No. I.] THE VERTEBRATE EAR. 59 



in their upper parts, while their basal portions, around and below 

 the nucleus, contain a coarsely granular protoplasm. There is 

 not much variation in shape between the cells from the different 

 mammals studied. In all species the basal end of the cylinder 

 is quite regular, somewhat swollen, and the upper rim of the 

 cell wall, where it joins the cell cap, turned out like a flange. 

 This conformation gives the whole cell, when viewed from the 

 side, a vase-like shape. The action of reagents on the cell 

 contents affects their appearance, so that the clear upper half, 

 so distinct in the living cell, may be coagulated or have its 

 invisible structure more or less clearly brought to sight. Con- 

 trary to the statements of Retzius, the auditory hairs arise, 

 as Waldeyer has already claimed, from the whole upper surface 

 of the cell cap. The crescentic outline or horseshoe figure 

 (hufeisen oder halbkreisformiger Anordnung) or style of ar- 

 rangement which Retzius has made us familiar with, is an optical 

 effect and entirely illusory. The explanation of this mistake 

 (which many other investigators besides Retzius have likewise 

 made) lies in the fact of the oblique position of the hair-cell cap 

 with respect to the focal plane of the observer's lenses, so that 

 unless great care and a sufficiently high power is used, the appar- 

 ent arrangement of the hairs in the optical section of tbf" cell cap 

 of the thickness of the focal depth is mistaken for the actual 

 arrangement, which is usually only to be determined by a care- 

 ful analysis and combination of the several images of the optical 

 sections of any given cell cap. Whatever the shape of the cell 

 cap, whether circular, oval, polygonal, or irregular, the hairs 

 arise from the whole of the upper surface, and they are evenly 

 distributed over this surface. 



These hairs are more numerous on the hair cells from man's 

 ear than the mammals which I have studied. The differences 

 are not very great between man, the ox, and pig. Quantitative 

 results I shall reserve for a later paper. 



Retzius has shown conclusively enough that the human coch- 

 lea does not contain a larger number of rows of hair-bearing 

 cells than that of most mammals, e.g. the dog and cat ; but his 

 calculations show the rows to be much longer in man than in 

 the cat and rabbit. 



The row of inner hair cells offers some important points for 

 consideration, — points of difference in structure and perhaps 



