CAUSES OF FATIGUE — ^USE OF ELEVATING LEGS. 535 



boots feel tiglit, and sometimes even a distinct impression may 

 be remarked at that part of the ankle which was uncovered by 

 the boot. In such persons we can actually see the swelling 

 disappear after the feet have been kept rested for some time on 

 a level with the body, and it maybe removed more quickly still 

 by gently and steadily rubbing the limbs in one direction from 

 below upwards. It is almost certain that what we thus see in 

 weakly persons occurs to a slighter extent in all, and that even 

 in the most healthy person after a long walk a slight accumula- 

 tion of fluid, laden with the products of muscular waste, occurs 

 both in the muscles themselves, and in the cellular tissue around 

 them, even although we cannot detect it by simple inspection. 

 So long as the limbs of such a person hang down, the force of 

 gravity retards the return both of blood through the veins and 

 of lymph through the fascia and lymphatics, and thus hinders 

 the muscles from getting rid of those waste products which 

 caused the fatigue. When the legs are raised, this hindrance 

 is at once removed, both blood and lymph return more readily 

 from the muscles, carryiuG: with them those substances which 

 had been formed by the muscles of the limbs during the exer- 

 tions which they had undergone when carrying the body about. 

 So long as these substances remained where they had been 

 formed, they might cause in the muscles of the legs an undue 

 amount of fatigue, although when distributed over the body 

 generally, they may produce only a p] easing languor. When 

 the legs are long, the obstruction to the return of blood and 

 lymph is of course greater than when they are short, and this 

 return will take place more readily when the legs are raised 

 above the body than when they are only on a level with it. 

 This may be one of the reasons why some of our long-legged 

 American cousins are so fond cf raising their feet to a level 

 with their heads, or even higher, although it is very probable 

 that there are reasons still more powerful, which we may discuss 

 at a future time. 



It has already been mentioned that the lymph is propelled 

 along the interstices of the fasciae into the lymphatic vessels by 

 the intermittent pressure which the muscle exerts upon them 

 from within, and it seems natural to suppose that the flow 



