uu 



Wliai Fkouikp onnld sliow witli regard to tlic N. liypoglossiis i8 

 likewise of iiiiporlaiice. He foniid nairielv in llie course of' lliis 

 cerebral nerve, always conceived as purely motorical, spinalganglions, 

 and so it was obvious that tins nerve wonld be nothing else than 

 the complex of the nerves belonging to the spinal cranium-region. 



This view of Froriep's concerning the spinal character of the 

 occipital regiou of liie cianiiini liuds in reality no longer con- 

 tradiction. From all sides conllrmatioiis of his discoveries have come 

 also with other species of animals. Everywhere it has been possible 

 to indicate that embryonally the occipital part of the cranium shows 

 great similaiity with the vertebral column. The part of the problem 

 regarding the melamery of the craniuui has ceased to be a problem. 

 At best there is only i(ucstion of the number of metameres, that 

 can be distinguished in the spinal part. The question after the origin 

 and the eventual segmentation of the part in front of the N. vagus 

 still remains. On this point the views are still divided. For us it 

 has for this moment no interest. 



What is interesting for us, is the fact, that the most candal part 

 of the cranium, i. e. the occipiial [lart, shows distiuct proofs of a 

 previous segmentation wliich corresponds entirely with that of the 

 region of tlie vertebral cohunu. It is of importance to emphasize 

 here already that the above mentioned segmentation is a segmenta- 

 tion of metauieres or primordial vertebrae with myotome and sclero- 

 tome, not a segmentation in vertebrae. 



The second problem nieutioned in the beginning is the so-called 

 re-segmentation of the vertebral column (Neugliederung der Wirbel- 

 siinle). The quintessence of this problem is the question, whether the 

 intervertebral joints with a full-grown individual are the same as 

 the- intervals found embryonally between the primordial vertebrae. 

 In other terms, whether the intersegmental and the intervertebral 

 intervals are the same, aud the cartilageous and the osseous verte- 

 brate origiiuite from the sclerotome of one primordial vertebra 

 (metamere.) 



Remak already answered this in the negative. Van Baer admitted 

 still that the embryonal primordial vertebiae correspond with the 

 permanent later vertebrae. Remak showed that in the ])rimordial 

 vertebrae the intervertebral musculature originated, and at the same 

 time the blastema, from which the permanent vertebrae take their 

 origin. According to him the permanent vertebra is formed in this way : 

 The primitive vertebral bodies (sclerotomes they are called at present) 

 originating in the primordial vertebrae (metameres) fuse together, and, 

 at the same time, new intervals come into e.xistence for the secondary 



