THE VASO-MOTOR NERVES 235 



upon the volume of the abdominal organs, the volume of the arm, 

 and the respiration. In like manner the effects of the suggestion 

 of his execution to a hypnotized subject are recorded in Fig. 125. 

 The vaso-motor mechanism is one of the most important of those 

 mechanisms which control the body heat. Stimulation of the nasal 

 mucous membrane causes flushing of the vessels of the head, constric- 

 tion elsewhere, and a rise of arterial pressure. Food in the mouth, 

 or even the sight or smell of food, causes dilatation of the vessels of 

 the salivary gland. The mucous membrane of the air-passages flush 

 and secrete more actively when a draught of cold air strikes the skin. 

 Ice placed on the abdomen constricts not only the vessels in the skin, 

 but those in the kidney. Many other examples might be given of the 

 control which the vaso-motor system exerts, but the above are suffi- 

 cient to suggest the influence which the physician can bring to bear 

 on the blood-supply of the various organs. 



