266 Journal of Comparative Neurology. 



centers, Mayser's description of the lesions of the spinal cord 

 experimentally produced, and above all the wonderfully clear 

 results of Forel shown in Fig. 9. The specimen represented 

 there is a section from the medulla oblongata of a guinea-pig 

 in which the right pneumogastric had been pulled out soon af- 

 ter birth. The consequence was degeneration of the segmental 

 motor neurones of the tenth and also of the segmental afferent 

 neurones, which have their cell-bodies in the jugular ganglia ; 

 all the cells of the motor tenth are atrophied and degenerated, 

 and all the cells of the 'sensory nucleus' have moved more 

 closely together. On .the healthy (left) side, these cells are 

 separated by broader spaces of ground-substance or ' spongy 

 substance. ' The end-arborizations of the afferent neurones 

 of the tenth nerve form part of this spongy substance and 

 their degeneration brings about a considerable reduction of 

 the spaces. An instance of the conditions following a lesion 

 of the auditory segmental afferent elements is quoted further 

 on. The whole connection between the afferent and efferent 

 and intermediate neurones is rather a matter of schematic illus- 

 tration than of accurate histological knowledge. Special affec- 

 tions of the reflex-collaterals and the fibers to the columns of 

 Clarke, and further early degeneration of the thin root-fibers 

 (Lissauer's zone) have been described in tabes, but they are 

 neither correlated with cell-bodies of special character nor with 

 sufficiently well isolated functions in the clinical picture. 



Van Gehuchten calls the peripheral branch of the neural 

 process a dendrite and the central branch a neurite, probably in 

 order to save the general doctrine that the ' current ' or im- 

 pulse is carried from the end of the dendrite through the cell- 

 body to the axone. This seems to be against the facts re- 

 vealed by Lugaro. The general laiv of conduction, as just 

 stated, must probably be sacrificed. The section of a peripheral 

 nerve producing exactly the same lesion in an afferent and in 

 an efferent neurone, puts them on equal footing as neurites 

 (axones) and if one fiber is to be identified with the name den- 

 drite, it is undoubtedly the one which ends in the neural tube, 

 both on account of its numerous ramifications and the peculiar 



