XV111 



CONTENTS 



CHAPTER XVII contd. 



The Receptor Mechanism in General 



cont't. 



Weber's Law- ... - 513 



The Receptors in the Skin - - 514 



Protopathic and Epicritic Sensibility - 514 



Smell - --- - 515 



Photo-Receptors 515 



Accommodation 517 



Movements of Cones - ... 519 



" Dermatoptic Function '' - - 520 

 The Visual Purple- 



Electrical Changes - - 522 



Colour Vision ~>24 



Photo- Receptors contd. 



Mosaic Vision .... ,V25 



Receptors for Sound- - .V_V> 



Position Receptors - - 527 



Statocysts - - 527 



Labyrinth or Semicircular Canals - 528 



Combinations of Sensations - - 5'2!t 



Receptors in Plants .V_".i 



Touch .">_". i 



Gravity- ">-'. 



Light ">:*< i 



Summary - ">.'5n 



Literature 532 



CHAPTER XVIII 



Tonus of Smooth Muscles of Various Kinds 



The Blood Vessels 



Reaction to Stretching - ... 



The Muscles of the Chromatophores of 

 the Cephalopod 



The Adductor Muscle of Anodonta 

 The "Catch" Mechanism in Smooth 

 Muscle ..---- 



Pecten - - - 



The Spines of the Sea Urchin 



Sipunculus 



The Urinary Bladder - 



Metabolism 



Hardness 



Electrical Change - 



TONUS 



533 

 533 

 534 



534 

 534 



534 

 534 

 537 

 537 

 537 

 538 

 538 

 539 



The Auricle of the Tortoise - - - 540 



Tonus in Skeletal Muscle ... 540 



Plastic Tonus - - - - .~>m 



Inhibition .... 541 



Metabolism - - 541 



Heat Production - - .">43 



Electrical Change - - 543 



Production of Creatine, etc. - - ">4.S 



Relation to Labyrinth - ... 543 



Relation to Sympathetic Nerves - "> l."> 



Tonus in Nerve Centres - - 546 



Summary .... 546 



Literature 547 



CHAPTER XIX 

 THE ACTION OF LIGHT 



Absorption of Light - ... 548 



Laws of Lambert and of Beer - - 650 



Extinction Coefficient ... - 550 



Resonance 551 



Spectrophotometry .... 551 



General Theory of Photo-chemical Action - .V> 1 



Photo-chemical Reactions Themselves - 553 



Classification- ..... 553 



Simple Reactions with Increase of 



Energy ... - 553 



Complex Reactions with Increase of 



Energy 554 



Couplea Reactions with Loss of 



Energy - - 554 



Catalytic Reactions with Loss of 



Energy - - - - - - 554 



Optical Sensitisation - - - 555 

 Relation of Velocity of Reaction to In- 

 tensity of Light .... 55(j 



Bunsen-Roscoe Law .... 55^ 



Inertia .... . 555 



Fluorescence 556 



Phosphorescence 557 



Chemi-luminescence - .... 557 



Photo-electric Effects - - - - 558 



The Chlorophyll System - - 558 



History 558 



The Chlorophyll System contd. 



General Nature of the Reaction - - 558 



Chemistry of Chlorophyll - - 558 



Chlorophyll and Haemoglobin - - 560 



Absorption of Light by Chlorophyll - - .~>ti-J 



The Structure on the Chloroplast 563 



The Photo-chemical Reactions of the 



Chlorophyll System - .">r,.s 



Electrical Changes 567 



Red and Brown Seaweeds - - 567 



Complementary Chromatic Adaptation 567 



Factors affecting Photo-synthesis - 568 



The Efficiency of the Chlorophyll System 568 



The Action of Ultra-Violet Light - 569 



The Eye Media 571 



Hallwachs' Effect 571 



Photo-dynamic Sensitisation - 571 



Effect of Light on Growth - 572 



On Permeability - - "t'l 



The Photo-chemistry of the Retina - ">7."> 



The " Chromatic Function " - - - ">7"> 



Radio-active Phenomena - - - 575 



X-rays 576 



Photography in Physiology 576 



Summary - - - 576 



Literature 579 



