INHIBITION AND CARDIAC VAGUS 99 



When any man dies of sudden heart failure without 

 cardiac disease or degeneration it is commonly attributed 

 to "shock." Whatever "shock" may be, and something 

 relevant to the subject may be urged later, it is usually 

 brought about by violent stimulation of an unusual kind, 

 such as severe trauma with its concomitant results. It is 

 obvious that the heart, especially in delicately balanced 

 organisms, is subject to continual fluctuations in its rate 

 and energy. In it any excitatory, or depressant, stimuli 

 bring about reflex cardiac results, in which, doubtless, the 

 vagus is often implicated. In a minor degree they, too, 

 may often be said to suffer from shock, for in that con- 

 dition the state of the circulation is a major factor. If 

 they are depressed there is weakening and slowing of the 

 heart, a possible accumulation of blood in the abdominal 

 veins, or even some loss of the fluid constituents of the blood 

 by failure of osmotic balance, such as seen in undoubted 

 traumatic shock (Bayliss), temporary anaemia of the brain, 

 collapse, and possibly loss of consciousness. Such results, 

 although they may upon occasion save the life of those 

 who suffer from them, are undoubtedly dangerous, and in 

 that sense pathological. It seems possible, then, that the 

 equivalent or allied phenomena seen in animals, when the 

 cut vagus is stimulated artificially, may be of a similar 

 kind, and that any physiological deductions as to the 

 action of the cardiac vagus are, to say the least, some- 

 what hasty. 



Since shock has been of late the subject of much re- 

 search, and of especially valuable practical work by 

 Bayliss, something at least is known of its nature. Judg- 

 ing, however, from recent notices of it in medical journals, 

 it is to be observed that the main symptoms of severe, or 

 possibly lethal, shock only are dilated upon. The influence 



