No. I.] THE VERTEBRATE EAR. 65. 



the lymphatic canals of the ear, as was supposed by Deiters 

 and Lavdovvsky. The basilar membrane, considered phylo- 

 genetically, is merely a portion of the connective-tissue floor 

 of the sense-organ canal of fishes. 



Of the basilar membrane Retzius says {loc. cit. p. 280), 

 ^^ Diese wichtige JMeinbran, die Grttudmenibran des akiistischen 

 Apparates der ScJienecke, welche von Labium tympanicum bis 

 zum Ligamentum spirale straff ausgespannt liegt, lasst sich 

 am ehesten in die eigentliche Membran und die tympanale Belg- 

 schicht theilen." The lining tissue of the scali tympani or the 

 lymph space normally developed below the floor of the sense 

 organ is as normal a component of the basilar membrane as 

 the cellular plate which covers the face of Reissner's mem- 

 brane turned towards the scala vestibuli, and must be con- 

 sidered when we estimate the physical properties of the basilar 

 membrane. 



The importance of the basilar membrane to previous investi- 

 gators was due mainly, if not entirely, to their views as to its 

 function. It was the harp of many chords on which Helmholtz 

 played with variations his later piano-string theory of musical 

 perception. On PL VITI, Figs. 5 and 7 show the basilar mem- 

 brane of the Opossum and its component layers, some of 

 which are strictly transverse, while others run longitudinally, 

 crossing the former nearly at right angles. These fibres are 

 all beld together as a compact plate during life, and are with 

 difficulty separated enough to show their mutual relations. 

 When hardened or properly macerated, they may be readily 

 separated, and the upper layers are most readily displaced. 

 These upper bundles of fibres have played an interesting part 

 in the history of the mammalian cochlea, as will be further 

 explained when we come to treat of the nerves. The histologi- 

 cal character of this membrane has been so many times the sub- 

 ject of careful research that it might seem presumptuous for 

 one to attempt to add anything to our knowledge of it. I do 

 not intend to enter into any long account of the condition of 

 the basilar membrane in the forms studied by me, but only to 

 call attention to the facts (and illustrate them with a few camera 

 drawings) that investigators have ascribed to the membrana 

 basilaris qualities which it certainly does not possess. Its elas- 

 ticity is not great enough to serve for the transmission of the 



