No. 3-] AUDITORY OR HAIR-CELLS OF THE EAR. 457 



to be accounted for by supposing that the impulses to division 

 sent onward from the periphery have not influenced the gang- 

 lion for some cause not now conspicuous. And finally, some 

 of the divisions do not reach the ganglion cell, and thus give 

 rise to branching fibres between the ganglion and hair-cells. As 

 a result we would get from this process exactly what we find in 

 the ganglion and organ of Corti, viz., a single ganglion cell 

 with two or more hair-cells connected with it by nerve fibres 

 while only one nerve fibre proceeds from the ganglion cell to 

 the nerve centre. 



Most of the complicated figures and groups formed by hair- 

 cells and nerves in the organ of Certi lend themselves to this 

 explanation while I have failed to find any other satisfactory 

 view applicable to the sensory structures of the whole ear. 

 Only a detailed knowledge of the histogenesis of this organ 

 can determine the full story of this process. 



The cochlear ganglion (PI. I, Fig. i), is an elongate cylin- 

 drical body, spirally twisted to fit the helical inclination of the 

 proximal portion of the lamina ossea which is here channeled 

 by a lack of ossification. This canalis ganglionaris or Rosen- 

 thal's^ canal of the human ear, is marked by the successive 

 enlargements and constrictions of the cord of ganglion cells 

 and nerve fibres which it contains and which really represents 

 a chain of ganglionic bodies. A radial section passing ver- 

 tically through the helix and through one of these enlargements 

 shows the maximum size of the ganglion. The cells are quite 

 regularly distributed through the body of the ganglion and are 

 separated by the passing nerve fibres and the network of blood 

 capillaries which riddle the ganglionic body, and which unite 

 with a more compact vascular network forming a cover to the 

 mass of ganglion cells. Most of the ganglion cells are bipolar, 

 but multipolar cells (Pi. II, Figs. 12 and 13), are not uncom- 

 mon (3-6 processes). Most bipolar cells have the nerve fibre 

 running through them radially as this is defined above, but 

 others are so placed that the fibre passes not directly out of the 

 ganglion, but follows along in among the cells in one of the two 

 directions, to sooner or later emerge from the body and make 



1 By an inadvertence this was printed Rosenberg's canal in my recent memoir. 



