66 THE GENESIS AND STRUCTURE OF THE MEMBRANA TECTORIA 



the real mosaic figured and described later by Lavdowsky (1876), Retzius (1884), 

 N. Van der Stricht (1908), and Held (1909). After treatment by silver nitrate, 

 Lavdowsky notices on the limbus spiralis a layer of small endothelial cells devoid 

 of nuclei, more exactly endothelial plates which are quite distinct from the subjacent 

 cells located within the interdental furrows. 



On the limbus spiralis of rabbit, cat, and man, Retzius, also using silver nitrate, 

 states that the interdental cells situated within the furrows reach the surface and 

 line by their superficial flat apices the prominences, the teeth, and the warts 

 (Warzen). Hence in adult individuals is formed a complete cell mosaic, continuous 

 with the cell-layer of the Reissner's membrane and of the sulcus spiralis. This 

 statement is confirmed by N. Van der Stricht and Held, who used other fixing agents 

 and stained the terminal bars between the apices of the epithelial cells and found 

 a diplosome within each polygon of the mosaic. 



It is to be pointed out that the last three authors, who accurately describe the 

 superficial mosaic and its connections with the teeth and the primitive epithelial 

 cells, do not give exact details of the location of the cell bodies and of the inter- 

 mediary connective tissue, because they did not examine transverse sections of the 

 crista spiralis at different stages in its development. There is no wonder that in 

 many text-books of histology the description of the superficial elements of the crista 

 is partly erroneous. I will content myself with referring to the Histology of Stohr 

 translated by Billstcin, 1898. On page 380 one reads: "the surface of the limbus 

 is covered by a simple layer of flattenedep ithelial cells. " R. Krause, in the Hand- 

 buch der vergleichenden und experimentellen Entwickelungslehre der Wirbelthiere, 

 O. Hertwig, 1900, Bd. 1, p. 118, expresses himself in the following terms: "Die 

 anfangs kubischen Zellen werden ganz platt und bilden eine feine, endothelartige 

 Membran, welche hier den Ductus cochlearis begrcnzt. " In the text-book of 

 Microscopic Anatomy, by E. A. Schafer, 1912, one reads on page 285 that the 

 cells "are continued as a pavement-epithelium over the limbus." In 1909 Vasti- 

 car described very flattened polygonal cells at the surface of the teeth of Huschke . 



In order to get a true picture of the structure of the crista spiralis at various 

 stages in its development, it is necessary to compare tangential sections with the 

 vertical, and to follow, step by step, the formation of the teeth of Huschke and the 

 alterations in the epithelial cells. I will distinguish four stages in succession. 



1 . The first is represented in the second turn of the cochlea from a pig embryo 

 of 93.5 mm. The columnar epithelium is separated from the subjacent connective 

 tissue by a basement-membrane stained blue by Mallory's method and green by 

 light green, and is in continuity with the much thicker epithelium which outlines 

 both ridges. On vertical and somewhat oblique sections this basement-membrane 

 is fenestrated and provided with small openings; small nuclei of connective tissue, 

 cells are incorporated in its thickness, their axis parallel to the surface of the epithe- 

 lium. Beneath the membrane exists an embryonic areolar connective-tissue con- 

 sisting of cells the nuclei of which are stained red by Mallory's method or blue by 

 iron hematoxylin, and surrounded by a very small cytoplasmic zone stained faintly 

 red by fuchsin or rosy by Congo red; this zone is in continuity with prolongations 



