CONTENTS. xv 



SECTION Y. 



THE KEGULATION AND ADAPTATION OF THE VASCULAR MECHANISM. 

 The Regulation of the Beat of the Heart. 



PAGE 



150. The two great regulators ; changes in the heart beat and changes in 



the peripheral mechanism 289 



The Histology of the Heart. 



151. Cardiac muscular tissue. The structure of the frog's heart . . 290 



152. The structure of the mammalian heart 292 



153. The nerves and ganglia of the heart. In the frog. In the mammal 293 



The Development of the Normal Beat. 



154. Graphic record of the heart beat. The beat of the frog's heart. 

 The sequence of events, and the descending scale of rhythmic 

 power 296 



155. The causes of the spontaneous rhythmic beat ; the relations of the 



ganglia ; the features of the cardiac tissue 300 



156. Some features of the heart beat in the mammal .... 305 



The Government of the Heart Beat by the Nervous System. 



157. Inhibition in the frog by stimulation of vagus nerves. Features of 



inhibition 305 



158. Augmentation of the heart beat in the frog. Antagonism of aug- 

 mentation and inhibition. Course of augmentor fibres in the 

 frog 307 



159. Reflex inhibition. Cardio-inhibitory centre 310 



160. Inhibition in the mammal ; effect on blood pressure. Eeflex inhibi- 

 tion. Course of augmentor fibres in the dog .... 311 



161. Nature of augmentor and inhibitory effects. Action of atropin and 



muscarin 318 



Other influences regulating or modifying the Beat of the Heart. 



162. Influences of blood, and substances contained in the blood. Influence 

 of the distension of the cavities. Relation of heart beat to blood- 

 pressure ........... 320 



SECTION VI. 



CHANGES IN THE CALIBRE OF THE MINUTE ARTERIES. VASO-MOTOR 



ACTIONS. 



163. Changes of calibre in arteries as seen in the web of a frog's foot and 



elsewhere. Vaso-motor nerves . 324 



164. The vascular phenomena in a rabbit's ear 325 



