THE FUNDAMENTAL PHYSIOLOGICAL ACTIONS 17 



the Body possesses many merely physical properties, as weight, 

 rigidity, elasticity, color, and so on; but in addition to these we 

 find in it while alive many others which it ceases to manifest at 

 death. Of these perhaps the power of executing spontaneous 

 movements and of maintaining a high bodily temperature arc the 

 most marked. As long as the Body is alive it is- warm and, since 

 the surrounding air is nearly always cooler, must be losing heat all 

 day long to neighboring objects; nevertheless we are at the end of 

 the day as warm as at the beginning, the temperature of the Body 

 in health not varying much from 37 C. (98.4 F.), so that clearly 

 our Bodies must be making heat somehow all the time. After 

 death this production of heat ceases and the Body cools down to 

 the temperature in its neighborhood ; but so closely do we associate 

 with it the idea of warmth that the sensation experienced on touch- 

 ing a corpse produces so powerful an impression as commonly to 

 be described as icy cold. The other great characteristic of the liv- 

 ing Body is its power of executing movements ; so long as life lasts 

 it is never at rest ; even in the deepest slumber the regular breath- 

 ing, the tap of the heart against the chest-wall, and the beat of the 

 pulse tell us that we are watching sleep and not death. If to this 

 we add the possession of consciousness by the living Body, whether 

 aroused or not by forces immediately acting upon sense-organs, we 

 might describe it as a heat-producing, moving, conscious organism. 

 The production of heat in the Body needs fuel of some kind as 

 much as its production in a fire ; and every time we move ourselves 

 or external objects some of the Body is used up to supply the neces- 

 sary working power, just as some coals are burnt in the furnace of 

 an engine for every bit of work it does; in the same way every 

 thought that arises in us is accompanied with the destruction of 

 some part of the Body. Hence these primary actions of keeping 

 warm, moving, and being conscious, necessitate many others for 

 the supply of new materials to the tissues concerned and for the 

 removal of their wastes; still others are necessary to regulate the 

 production and loss of heat in accordance with changes in the ex- 

 terior temperature, to bring the moving tissues into relation with 

 the thinking, and so on. By such subsidiary arrangements the 

 working of the whole Body becomes so complex that it would fill 

 many pages merely to enumerate what is known of the duties of its 

 various parts. However, all the proper physiological properties 



