x CONTENTS. 



67. Chemistry of living muscle ; muscle-plasma, muscle-clot, and muscle- 

 serum, myoglobulin, histo-haematin 89 



58. Acid reaction of rigid muscle ; development of carbonic acid in rigor 



mortis 90 



69. Other constituents of muscle 92 



60. Chemical changes during contraction ; development of carbonic acid 



and acid reaction 94 



61. Summary of the chemistry of muscle 95 



Thermal Changes. 



62. Heat given out during a contraction. Comparison of muscle with a 



steam-engine 95 



Electrical Changes. 



63. Non-polarizable electrodes. Muscle currents ; their distribution and 



nature 97 



64. Negative variation of the muscle current ; currents of action. The 



rheoscopic frog 102 



The Changes in a Nerve during the passage of a Nervous Impulse. 



65. The changes constituting what is called a nervous impulse propa- 

 gated along the nerve 104 



66. The chemistry of a nerve ; cholesterin, lecithin, cerebrin, protagon 105 



67. The nervous impulse ; the electrical changes accompanying it. These 



changes travel in both directions along the nerve .... 106 



68. Summary of the changes occurring in a muscle and nerve as the 



result of stimulation 108 



SECTION III. 



THE NATURE OF THE CHANGES THROUGH WHICH AN ELECTRIC CURRENT 

 IS ABLE TO GENERATE A NERVOUS IMPULSE. 



Action of the Constant Current. 



69. Action of the constant current ; making and breaking contractions . 110 

 70. Electrotonus. Effect of the constant current on the irritability of 



the nerve. Katelectrotonus. Anelectrotonus . . . .112 



71. Electrotonic currents 114 



72. Relation of electrotonus to nervous impulses, and to the effects of 



the constant current 116 



73. Action of the constant current on muscle 118 



