70 THE ACTIVE FORCES OF LIVING ORGANISMS 



by producing effects which on the whole are opposed 

 to the predominating condition, be that one of hyper- 

 contraction or of hyper -expansion and relaxation. 

 There are many ways of increasing oxidation in the 

 nerve-cells, and some of these may be supposed to 

 produce by reaction a constricting effect on the blood- 

 vessels. Meat in general, and especially raw meat 

 or a fresh extract of meat in which the action of the 

 hsemoglobin has not been destroyed, stimulates oxida- 

 tion. Whether they do this by reason of the chemical 

 constituents with which they enrich the blood, or by 

 causing a reflex action through the nerves of the 

 stomach, is hard to say; but carnivorous animals 

 are undoubtedly those in which muscular contractility 

 is most developed, and which at the same time are 

 most inclined to give themselves up to long periods 

 of inaction. It is usually supposed that a cold bath 

 produces a bracing or constricting effect, and though 

 there is apparently no reason for doubting this, it is 

 by no means clear how this result is brought about. 

 The tissues in general, and especially certain parts, 

 such as the hands and feet, show a tendency to swell 

 with heat and to become constricted under the influence 

 of cold. Heat, moreover, is more conducive to chemical 

 action than cold. Is the effect of a cold bath, we may 

 therefore ask, mainly a direct one accompanied by 

 dynamic changes in the vibrations of the nerve-cells, 

 or is it an indirect one caused by vaso-motor action 

 at the periphery and in the nervous system ? When 

 cold water is applied in sufficient quantity to the skin. 



