52 (222) Society for Experimental Biology and Medicine. 



than the impulses of the other end. With a strip showing these 

 reactions it is possible to repeat all of the phenomena that can be 

 obtained from a mammalian heart in block produced by compres- 

 sion of the auriculoYentricular bundle. 



These facts suggest the following theory of heart -block : Clamp- 

 ing the auriculoYentricular bundle reduces the efficiency of the 

 cardiac impulses that reach the Yentricles. With a certain degree 

 of pressure the impulses become subminimal with respect to the 

 irritability- of the Yentricles. Such an impulse therefore fails to 

 elicit a contraction of the Yentricles. The next following auricular 

 impulse is no stronger than the preceding one, but in the in- 

 terval the irritability- of the Yentricles has increased to the extent 

 that the weakened auricular impulse then acts as an efficient stimu- 

 lus. In this state of affairs the rhythm would be 2 : 1. A further 

 reduction in the efficiency of the auricular impulse would give higher 

 degrees of partial block and finally complete block. With this 

 theory as a basis it becomes possible to explain all of the impor- 

 tant phenomena of heart-block. 



29 (121). "On the nature of the reflexes controlling the suc- 

 cessive movements in the mechanism of deglutition " : S. J. 

 MELTZER. 



The entire act of deglutition consists of a series of consecutive 

 movements beginning with the elevation of the mylohyoid muscle 

 of the floor of the mouth, progressing through pharynx and esoph- 

 agus and terminating with the contraction of the cardia at the 

 entrance of the stomach. The progress of these movements is 

 surprisingly well regulated and stable. Each section of this canal 

 enters into the peristaltic movement invariably at a given interval 

 after the beginning of the swallowing. The time allowed for the 

 entire course differs with each species of animal ; it is about 7 sec- 

 onds for the human being, about four seconds for the dog, and 

 about 2 seconds for the rabbit. 



It was early recognized that these stable relations were under 

 the control of a reflex mechanism. That the contractions could 

 not be caused by a direct stimulation of the muscle coat of the 

 esophagus by the passing food was proved by the fact that there 

 is no peristalsis when the vagi are cut. In a series of experiments 



