1090 Proceedings of Royal Society of Edinburgh. [sess. 
sion of auricular or ventricular excitability. The two auricles 
always contracted together, and the two ventricles always contracted 
simultaneously, the condition being identical with heart-block 
experimentally induced. The independence of the ventricular 
rhythm from that of the right auricle was, moreover, manifest on 
examination of the patient by means of the Rontgen rays. 
The constancy and permanence of the heart-block point to it 
being due to some intrinsic cardiac lesion rather than to dromo- 
tropic nerve influence. This view was confirmed by tracings taken 
after the administration of atropin to the patient. 
In fig. 2, a portion of tracings taken after administration of 
atropin is reproduced. The upper tracing is from the jugular and 
carotid movements, the middle tracing is from the right brachial 
artery, the lower tracing is from the apex beat of the heart. The 
tracings show the auricular rate of contraction to be 274*73 per 
minute, while the ventricular rate is 36*58 per minute. The 
heart-block is still complete, and it is therefore due to an intrinsic 
cardiac cause — a lesion, probably chronic interstitial myocarditis, 
involving the auriculo-ventricular bridge. 
The independent auricular contractions have, in this case, never 
given rise to audible sounds. 
REFERENCES. 
(1) Mackenzie, J., The Study of the Pulse , arterial , venous , 
and hepatic , and of the Movements of the Heart , Edin. and 
London, 1902, chap, xxvii. p. 279. 
(2) Finkelnburg, R., Deutsches Arcliiv f. Min. Med., Leipzig, 
1905, Bd. lxxxii. S. 586. 
(3) Hering, H.!E., Archiv f. d. ges. Physiologie , Bonn, 1905, 
Bd. cviii. S. 267. 
(4) His, W., jun., Wiener med. Blatter , Wien, 1894, Bd. xvii. 
S. 653. Also reference in Centralb. f. Physiol ., Leipzig und 
Wien, 1896, Bd. ix. S. 469. 
(5) Humblet, Max, Arch, intern, de physiologie , 1904, tome i. 
