CONTENTS. 



CHAPTER XXII. 



OF TOUCH, AND THE DETERMINATION OF PRESSURES AND TEMPERATURES. 

 Functions of the tactile Mechanism : its Structure. Regions of different Sensitiveness. Compar- 

 ative Physiology of Touch. Estimate of physical Qualities. 

 Perception of Temperature. Subjective Sensations of Temperature Page 417 



CHAPTER XXHL 



OF SMELLING, AND THE MEANS OF DISTINGUISHING GASEOUS AND VAPOROUS SUB- 

 STANCES. 



Structure of the Organ of Smell. Its proper Instrument the First Pair of Nerves. Limited Re- 

 gion of Smell. Conditions of its perfect Action. Duration of Odors. Their localization. 

 Subjective Odors 423 



CHAPTER XXTV. 

 OF TASTE. 



Conditions for Taste. Structure and Functions of the Tongue. Tactile and Gustative Regions 

 of the Tongue. Complementary Tastes. Subjective Tastes 427 



CHAPTER XXV. 



OF ANIMAL MOTION. 



Ciliary and Muscular Motion. Description of Cilia and the Manner of Action. 



Muscular Fibre : its Forms, Non-striated and Striated. Muscle Juice. Manner of Contraction 

 of a Muscle : its supply of Blood-vessels and Nerves. Its Chemical Change during Activity. 

 Its Rise of Temperature. Effect of Electrical Currents. Duration of Contractility. 



Doctrine that Muscle Contraction is the result of Muscle Disintegration. Manner in which ordi- 

 nary Cohesion is brought into play. Manner of Restoration. Removal of the Heat and Oxi- 

 dized Bodies. 



Rigor Mortis. Connection of Muscle for Locomotion. Of Standing. Walking. Running. 431 



BOOK II. 



DYNAMICAL PHYSIOLOGY. 

 COURSE OF LIFE. 



CHAPTER I. 

 OF THE PRINCIPLE OF ORGANIZATION, OR PLASTIC POWER. 



Remarks on the Subdivision of Physiology. 



Career of an Organic Form. Three Modes of Development. 



Inquiry respecting the special Principle of Organization. Illustration from the Growth of a Plant 



in Darkness and Light. Inference respecting Plastic Power : its Nature and Properties. 



Of the ordinary Growth of a Plant, and the Sources from which its Materials are derived. 

 Relation of all Organisms to each other. 

 Correction of the Doctrine of a Plastic Power, from Considerations regarding the Individuality 



of a Plant. Plants are Operations, not Individuals. Physical Illustration of this View. 

 Conclusion respecting the Nature of the Plastic Power: that it is a continued Manifestation of an 



antecedent physical Impression ^56 



