52 Dr. A. D. Waller. Various Inclinations of the 



In the left superior record the variation is large and fairly regular between 

 values = 26 mm. in expiration and = 18 mm. in inspiration. 



The right and left measurements give for the superior angle « above the 

 heart the following values : — 

 In expiration — 



In inspiration — 



18-7-5 10-5 nA1 OOQ 

 tana = 18T^5 = 2-F5 = °- 41 ' a = 22 ' 



Diff. = 12° 



From these results we see that in the case of an oblique heart the effect of 

 inspiration is to weaken the strong leads and to strengthen the weak leads. But 

 this rule, while affording a useful mnemonic, is applicable only to oblique and 

 vertical hearts.* The inspiratory diminution of the superior angle has in this 

 case come out as 12°, as compared with 24° for the inferior angle. This is as 

 might be expected from the fact that the basal attachment of the heart 

 cannot be rotated to the same extent as its apical free portion. Obviously 

 we cannot expect that the angle calculated above the heart from the three 

 points M, E, L, should necessarily be identical with that calculated below the 

 heart from the three points F, E, L. 



(The records of this case incidentally afford a striking example of the 

 variations of pulse-frequency that are associated with the two phases of 

 respiration, sometimes in the human subject, always in the dog. I have 

 discussed them elsewhere under the title " Dog Pulse."f Their consideration 

 does not belong to this portion of the subject.) 



The Case of A. D. W. — A Heart of the Horizontal Type. 



Fig. 3 gives the transverse, right inferior, and left inferior records taken 

 simultaneously with a record of respiration, slow and deep so as to emphasise 

 the effects upon the heart, which in this subject had been determined as 

 having an approximately horizontal electrical axis. The spikes of the weak 

 leads (right superior and left inferior) are accordingly reversed, as was 

 explained in Part I. 



In the transverse records the respiratory variations of the spike are regular 

 and large, between values = 15 mm. in expiration and = 10 mm. in inspira- 

 tion. It may be noticed in this record that inspiratory diminution goes on 



* I speak of hearts as " vertical, 3 ' " oblique," and " horizontal," according as the axial 

 angle a is between 0° and 30°, 30° and 60°, 60° and 90°. The contrasted types are vertical 

 and horizontal ; oblique hearts belong to the vertical type. 



t 'Physiol. Soc. Proc., ; June 28, 1913. 



