George E. Shambaugh 249 
Corti. The membrana tectoria has always proved to be the most elusive 
of all the delicate structures of the membranous labyrinth to study. Its 
delicate semi-fluid substance is such that it is most readily distorted by 
the fixing and hardening agents necessary in preparing the labyrinth for 
histological study. Our ideas of the character and relations of this 
membrane must be made up from a study of these distortions since a 
membrana tectoria in its normal relations that has not been acted upon 
by fixing and hardening agents has never been studied. A conception 
of the variety of distortions which this delicate film-like structure under- 
goes in the process of preparation for histological study can be got by 
glancing over the different drawings of this membrane that have appeared 
in the published works on the labyrinth. In studying the membrana 
tectoria in preparations from a large number of labyrinths, I am certain 
that this membrane does not float free is the endolymph above the organ 
of Corti, but that this position, wnich is the one usually described, is 
the result of the shrinking of this structure owing to the fixing agents. 
This fact is quite evident from the study of such preparations as the 
one shown in Fig. 4. Here, although more or less shrunken and dis- 
torted, the membrana tectoria is still found attached to the organ of 
Corti. The explanation of the spiral band found on the under surface 
of the membrane, which is known as the “ Streifen of Hensen,” is here 
made clear. It is a sort of facet where normally the membrane is at- 
tached to the supporting cells just internal to the inner row of hair cells. 
In this particular preparation, the membrane is only partially lifted from 
its normal position and the “ Streifen of Hensen” is still glued to the 
supporting cells of the organ of Corti, which have in turn been somewhat 
pulled out owing to the partial withdrawal of the membrana tectoria. 
Another fact shown in this preparation is that the hairs of the hair cells 
project into the under surface of the tectorial membrane. That these 
hairs actually penetrate the membrana tectoria and are not merely 
brought into touch with it by accident is well shown by the preparation 
) 
in Fig. 5. Here the membrana tectoria has been partially torn away from 
its moorings, so much so, indeed, that the “ Streifen of Hensen” is no 
longer in contact with the supporting cells and the membrane has also 
been detached from the inner hair cell. The hairs of the three outer 
hair cells, however, are still inserted into the tectorial membrane, which, 
as the result of shrinking, has suffered a distortion in its delicate struc- 
ture which could result only from a more or less close adherence of the 
hairs to this membrane. This relation between tectorial membrane and 
