274 



MANUAL OF PHYSIOLOGY. 



tigations, for the microscope shows that there are many ganglion 

 cells distributed throughout the heart-tissue, and that they are 

 located just where we should expect from the above facts. That 



FIG. 122. 



Diagrammatic Plan of the Cardiac Nerve Mechanism. The direction of 

 the impulses is indicated by the arrows. Both right and left sides of the 

 cut are used to show one complete lateral half of the fibres. 



is to say, there are none in the substance of the ventricles, while 

 there are several groups of cells scattered around its base in the 

 auriculo-ventricular groove (Bidder). There are others in the 



