The jSTature of the Tectorial Membrane 113 



fluid was found unsuitable, though, in addition to its alcohol and 

 chloroform, it contains acetic acid. PerenAd's fluid was found impos- 

 sible, for, while it fixes with little or no shrinkage, and decalcifies well, 

 it has a softening and macerating effect unless followed by washing in 

 alcohol, which latter produces violent shrinkage. Depuis, '94, teased 

 after fixing with Miiller's fluid and with chromic acid, both of which 

 decalcify and neither of which causes shrinkage, but he does not seem 

 to have obtained whole or even long pieces of the tectorial membrane. 

 Both of these reagents were found to act so slowly that they were 

 deemed undesirable. Gilson's fluid fixes and decalcifies more rapidly 

 and was found to give much better results than any of the above. 



The best results were obtained with Zenker's fluid, which contains the 

 bichromate of potassium, the bichloride of mercury and acetic acid, all 

 of which have a decalcifying action and none of which, combined, seemed 

 to cause shrinkage or distortion of the tectorial membrane. Furthermore, 

 as is well known, a prolonged application of this fluid is less injurious to 

 tissues than are most of the fixing fluids, and cochlese immersed in it 

 very seldom show the bubbles of gas within the membranous labyrinth, 

 always produced by the more rapid decalcifying agents, and which 

 disturb the arrangement of the structures within. It was found that 

 48 hours in this fluid resulted in good fixation and sufficient decalcifica- 

 tion for the purpose in mind. The entire apex and the outer, thin 

 bony wall of the entire coil were softened, while the thicker base and 

 basal portion of the modiolus were still hard. This undecalcified base 

 and core were found of considerable advantage in holding the specimen 

 firmly during the careful process of teasing. 



Eemoved from the fluid, the cochlea were washed an hour or more in 

 water and teased under the dissecting microscope in a petri-dish con- 

 taining enough water to well cover the specimen. Holding the specimen 

 down firmly by the semi-circular canals and vestibular portion, it was 

 found that, with practice and the exercise of care, the outer portion of 

 the decalcified bony wall of the coil could be stripped off in pieces, 

 leaving the membranous labyrinth intact and not even crumpled. The 

 next task was to remove the outer membranous wall of the scala vestibuli 

 without injury to the structures below it. The vestibular (Eeissner's) 

 membrane was found to be fixed stiff in itself, and, being very loosely 

 attached along its edges, it could be removed, board-like, and taken out of 

 the way ; but in doing this the tectorial membrane, easily identified below 

 it, was necessarily disturbed and sometimes injured. Only after the 



