388 



Idio- Vent7'icular Periodicity. 



The simplest explanation that occurs to us is that there was a complete 

 heart block between the auricles and ventricle, the former continuing to 

 beat regularly; and that the periodic grouping does not indicate a partial 

 removal of the block but was a ventricular phenomenon ; in other words, 

 that this is an instance of idio-ventricular periodicity. 



It must be understood that we do not advance this explanation for all 

 cases of periodic grouping ; all other tracings that we have seen are able 

 to bear the usual interpretation. Moreover, it is beyond the scope of this 

 note to discuss to what extent, if any, the result may have been due to 

 the action of inositol. 



Summar-)/. 



A perfusion experiment on the excised heart of the frog is described and 

 discussed, in which periodic grouping occurred as an independent ventricular 

 phenomenon. 



