XXVI ILLUSTRATIONS 



FIG. PAGE 



33. Optical records of intraventricular pressure 148 



34. Superimposed pressure curves after being graduated 150 



35. Diagram to illustrate optical method for recording pressure curves from 



auricles 152 



36. Diagram to show the positions of the cardiac valves 156 



37. Electrophonograms along with intraventricular pressure curves from three 



different experiments 159 



38. Arrangement of apparatus for heart-lung preparation 164 



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



preparation 169 



40. Heart and cardiac nerves of Limulus polyphemus 173 



41. Heart-block produced by applying clamp 175 



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



cation of heat to the auricle 175 



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



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



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



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



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



46. The effects of successive stimuli and of tetanizing stimuli on skeletal muscle 



and cardiac muscle 179 



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



tion shocks at various moments of the cardiac cycle 180 



48. Heart of tortoise as suspended 183 



49. Dissection of heart to show auriculoventricular bundle 184 



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



constructed from dissections of the heart 184 



51. Diagram of an auricle showing the arrangement of the muscle bands; the 



concentration point; and the outline of the node 186 



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



heart of the mammal 186 



53. 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 



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



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



wave appeared on the front of the heart 194 



56. Diagram of Chauveau's dromograph 200 



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



58. Cybulski's photohematotachometer 201 



59. Dudgeon's sphygmograph 201 



60. Pulse tracing (sphygmogram) taken by sphygmograph 202 



61. Forms of apparatus for measurement of blood velocities 207 



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



63. Effect of venous supply on volume of heart 217 



64. Simultaneous tracings from auricle and ventricle of turtle's heart .... 223 



65. Effect of vagus stimulation on 'heart of turtle 223 



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



auricles to ventricles 224 



