122 AVERS. [Vol. VI. 



show the sHg'htest trace of Loewenberg's net, and they are per- 

 fect preparations, I may very safely say, so far as the pres- 

 ervation of the component parts of the organ of Corti is 

 concerned. Chromic acid differentiates the net as well as any 

 other reagent used. In aqueous humor, liquor amnii, and in 

 weak solutions of copper salts the net is not formed. In PI. IV, 

 Fig. 7, is shown a section of the hair band of the Virginia 

 opossum in which the net of Loewenberg appears as an appen- 

 dage of the hair band attached to its outer edge. The sizes of 

 the meshes in the most perfect specimens of the net are, as 

 near as could be measured, the same as the upper ends of the 

 cells of Corti's ridge beyond the last row of hair cells on the 

 outside. The characters possessed by the net in one part of 

 the cochlea may be found to vary from this condition in other 

 parts of the cochlea, and such variation is not exceptional. 

 The coarser, outer cords present, not infrequently, a striate 

 appearance, which is due, I think, to the presence of auditory 

 hairs. The net covers a variable area of the surface of the hair 

 band, but never the entire surface, and usually about, or a little 

 more than, half the surface. When all these facts are consid- 

 ered by themselves, we are left as much in the dark as to the 

 nature of the net and the significance of its attachments as ever. 

 An observation made quite recently on the fonnation of this 

 membrane or network has made clear to me its nature and 

 thrown some light on another structure, the membrana reticu- 

 laris, which remains to be described. A perfectly fresh cochlea 

 of the adult pig was opened in salt solution, to which was 

 added, after five minutes, i per cent chromic acid, and the dis- 

 section proceeded with. As the preparation was being exam- 

 ined under the microscope (Hartnack, obj. 4, oc. 3), a thin film 

 was seen to rise from the surface of the ridge of Corti outside 

 the outer hair cells, i.e. beyond the edge of the hair band, which 

 was still in place, and curve up over the hair band, the motion 

 being around the line of fixation in the edge of the hair band as 

 an axis. This film curved over onto and applied itself closely 

 to the surface of the hair band. This film did not become fixed 

 to the surface of the hair band, as an examination of a portion of 

 the latter structure under a higher power conclusively proved, 

 but remained entirely separated from it, except at the outer edge, 

 where it seemed to pass structurally into the edge and to help 



