456 AVERS. [Vol. VIII. 



very most. Their views are not sustained by the facts of adult 

 anatomy. It will however be impossible to throw satisfactory 

 light upon this matter until the development has been worked 

 out with completeness. It may not be a waste of words to 

 record the following conclusions which have grown out of my 

 study of the innervation of the ear. Although tentative they 

 have the harmonious support of the facts of adult anatomy 

 and involve at the same time an explanation of the histogenetic 

 processes which is entirely probable on account of the fact 

 that the nerve process is continuous with the hair-cell (this 

 point I have just recently verified by the Methylen-blue 

 method which gives the needed histological details of the con- 

 tinuity wanting in the Golgi preparations) and we may thus hold 

 that the hair-cell is a genuine nerve cell and the cell of origin 

 of the auditory nerve fibre. The ganglion cell which lies at a 

 distance from the hair-cell in the canalis ganglionaris of the 

 adult was at the very least, in contact with the hair-cell at an 

 early stage of its development for the ganglion is continuous 

 with the superficial layer of cells of the embryo which become 

 the superficial hair-cells of the adult. As development pro 

 ceeds we know that the ganglion recedes further and further 

 into the head until it reaches its adult position. My assump- 

 tion is this — during the multiplication of the sense organ 

 rudiment in early stages, the ganglion cells are the product of 

 the division of the superficial hair-cells, and as development pro- 

 ceeds the protoplasmic bridge left over from an incomplete 

 cell division is drawn out into a fine thread — the fibre which 

 crosses the lamina of the adult. Either before or soon after 

 this bipartition of the primitive sense cell began the centrad 

 process started for the brain from the proximal end of the 

 primitive sense cell which of course, in the adult, remains the 

 proximal end of the ganglion cell. In case of the division of 

 the superficial hair-cell the impulse ^ generated in it would of 

 course travel to the other end of the cell and cause a like 

 division of the ganglion cell so that we should expect to find 

 bipolar cells in the ganglion, and they are there in abundance. 

 But we also find many multipolar cells whose presence is only 



^ Impulse to division in a plane at right angles to the first division. 



