344 THE METABOLISM OF THE CARBOHYDRATES 



ducing impulses resulting from puncture could be blocked by 

 nicotin, we injected the drug subcutaneously and then punctured 

 the medulla, with the results depicted in the following table. 



TABLE IV 



It will be seen that the nicotin had undoubtedly prevented the 

 usual effect of puncture, possibly by its having instituted a block 

 in the sympathetic ganglia. 



All these experiments, however, may not have such a simple 

 interpretation, for in all of them in which it was found that 

 glycosuria did not appear on puncture, there must have been 

 coincidentally established, by the experimental procedure, a 

 condition of extreme splanchnic vasodilatation, and a consequent 

 fall of blood pressure, which alone, as we have shown, is sufficient 

 to cause the glycosuria produced by vagus stimulation in dogs to 

 disappear, or, at least, to become very much less marked. 



For example, if the central end of the vagi be stimulated until 

 the urine becomes strongly saccharine, and the dog be then 

 gradually bled from its femoral artery until the blood pressure 

 has fallen to almost one-third its normal level, it will be found 

 that the sugar disappears from the urine or diminishes markedly 

 in amount ; or, conversely, if the dog be first of all bled until its 

 blood pressure has considerably fallen and the central end of the 

 vagi then stimulated, no glycosuria will be induced. The glycosuria 

 we have found likewise to disappear when the blood pressure has 

 been caused to fall from other causes than bleeding, such as by 

 opening the thorax. 



