164 THE HUMAN MECHANISM 



compared with the operations of a large army. In spite of 

 the fact that we are for the most part uriconscious of it, it is 

 none the less a part of our daily life; and the fatigue induced 

 within these vasomotor and hormone mechanisms by their 

 continued activity probably contributes a large share to that 

 general bodily fatigue which leads us to seek recuperation 

 in rest and sleep. 



The apparatus, the operation, and the regulation of the 

 flow of blood and lymph afford an excellent illustration of 

 the fact that the human body, at least in this particular, is 

 a complex machine. But while we of to-day look upon it 

 with somewhat less of awe than did our ancestors, and 

 while there is for us less of mystery and more of mechanism 

 in it, we gain, on the other hand, a wholly new revelation 

 of its intricacy and a fresh sense of its marvelous delicacy, 

 beauty, and perfection of adjustment. The mere fact that 

 everyone of us carries in his bosom a powerful double 

 force-pump of remarkable design, original construction, and 

 extraordinary power, capable in many instances of success- 

 ful and unremitting service for more than three quarters of 

 a century, should be, in itself alone, enough to excite admi- 

 ration and respect for the entire mechanism of which it is 

 only one part and to awaken within us a desire to use that 

 mechanism " as not abusing it." 



