8 



Scientific Proceedings (50). 



ventricle is often followed by a premature beat of the auricle. 

 When the evidence of such retrograde contractions is best, the 

 indicated time of backward conduction is 7/30 to 8/30 of a second. 



8. There is no evidence of lengthened As-Vs intervals except 

 at the extra-systoles. 



9. There is a fairly fixed time relation between the normal 

 and abnormal ventricular systoles. 



10. There is often a considerable delay in the appearance of 

 the carotid pulse resulting from the extra-systole. 



1 1 . There is a marked lack of synchronism between the carotid 

 pulse and the "c" wave. The latter may precede the former by 

 1/20 of a second. 



12. The site of the abnormal stimulus is either in the ventricle 

 or some part of the conduction system, e. g., the node, or some 

 lower point. 



6 (702) 



On the differences in the effects of stimulation of the two vagus 

 nerves on rate and conduction of the dog's heart. 



By Alfred E. Cohn. 



[From the Hospital of the Rockefeller Institute for Medical Research, 



New York.] 



The effects obtained in the action of dogs' hearts on stimulating 

 the peripheral stumps of both vagus nerves were studied in fifty- 

 four experiments. The dogs were anesthetized with ether without 

 adjuvant, artificial respiration was maintained by the Meltzer- 

 Auer method, and registration was accomplished by the galvano- 

 metric method. When the chest was opened, curves of auricular 

 and ventricular contractions were also inscribed. Faradic stimula- 

 tion was employed. The secondary coil of an inductorium, fed 

 by a 2-volt dry cell, placed arbitrarily at 50 mm., was the source 

 of the current. 



On stimulating the right vagus nerve, the usual effect was 

 obtained; both auricles and ventricles ceased to beat, generally 

 throughout the period of stimulation. Occasionally the ventricles 

 escaped from inhibition, but then the impulse to contraction arose 



