No. 3] AUDITORY OR HAIR^CELLS OF THE EAR. 459 



continuity with the nerve fibres are in many points unlike the 

 hair-cells of Corti's organ, but they are probably, in essentials, 

 the same. A detailed account of them I shall not attempt 

 here but reserve for a later publication. Before adult life is 

 reached this entire organ is resorbed and its place is marked 

 in the mammalian cochlea by the sulcus spiralis internns. Its 

 peripheral hair cells and their central prolongations, with their 

 connections being thus annihilated must leave important 

 changes in the nervous constitution of the growing mammal 

 the history of which has yet to find a student. 



In Figs. 20 and 21, PI, III and in Fig. i, PI. I are shown the 

 peripheral nerve branchings in the Sauropsid organ. The 

 continuity of the hair cells of this organ with the nerve fibres 

 is given in PI. I, Fig. 3, where the cells are seen to be different 

 in shape from those of its offspring the Cortian organ. From 

 all I have seen thus far, however, I am inclined to the view 

 that the two apparently different cells are essentially alike, 

 but no definite conclusions can be drawn from Golgi pictures 

 alone. After leaving the hair-cell the nerve (PI. Ill, Fig. 21) 

 runs directly to the basement membrane of the organ — mem- 

 brana basilaris, and after piercing it bends suddenly inward on 

 its way to the ganglion. Varicosities occur all along the course 

 of the fibres but they are more numerous peripherad of the 

 ganglion than centrad of it. This statement is true for all 

 classes of vertebrates. Here as in the Cortian organ they are 

 found close up to the hair-cells and in case of the fibres 

 from both organs they occur in contact with the ganglion cells. 

 In describing this organ as an embryonic sense organ in my 

 recent paper I had not been able to satisfactorily determine 

 that its cells received nerve fibres in the mammal. I was able 

 to do so however in the case of its homologue in the Alligator. 

 Under the circumstances it is a pleasure to add this further 

 point to our knowledge of the race history of the mammalian 

 stock and another important problem to the endless list already 

 before morphological workers for solution. From an examina- 

 tion of Retzius' figures and Van Gehuchten's account of 

 cochlear innervation I have no doubt that a part of what they 

 have described as nerves in the organ of Corti are really nerves 

 in the Sauropsid organ, and until they distinguish clearly 



