THE HEART 259 



haps 30 or 40 beats per minute. At the same moment 

 when the low count is obtained at the wrist the jugular 

 vein may be seen to pulsate 75 times a minute, a normal 

 frequency. Now the throb of any artery corresponds 

 with the beat of the left ventricle while the pulsation of 

 a vein is in the rhythm of the right auricle. Therefore 

 it is clear that in a case of Stokes-Adams disease there 

 is a failure on the part of the ventricles to adopt the 

 pace of the auricles. In other words this is an instance 

 of heart-block. 



A somewhat whimsical but useful comparison may be 

 made between the auricle and ventricle on the one hand 

 and a certain type of married couple on the other. 

 We often see a wife of slight physique but great vivacity 

 and ambition who compels a stalwart but naturally 

 phlegmatic husband to maintain the pace which she sets 

 for him. If we pursue the analogy we shall see in 

 Stokes-Adams disease the suggestion of a declaration of 

 independence on the part of the husband, an assertion of 

 his right to take his own time on the way. 



It is known, as the result of a great body of research, 

 that the automatic property of cardiac muscle is not 

 exhibited unless the solution bathing the tissue contains 

 certain mineral constituents in definite proportions. 

 This is true whether we speak of blood or of some more 

 simple substitute. The salts most certainly necessary 

 are sodium, calcium, and potassium compounds. The 

 subject is interesting but the details must be sought in 

 larger books. 



Another subject which we can do no more than indi- 

 cate is the question whether the automaticity of heart 

 tissue is a property of the contractile cells or of nervous 

 elements associated with them. Exceedingly small 

 fragments of the organ may carry on rhythmic activity, 

 but it is difficult to be sure that these bits do not contain 

 nervous as well as muscular units. Most physiologists 

 are inclined to believe that the automatic tendency is 

 inherent in the cells of cardiac muscle, but the view that 



