No. 3] AUDITORY OR HAIR^CELLS OF THE EAR. 46 1 



in cochlear preparations lying among the supporting cells at 

 the bases of the hair cells. The fibres of the saccular nerve 

 do not always leave the organ as simple fibres but frequently 

 as several branches which soon unite into a single fibre, and 

 finally there are numerous fibres in the simpler sense organs of 

 the ear which take a course at right angles to the long axes of 

 the sense cells and run through the epithelial tissue of the 

 organ for considerable distances. They are varicose fibres 

 showing occasionally collateral branches and they sooner or 

 later bend upward to end in hair-cells or downwards to unite 

 with some other fibre on its way out of the organ, or to make a 

 separate exit by itself. To my mind they are the homologues 

 of the "spiral fibres of the Cortian organ. 



In view of the facts above recited we may fairly conclude: 



1. That hair-cell and bi- or multipolar cells of the cochlear 

 ganglion — are both parts of a single morphological unit — the 

 acoustic element which mediates between points at the surface 

 and points in the nervous centre. 



2. That there is no fundamental difference between the 

 acoustic and olfactive elements yet made known. 



3. That all fibres of the auditory nerve proceed out of hair- 

 cells alone so far as has yet been satisfactorily determined. 



4. That the so-called spiral fibres are but parts of individual 

 radial fibres bent to a right angle, more or less, out of their 

 course. They are in some cases the product of the lateral 

 branches of the cochlear nerves within the organ of Corti, the 

 region of the lamina or the cochlear ganglion itself. 



5. That in the mammalian embryo the auditory nerve is at 

 one time mostly composed of nerve processes arising in the 

 Sauropsid organ, and that as this organ fades away and the mam- 

 malian ors:an increases in size the nerve becomes more and more 

 a bundle of fibres from the acoustic cells of this latter organ. 



6. That so far as we yet know there is no special significance 

 to be attached to the fact that the majority of the cells of the 

 cochlear ganglion are "bipolar" though intermixed with an im- 

 portant minority of multipolar cells of from 3 to 6 processes. 



The Lake Laboratory, 



Milwaukee, Jan. 5, 1893. 



