Ivi Journal of Comparative Neurology. 



ganglia upon these nerves, which terminate in the posterior vago-glosso- 

 pharyngeal nucleus and in the gelatinous substance around the fascicu- 

 lus sohtarius (Kdlliker). These facts are confirmed by observation of 

 cases of bulbar paralysis, and by experimental section of the glosso- 

 pharyngeal root. These structures therefore form the nuclei of termi- 

 nation of the combined vago-glossopharyngeal nerve. 



3. The substantia gelalinaa and spongiosa, situated in the lateral 

 parts of the medulla oblongata and pons Varolii, forms the end-nucleus 

 of the so-called ascending trigeminal root, the fibres of which are the 

 axis-cylinder processes of the cells of the Gasserian ganglion (Kolliker). 

 Section of the sensory division of this nerve is followed by degeneration 

 of the ascending root through the gelatinous substance into the substan- 

 tia spongiosa, where the fibres break up into end-tufts. In this situation 

 are cells, chiefly of Golgi's first type, whose axis-cylinder processes pass 

 into the reticular formation. 



4. The motor nucleus of the fifth nerve is the nucleus of origin 

 of most of the fibres of the motor root, the fibres being the axis-cylin- 

 der processes of the large multipolar cells of the nucleus. 



5. The so-called descending trigeminal root is composed of the 

 axis-cylinder processes of the cells in the outer part of the Sylvian grey 

 matter, and joins the motor division of this nerve. It is not improba- 

 ble that this nucleus innervates some of the muscles supplied by the 

 fifth cranial nerve. It is not " trophic" in the sense used by Merkel. 



6. There is no direct cerebellar root of the fifth nerve. What 

 has previously been described as such is a tract of fibres passing be- 

 tween the roof nuclei and the nucleus of Deiters, and probably also 

 between the superior olivary bodies and the roof nuclei of the cerebel- 

 lum (Bruce). 



Homoplasty of the Brain.^ 



The attempt to establish homologies on the basis of external char- 

 acters alone is rapidly being abandoned in most departments of neuro- 

 logical research. The extremes of error to which this method may 

 lead are well illustrated by the homologies current until recently for 

 the various parts of the fish brain. It would seem as if the other ex- 

 treme, that of painstaking experimental localization of homologous 

 functions, were represented in the paper under consideration. The 

 new experiments were performed on hedgehogs {Eri?iaceus) , cats and 

 rabbits. The comparison of the cortical areas of the cat and the dog 



1 Mann, Gustav. On the Homoplasty of the Brain of Rodents, Insect- 

 ivores, and Carnivores. Jour. Anat. and Physiol., N. S., X, i, Oct., 1895. 



