36 IRVING HARDESTY 



the Louisiana hogs average older and smaller at killing than 

 those in California. All the fetuses here used were obtained in 

 New Orleans. 



In fetuses of about 5 cm. (fig. 5), the coiUng outgrowth of the 

 cochlear pouch has already acquired nearly three turns. Only 

 the first indications are then appearing of the liquefaction of 

 the mesenchyme, the progress of which gives the scalae on the 

 two sides of the cochlear duct. Along the basal side of the 

 cochlear duct the epithelium has already become much thicker 

 than that of the apical side, but as yet there is no differentiation 

 of the epithelium into the greater and lesser epithehal ridges of 

 the later stages. Upon the axio-basal surface of the epithelium 

 of the cochlear duct appears the ) .^ginning of the tectorial mem- 

 brane (TM, fig. 5), being produced by the thicker epithelium. 

 In the sections of embedded material, this product appears 

 densely but finely fibrillar. The fibrils may be seen continuous 

 with the apical ends of the long cylindrical cells, but in the whole 

 product they appear very much tangled and matted together 

 as though an interfibrillar substance were insufficient in either 

 amount or quality to individually support them. When com- 

 pared with the body of the membrane of the later stages, one 

 receives the impression that the fibrils here, which represent 

 the apical ends of the fibrils of the later stages, are smaller than 

 in the later stages. As may be noted by comparison with the 

 figures following, the extreme axial edge of the young mem- 

 brane {AZ, fig. 5), though very thin, is almost as thick as it is 

 in the later stages. The cells producing this edge never become 

 higher, never become so actively productive of the membrane 

 as those of the remainder of the thick epithelium, and they 

 grade into the non-productive cells of the duct. The outer edge 

 of the young membrane is likewise thin at this stage, the cells 

 producing it grading likewise from the less productive into the 

 non-productive cells. However, the outer edge of the thicker 

 epithelium grows in width and activity along with the rest of the 

 thickening. The entire thickness of the tectorial membrane 

 so far produced in figure 5, only represents a part of the width 

 of what I have called the peripheral condensation on the apical 



