AND HAIR-CELLS IN THE DEVELOPING ORGAN OF CORTI. 113 



arranged in spiral, parallel rows: an inner row of inner hair cells on the medial side 

 of the inner rods of Corti, and three rows of outer hair-cells on the lateral side of the 

 outer pillars. According to Waldeyer (1872), Retzius (1884), Tafani (1884, 1885), 

 who examined Cercopithecus viridus, and Kolmer (1910), four and occasionally five 

 rows of outer hair-cells exist in man and monkeys; in other mammals a fourth row 

 may appear in some parts of the cochlea. The hairs upon the free surface of all 

 these elements were first described by Deiters (1860), and all authors agree that 

 these sensory epithelial cells are cylindrical in shape and contain a single rounded 

 nucleus in the deeper cytoplasmic portion. Deiters (1860), Hensen (1863, 1873), 

 Middendorp (1867), Loewenberg (1868), Boettcher (1869, 1872), v. Winiwarter 

 (1870), Krause (1876), and Nuel (1878), believed that the cell body of the sensory 

 elements is connected with the basilar membrane by an intermediate deep process. 

 That no such process exists has been conclusively proved by Rosenberg (1868), 

 Retzius (1884), Denis (1901), Vernieuwe (1905), and by all of the more recent 

 observers. All of the other elements of the organ of Corti are held to be supporting 

 cells, and among these two types must be distinguished: 



(1) The two rows of inner and outer pillar cells or rods of Corti: With the excep- 

 tion of Loewenberg (1868), who finds more outer than inner pillars, most investi- 

 gatorsClaudius (1855), Boettcher (1856, 1859), Max Schultze (1858), Middendorp 

 (1867), v. Winiwarter (1870), Krause (1876), Nuel (1878), and many others, com- 

 pute about three inner pillars for two outer; while N. Van der Stricht (1908) 

 proves that the number of inner pillar cells is 'just double the number of the outer 

 pillar cells, of the cells of Deiters of the first and second rows, and of the hair-cells of 

 each row. Tafani (1884) had already noted that the number of outer pillars is 

 exactly the same as the number of hair-cells of each outer row. He stated also that 

 the phalanx apex of the outer pillars is located between two apices of neighboring 

 hair-cells of the first outer row. Many misinterpretations have been published 

 about the development of the pillars. Rosenberg (1868), Boettcher (1869, 1872), 

 and Pritchard (1878) assert that one original cell divides into two, an inner and an 

 outer pillar; whereas Loewenberg (1868), Gottstein (1870), Waldeyer (1872), and 

 Hardesty (1915) regard each pillar as derived from two cells. The investigations of 

 Hensen (1863, 1871), Middendorp (1867), Retzius (1884), Denis (1901), Vernieuwe 

 (1905), and other more recent observers, have proved conclusively that each pillar 

 with its nucleus is originally developed from one cell (the pillar cell). The striated 

 fibrillar structure of the pillars in the adult cochlea has been noted by M. Schultze 

 (1858), Boettcher (1859, 1869), Deiters (1860), Loewenberg (1868), v. Winiwarter 

 (1870), Gottstein (1870), Hensen (1871), Nuel (1872, 1878), Lavdowsky (1876), 

 Retzius (1884), and others; but their actual filamentous structure and the basal body 

 of the outer pillars have been clearly brought out by Joseph (1900), Retzius (1900), 

 v. Spee (1901), Held (1902), N. Van der Stricht (1908), and Kolmer (1910). 



(2) The outer supporting r<V/.s, or the cells of Deiters: According to the investiga- 

 tions of all observers, these cells, like the pillars, are stretched between the basilar 

 membrane and the lamina reticularis. They are composed of a nucleated cell body 



