HARMONY IN MUSIC. 



73 



from its resemblance to the shell of a common garden snail. 

 This spiral passage is divided throughout its length into three 

 sections, upper, middle, and lower, by two membranes stretched 

 in the middle of its height. The Marchese Corti discovered 

 some very remarkable formations in the middle section. They 

 FIG. 8. 



consist of innumerable plates, microscopically small, and 

 arranged orderly side by side, like the keys of a piano. They are 

 connected at one end with the fibres of the auditory nerve, and 

 at the other with the stretched membrane. 



Fig. 8 shows this extraordinarily complicated arrangement 



