148 



HEALTH AND DISEASE 



Slow pulse as distinguished from infrequent is due to the slow con- 

 traction of the ventricles, so that each beat is prolonged independently of 

 the number of beats in a given time. 



Eeference has already been made to the sphygmograph, which is used 

 for the purpose of obtaining a tracing of the pulse. This instrument has 



Fig. 494. — Sphygmograph Diagrams of the Pulse (after Sanderson, Dudgeon, and Steell) 



In. the Human Subject. — 1, Normal healthy pulse: a, systolic wave produced by contraction of left 

 ventricle; b, apex of upstroke indicating highest pressure; c, downstroke; rf, first tidal or predicrotic wave; 

 e, aortic notch, probably indicating the end of the systolic and commencement of the diastolic action of 

 the heart; /, dicrotic wave due to sudden closure of aortic valves; g, second tidal wave; g to /(, period of 

 rest (after Dudgeon). 2, Feeble pulse of age (weak contractility of artery). 3, Senile pulse (muscle failure 

 of heart). 4, Hard wiry pulse of rheumatic fever. 5, Hard and long pulse of hypertrophy of left ventricle 

 with dilatation. 6, Soft pulse of irritative fever. 7, Nervous excitement. 8, Mitral and aortic disease. 



hi the Horse. — 9, Tracing from the facial artery (normal). 10, From the same animal, after the 

 destruction of the aortic valves, showing absence of the dicrotic wave. 



11, Htematograph. Blood spurted from a human artery received upon a revolving drum, showing 

 systolic and dicrotic waves (after Landois). 



not come into use in general practice, nor is it probable that it will for 

 some time at least replace the ordinary method of taking the pulse ; never- 

 theless, it may be interesting to examine the above illustrations, which 

 show very clearly how the different tracings are interpreted; and further 

 information on the subject will be found in the treatises on the sphyg- 

 mograph by Dudgeon, Steell, and others. 



With regard to the respiratory system, symptoms having reference to 



