Archives of internal medicine . s 1, 2, 3, the hearts beat for the most part atan accelerated speed, varying from and contractions in two, tobetween 21 and 50 in others. After incision 4, the hearts stopped beating A. E. COHN—L. KE88EL 229 entirely for periods varying from 7 to 92 seconds. Then the rate gradu-ally, but rather rapidly, quickened and remained at an approximatelyfixed speed, always much slower than before the incisions, for the remain-der of the experiment. It happened only once that the auricle ceasedpermanently to contract after the excision of the node-bearing area. I
Archives of internal medicine . s 1, 2, 3, the hearts beat for the most part atan accelerated speed, varying from and contractions in two, tobetween 21 and 50 in others. After incision 4, the hearts stopped beating A. E. COHN—L. KE88EL 229 entirely for periods varying from 7 to 92 seconds. Then the rate gradu-ally, but rather rapidly, quickened and remained at an approximatelyfixed speed, always much slower than before the incisions, for the remain-der of the experiment. It happened only once that the auricle ceasedpermanently to contract after the excision of the node-bearing area. Insome experiments, the auricular systole preceded the ventricular, in othersthe reverse took place, in still others they beat simultaneously. Wecannot conclude from our experiments that a definite anatomical sitetakes up the pace-making function for the entire heart as a substitute forthe sino-auricular node after the sino-auricular node is excised. If vari-ous portions of the heart possess this automatic power, as Keith^ and. Diagram of incisions: S. V. C, superior vena cava; R. A., right auricle:K. A. A., right appendix auricula;; 1, 2, 3, 4, incisions. Erlanger^^ thought, soinetimes one and sometimes another steps in for theusual dominating area, which, if we may conclude from the uniformlyslower rate after its excision, resides normally in the sino-auricular conclusion is not justified from our experiments that simpleincisions cause a stoppage of the whole heart (as Hering states), and thephenomena subsequently noted. We have shown that excision is neces-sary to produce this result. We are led to conclude, therefore, from ourexperiments that, as has long been supposed, and as former experimentshave seemed to indicate, normal impulse formation takes place andnormal rate is produced in the sino-auricular for publication, Aug. 12, 1910. STUDIES OX THE BIOLOGY OF AXD IMMUNITY AGAINSTTHE BACILLUS OF LEPEOSY WITH A CONSIDERATION OF THE POSSIBILITY OF SPEC
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