XXVI ILLUSTRATIONS 



FIG. PAGE. 



33. Optical records of intraventricular pressure 147 



34. Superimposed pressure curves after being graduated 149 



35. Von Frank's maximal and minimal valve, which is placed in -the course of 



the tube between heart and mercury manometer 152 



36. Diagram to show the positions of the cardiac valves 155 



37. Diagram showing the position of the cardiac chambers and valves during 



presystole and during the sphymic period 156 



38. Elcctrophonograms along with intraventricular pressure curves from three 



different experiments 159 



39. One form of apparatus for recording tracings from an excised heart . . 163 



40. Volume curve of ventricles of cat (lower curve) in a heart-lung perfusion 



preparation 169 



41. Heart and cardiac nerves of Limulus polyphemus 173 



42. Heart-block produced by applying clamp 175 



43. Tracing of contraction of ventricle, showing the effect of the local appli- 



cation of heat to the auricle . . 175 



44. Frog heart showing the position of the first and second ligatures of Stannius 176 



45. Effects of stimuli of increasing strength on skeletal and cardiac muscle to 



illustrate the "all or nothing" principle in the latter 177 



46. The effects of successive stimuli on skeletal and cardiac muscle to show the 



prominence of the staircase phenomenon, or treppe, in the latter . . 178 



47. The effects, of successive stimuli and of tetanizing stimuli on skeletal muscle 



and cardiac muscle 179 



48. Myograms of frog's ventricle, showing effect of excitation by break induc- 



tion shocks at various moments of the cardiac cycle 180 



49. Heart of tortoise as suspended 183 



50. Dissection of heart to show auriculoventricular bundle 184 



51. Photograph of model of the auriculoventricular bundle and its ramifications, 



constructed from dissections of the heart 184 



52. Diagram of an auricle showing the arrangemoit of the muscle bands; the 



concentration point; and the outline of the node 186 



53. Diagram to show the general ramifications of the conducting tissue in the 



heart of the mammal 186 



54. Diagram to illustrate the development and spread of the wave of negativity 



in a strip of muscle (curarized sartorius) when stimulated at the end . 188 



55. Simultaneous electrocardiograms to show the cause for extrinsic deflections 190 



56. Diagram of experiment by Lewis showing the times at which the excitation 



wave appeared on the front of the heart 194 



57. Diagram of Chauveau's dromograph 200 



58. Diagram to show principle of Pitot's tubes for measuring velocity pulse . . 201 



60. Dudgeon's sphygmograph 201 



61. Pulse tracing (sphygmogram) taken by sphygmograph 202 



62. Forms of apparatus for measurement of blood velocities 207 



63. Plethysmograph for recording volume changes in the hand and forearm . 210 



64. Simultaneous tracings from auricle and ventricle of turtle's heart . . . 218 



65. Effect of vagus stimulation on heart of turtle 218 



66. Tracing to show that vagus stimulation may diminish transmission from 



auricles to ventricles 219 



