna, June, 1892. Passing over the vertebral theory of the 

 skull which, from the time of its founding by Goethe and Oken 

 and its amplification by Owen, flourished uninteruptedly up to 

 1886, we find a modern point of view maintained by Huxley, 

 who showed that no part of the bony skull can be regarded as 

 a modification of primitive vertebrae. Huxley called attention 

 to the fact that all organs of the head must be considered in 

 seeking the genesis of the latter. Especially significant are the 

 nerves and their derivatives, particularly their relations to the 

 gill clefts. The olfactory and optic nerves are not included 

 among cranial nerves proper but are diverticles of the brain. 

 The first gill cleft is innervated by the glossopharyngeal, while 

 those following are supplied by vagus branches. From the 

 trigeminus is derived a superior maxillary and inferior maxillary 

 division which are related to the mouth as the preceeding are to 

 the gill clefts. The trabs and palatal process of the maxillary 

 were regarded as pre-oral visceral arches. Huxley, therefore, 

 still clung to a belief in a definite segmentation of the head. 



Gegenbaur in 1871-72 came to analogous conclusions from 

 his study of Hexanthus. He states that the cranium is com- 

 parable to a portion of the spinal column which has at least as 



