308 



AUGMENTATION OF THE BEAT. [BOOK i. 



This being the case we may expect that we should get different 

 results according as we stimulated (1) the vagus in the cranium, 



FlG. 70. DIAGRAMMATIC KEPRESENTATION OF THE COUKSE OF CARDIAC AlJGMENTOB 



FIBRES IN THE FROG. 



Vr. roots of vagus (and ixth) nerve. GV. ganglion of same. Cr. line of cranial 

 wall. Vg. vagus trunk, ix. ninth, glosso-pharyngeal nerve. S.V.C. superior vena 

 cava. Sy. sympathetic nerve in neck. G.G. junction of sympathetic ganglion with 

 vagus ganglion sending i.e. intracranial fibres passing to Gasserian ganglion. The 

 rest of the fibres pass along the vagus trunk. G 1 sympathetic ganglion connected 

 with the first spinal nerve. G u sympathetic ganglion of the second spinal nerve. 

 An.V. annulus of Vieussens. A.sb. subclavian artery. G" 1 sympathetic ganglion of 

 the third spinal nerve. III. third spinal nerve, r.c. ramus communicans. 



The course of the augmentor fibres is shewn by the thick black line. They may 

 be traced from the spinal cord by the anterior root of the third spinal nerve, through 

 the ramus communicans to the corresponding sympathetic ganglion G IU and thence 

 by the second ganglion G 11 , the annulus of Vieussens, and the first ganglion G 1 to 

 the cervical sympathetic Sy, and so by the vagus trunk to the superior vena cava 

 S.V.C. 



before it was joined by the sympathetic, (2) the sympathetic fibres 

 before they join the vagus, and (3) the vagus trunk, containing both 

 the real vagus and the sympathetic fibres. What we have pre- 

 viously described are the ordinary results of stimulating the mixed 



