290 O. VAN DER STRICHT 



future heads are seen two sections (connected with sections of 

 inner pillars), the structures of which have undergone no change. 

 The process of cytolysis is completed at the level of the first 

 nine elements; it is progressing in the following four and has not 

 yet begun in the last two. On comparing these structures with 

 more advanced stages, and especially with those in the adult 

 cochlea, it is plain that the body of the outer pillars acquires its 

 final form and structure by a process of secretion and cytolysis 

 along with the elongation of the intermediate segment. In young 

 cats, bats, common and white rats it becomes a slender fibril- 

 lated strand, destitute of clear cytoplasm (figs. 10, 13^, 14, 15, 

 17 and 18, oph). Betw^een the pillar bodies, as aheady noted 

 by Nuel, are large clefts through which the fluid of the tumiel 

 space and the neighboring space of Nuel intercommunicate. 



The intennediate portions of the inner pillars undergo similar, 

 but never such marked changes. The greater part of their clear 

 cytoplasm disappears, only a very narrow zone of it persisting, 

 so that in young and adult animals the body of the pillar becomes 

 lamellar in shape (fig. 18, ipb) and flattened out in a spiral 

 'direction. It is composed of a, fibrillar lamella and a thin layer 

 of clear protoplasm (fig. 17, iph). Besides the pores traversed 

 by the nerve fibers, no true intercellular clefts sever the inner 

 pillars. 



Along with these alterations and elongation of the pillar bodies, 

 the tunnel space enlarges gradually but considerably, and very 

 soon its radial diameter surpasses that of the two original clear 

 zones belonging to two contiguous pillars. In other words, the 

 fluid accumulated within the cleft exceeds the am.ount of dis- 

 integrated protoplasm. Indeed, the cytolysis occurs in a 

 merocrine glandular cell, which, although undergoing partial 

 liquefaction, is able to elaborate new clear secretion products at 

 the expense of material derived from the vas spirale. Hence the 

 tunnel fluid is the result not only of a sheer cytolysis, but also 

 of a true elaboration and subsequent discharge. In the earliest 

 stages of development the process of cytolysis seems to be more 

 prevalent, since the contents of the cleft are seen in the form of 

 a coagulated, vacuolated mass; afterwards the larger space is 



