NEKVES IN THE MEMBRANA TYMPANI OF MAN 103 



at which two or more branches may be given off ; these he regarded 

 as probably ganglion cells; 



(e) in the plexus under the stratum Malpighii many bi- and 

 multipolar ganglion cells. 



It is no easy task to obtain good results in investigating the 

 nerves of this membrane. Like most of the investigators — 

 Jacques, Calamida and Deinike — I find that ordinary staining 

 methods are inapplicable. Osmic acid, apart from its limi- 

 tations to medullated nerves, so blackens the tissue as to make 

 it difficult to follow the nerve. Gold and silver salts cause so 

 great a precipitate as to make them unsuitable for satisfactory 

 work. Methylene blue is here an ideal method. The very thin- 

 ness of the membrane, so objectionable for the other methods, 

 renders it for this the more suitable. It is the method I have 

 chiefly used; at times I have found a useful substitute in a com- 

 bination of methylene blue and osmic acid. 



The method employed in this research was as follows: after 

 removal of the brain, the petrous temporal bone was loosened 

 from the adjacent parts by means of a small chisel and then care- 

 fully lifted out, cutting with a knife its fibrous and muscular 

 attachments below. It comes away easily, leaving the tympanic 

 membrane intact in the tympanic bone with the malleus attached 

 to it. Usually the incus remains attached to the malleus; the 

 stapes always comes away with the petrous portion. It is of 

 some interest from the operative point of view to note that the 

 attachment of the foot plate of the stapes to the foramen ovale 

 is firmer than that of the incus to the stapes. 



The edges of the membrana tympani and the adjacent part of 

 the covering of the external auditory meatus are now loosened 

 and removed leaving the malleus still attached. By this means 

 there can be detached the whole drum membrane with as much 

 of its mucous layer extension to the middle ear and of the cuticular 

 layer to the external meatus as may be desired. These are im- 

 mersed in a weak solution of methylene blue (three to six drops of 

 a J per cent solution in 20 cc. of normal salt solution), which has 

 been warmed to a temperature of 37° C. The tissue in this solu- 

 tion is placed in a thermostat at 37° C. for three to eight minutes. 



