MEMBRANA PROPRIA OF THE DUCTUS COCHLEARIS. 145 



upon the vessels. Here and there the vessels project in the 

 form of small loops. These last are particularly well marked 

 in Birds, on the roof of the ductus cochlearis in the so-called 

 tegmentum vasculosum (Deiters, 14), which corresponds to the 

 stria vascularis of Mammals. The epithelium of the tegmentum 

 in Birds also presents some peculiarities ; for between the clear 

 cubic cells and I can fully corroborate the statement of 

 Deiters on this point are moderately large nucleated dark 

 granular structures of nearly uniform size, the cell protoplasm 

 of which appears quite like felt. A clear slender portion of 

 irregular triangular or quadrilateral shape, to which small hairs 

 are sometimes attached, projects from the free surface of the 

 felt-like body of the cell. The opposite extremity runs out 

 into a sharp point (fig. 336, E). 



A very well-marked columnar epithelium occurs again in 

 Mammals upon the sulcus spiralis externus. The layer imme- 

 diately subjacent to this consists, in adults, of a homogeneous 

 glass-clear tissue, which is directly continuous with the tri- 

 angular process of the ligamentum spirale, and from thence 

 passes into the homogeneous layer of the basilar membrane * 



A reference given by Schweigger-Seidel (72) shows that 

 Bottcher (4) has again taken up the view of Todd and Bowman 

 (54), long ago set aside by Kolliker (32), to the effect that the 

 ligamentum spirale contains smooth muscular fibres. After 

 much investigation, however, I must coincide with the negative 

 view of the question taken by Kolliker. 



The crista spiralis has presented no slight difficulties to the 

 investigators of the cochlea difficulties in my opinion occa- 



* It does not appear to be agreed upon as to what shall be understood 

 by the term ligamentum spirale. Kolliker, by whom the name was given, 

 as well as Lowenberg, include under it the whole semilunar cushion of con- 

 nective tissue which connects together the external wall of the ductus 

 cochlearis and the capsule of the cochlea. This varies considerably in 

 different species of animals, both in form and size ; sometimes it extends 

 far into the scala tympani, especially in the lower turn of the cochlea, 

 sometimes but a little way (figs. 321 and 322). 1 prefer as Henle also 

 appears to do, to designate by this term only the part of this layer which 

 is triangular in section, and homogeneous in adults, and with which 

 the membrana basilaris is continuous, and which in fact answers to a 

 ligament. 



VOL. III. L 



