CONTENTS. xxxiii 



SECTION VIII 

 THE LYMPHATIC ARRANGEMENTS OF THE BRAIN AND SPINAL CORD. 



PAGE 



517. The characters of the cerebro-spinal fluid 824 



518. The renewal of the cerebro-spinal fluid. The purposes served by 



the fluid 825 



SECTION IX. 

 THE VASCULAR ARRANGEMENTS OF THE BRAIN AND SPINAL CORD. 



519. The distribution and characters of the arteries of the brain . . 827 



520. The venous arrangements of the brain 828 



521. The supply of blood to the brain relatively small. The methods of 



investigating the circulation of the brain 829 



522. The supply of blood to the brain modified by the respiration and by 



changes in the general arterial pressure. The want of clear 



proof of special vasomotor nerves for the cerebral arteries . . 831 

 523. The flow of blood through the brain nevertheless influenced by 



changes taking place in the brain itself 833 



CHAPTER III. 



SIGHT. 

 SECTION I. 



ON THE GENERAL STRUCTURE OF THE EYE, AND ON THE FORMATION OF 

 THE KETINAL IMAGE. 



524. Dioptic mechanisms and visual impulses . . . . . - . 834 



525. The general structure of the eye. The formation of the retinal 



image 835 



526. A simple optic system ; its cardinal points. The refractive surfaces 



and media of the eye . . . ..... . .839 



527. The optic constants of the eye. The diagrammatic eye . . . 841 



528. The paths of the rays of light through the eye . . . . . 843 



529. The retinal image in relation to the sensations excited by it . . 845 



SECTION II. 

 THE FACTS OF ACCOMMODATION. 



530. The eye can accommodate for far and near objects ; far and near 



limits of accommodation 846 



531. Schemer's experiment 847 



