THE ACTIVE FORCES OF LIVING ORGANISMS 89 



evidence of both vaso- constriction and diminished 

 oxidation. Severe indigestion is also frequently due 

 to a similar state of excessive vaso- constriction and 

 diminished oxidation, and habitual sleepiness may be 

 attributed to the same cause. Amongst the signs of 

 relaxation, due to a predominance of the expansive 

 tendency, are hot hands and feet, insomnia, and con- 

 stipation. 



In respect to the influence which a cold bath with 

 a marked reaction may exercise through the vaso- 

 motor centres, the first point to consider is the 

 continuous character of vaso-motor action. Bach 

 beat of the heart causes movements of expansion and 

 contraction in the whole arterial system which are 

 intensified by the bath. That this pulsation is lost 

 before it reaches the capillaries and tissues is well 

 known, so that it is impossible to trace any direct 

 effect on metabolism in this direction. On the other 

 hand, however, it is perhaps not impossible that a 

 dynamic effect may be produced upon the whole 

 nervous system, owing to its relations to the vaso- 

 motor centres, in which case the character of the 

 metabolic processes would be affected. But whether 

 the nervous system, and with it metabolism in general, 

 be influenced by heat and cold directly or only through 

 the medium of vaso-motor action, the effects produced 

 on the one are felt in like manner in the other. 

 Constriction of the bloodvessels, in any part if at all 

 excessive, as in the case of cold feet, must inevitably 

 be accompanied by a corresponding diminution of 



