454 AVERS. [Vol. VIII. 



appearance of a portion of the nerve bundle within this lymph 

 space, as defined by the Golgi stain. 



D. T/ic Foj-amina nervina of the Habettula perforata. 



All previous observers have described the holes in the habe- 

 nula perforata as slit-like or oval openings, and there is a 

 unanimity of opinion (supposed to be fully justified by repeated 

 observations by scores of observers) that the auditory nerve 

 enters the cochlear canal in regular bundles through these 

 holes. 



It is true some observers have laid special stress upon the 

 fact, admitted by all, that among birds and reptiles the nerves 

 emerge from the basilar membrane, not in bundles, but singly, 

 and also that in the upper end of the organ of Corti in Mam- 

 mals the same method of entrance exists. 



I held the same views until Golgi preparations taught me 

 better. The bundles of nerve fibres from the cochlear ganglion, 

 as they approach the habenula perforata, are not so compact 

 as they appear in ordinary preparations of the cochlea, for the 

 silver stain shows that there are no sharply defined foraviina 

 nervina for bundles of nerves, but that only an approximation 

 to this condition obtains, while many nerve fibres may enter 

 the cochlear canal between any two fibres of the basilar mem- 

 brane, which are thus separated and which may be said to form 

 the boundary of their foramen. Many of the nerves will be 

 found to pass between other fibres of basilar membrane in 

 such a way as to produce irregular groups of fibres (PI. Ill, 

 Fig. 32). In Golgi stains of this region, with the organ of 

 Corti removed, the broken nerves appear as dots, and an in- 

 spection of Fig. 32 will make it clear that there is nearly a 

 continuous series of fibres which find their way through the 

 basilar membrane. Periodically reinforced by larger bundles 

 of fibres more or less closelv packed together, this nearly 

 continuous series of fibres (the Sauropsid condition) assumes 

 the appearance of a series of separate groups here and there 

 continuous and with a tendency (everywhere shown) to fuse 

 together. 



