OP THE NERVUS OCTAVUS 167 



(collaterals) issue taking their way through the raphe in MONAKOW'S 

 system. In relation with the anatomical views here defended it 

 may be easily understood, that the removal of one cochlea needs 

 give only very slight motor disorders, and that these disorders are 

 necessarily of the same kind as those following the removal of one 

 labyrinth, but less intense and of shorter duration. 



For, the. dorsal root is the smaller one of the two roots of the 

 nervus octavus. The number of its fibres may be estimated to be 

 one fourth of that of the ventral root. Moreover the greater part 

 of the dorsal root fibres enters into the stratum latero-dorsale and 

 the octavo-motor systems receive a much smaller quantity of fibres 

 from this layer than from the medial trunk of the rootfibres. 



No wonder that the motor symptoms following the one-sided 

 loss of the dorsal rootfibres are less intense and more apt to cor- 

 rection by the remainings of the octavo-motor system, than those 

 after the loss of the whole labyrinth on one side. 



On the other hand the dorsal root prevails in the innervation 

 of the ventral octavus nucleus and of the tuberculum acusticum 

 above the ventral root, and it henceforth is evident, that the loss 

 of fibres participating to the crossed octavus-system , may be intense 

 after cochlea-removal. Ventral rootfibres participating to this system 

 are however numerous enough to justify the presumption of their 

 influencing to a rather important degree upon this system, the 

 function of which was presumed to be the conduct of the perception 

 of sound. 1 do not see any contradiction between the here defended 

 views and the known facts. 



From the contents of the vestibulum the macula sacculi has its 

 own nerve and this nerve issues from the cochlear nerve. Hence 

 this fact does not argue in favour of a sharp functional difference 

 between the macula sacculi and the cochlea, and the macula sacculi 

 has great morphological relations with the macula vestibuli. 



The morphological differences between the roots founded upon the 

 presence of thick or of small fibres found in them, are also relative. 



It is easily assumed, that a differentiation of the static organ 

 into a cochlea and a vestibular organ, did never lead to a total 

 but only to a partial separation of two functions, existing both in 

 the organ, from which the differentiation took place. Why should 

 animals having no cochlea or an incomplete developed one, not 

 perceive sounds? 



Theoretically it offers no difficulties to assume, that the original 

 static organ did not lose all its existing contacts with the sensory 

 system, and that the new differentiated one, the cochlea, did retain 



