vi 



CONTENTS. 



yielded by alimentary substances is transformed partly into heat 

 and partly into work— Seat of combustion in the organism- 

 Heating of the glands and muscles during their functions— Seat 

 of calorification — Intervention of the causes of cooling — Animal 

 temperature — Automatic regulator of animal temperature . . 19 



CHAPTER IV. 

 ANIMAL MOTION. 

 Motion is the most apparent characteristic of life ; it acts on 

 solids, liquids, and gases — Distinction between the motions of 

 organic and animal life — We shall treat of animal motion only 

 — Structure of the muscles — Undulating appearance of the still 

 living fibre— Muscular Avave— Shock and myography — Multi- 

 plicity of acts of contraction — Intensity of contraction in its 

 relations to the frequency of muscular shocks — Characteristics 

 of fibre at diff'erent points of the body 27 



CHAPTER V. 



CONTKACTION AND WOEK OF THE MUSCLES. 

 The function of the nerve— Speed of the nervous agent— Measures 

 of time in physiology — Tetanus and muscular contraction — 

 Theory of contraction— Action of the muscles .... 41 



CHAPTER VI. 



OF ELECTRICITY IN ANIMALS. 

 Electricity is produced in almost all organised tissues — Electric cur- 

 rents of the muscles and the nerves — Discharge of electric 

 fishes ; old theories ; demonstration of the electric nature of 

 this phenomenon — Analogies between the discharge of electrical 

 apparatus and the shock of a muscle — Electric tetanus — Rapidity 

 of the nervous agent in the electrical nerves of the torpedo ; 

 duration of its discharge 49 



CHAPTER VII. 



ANIMAL MECHANISM. 

 Of the forms under which mechanical work presents itself — Every 

 machine must be constructed with a view to the kind of work 

 which it has to perform — Correspondence of the form of muscle 

 with the work which it accomplishes — Theory of Borelli — 

 Specific force of muscles — Of machines ; they only change the 



