CONTENTS. x i x 



CHAPTER XI. 



CHEMICAL HISTOEY OF CEETAIN OF THE PEEIPHEEAL TEEMI- 

 NATIONB OF THE NEEVOUS SYSTEM AND OF THE AC- 

 CESSOEY STEUCTUEES CONNECTED WITH THEM, THE 

 TISSUES AND MEDIA OF THE EAE, THE TISSUES AND 

 MEDIA OF THE EYE. 



PAGE 



SECT. 1. THE TISSUES AND MEDIA OF THE EAR 448 



Perilymph and Endolyrnph . . . . . . . 449 



Otoliths, Lapilli, or Otoconia 449 



The membranous Labyrinth 450 



SECT. 2. THE TISSUES AND MEDIA OF THE EYE 450 



The Cornea 450 



Sclerotic 451 



Aqueous Humor 452 



Crystalline Lens . . 452 



The Choroid 454 



THE EETINA. 



Introductory 454 



Chemical composition of the Eetina as a whole . . . 459 



General chemical facts relating to Eods and Cones .... 459 



Colouring matters associated with the Cones (Chromophanes) . . 460 

 Colouring matters associated with the Eods (Visual Purple or Eho- 



dopsin) . . 461 



Chemical facts relating to the Eetinal Epithelium .... 468 



Action of light upon the Visual Purple of the Living Eye . . 469 



Eegeneration of Visual Purple 469 



INDEX 471 



