116 WARFARE IN THE HUMAN BODY 



doses of digitalis no doubt slow or stop recuperative 

 cardiac processes as well as many others. 



In such conceptions there is no mystery, and no neces- 

 sity for the hypothesis that the vagus, acting as a trigger, 

 releases some particular compound which weakens the 

 heart. If in 1906 Sherrington used the expression "in- 

 hibition, whatever that essentially may be," it is far more 

 likely that its nature will be discovered by resort to what 

 we know already, than to such unevolutionary notions of 

 "weakening." It seems that H. O. Thomas, who was not 

 only interested in bone surgery, came to the conclusion 

 that "inhibition is the suspension of life, not the action of 

 special nerves." That he meant by the "suspension of 

 life " some reflexly caused cessation of action is literally 

 certain. He actually writes in 1883 : " In proof that 

 mechanical irritation of this nerve (vagus) induces a con- 

 dition of shock, we have the accepted fact that atropine 

 protects the nerve from the shock consequent on mechanical 

 disturbance. I have not yet met with any evidence which 

 proves the existence of any inhibiting nerve fibres in this or 

 any other nerve." In these views it seems, according to 

 Rushbrooke, that Thomas followed Joseph Lister, also of 

 Liverpool, who wrote on the subject in 1859. Although 

 most, if not all, modern physiologists are certain that 

 inhibition exists, and that it is centrally caused, it seems 

 that the doctrine cannot be looked on as established. If 

 physiology is to make secure its final " passage to physics," 

 which physiologists, who do not resort to vitalism, are 

 working for, some means must surely be found to reconcile 

 the contradictions in cardiac and intestinal vagal action. 

 Perhaps some of the dissatisfaction with current theory can 

 be obviated by means of a different terminology, in which 

 the "lessened action" of reciprocal innervation, that seen 



