now TUK AMM\:, i,ivi.> 22'J 



G. Work ; Wasti : Rest 

 G'j. Tri/.</f of (is.sin 



4J-. L'lultT luxlily labor, tlio t'lciiu'iits of the 

 muscN's aro used up to a eortaiii extent, while 



ht'at iiiitl waste matters arc protlii 1. A 



l>«M-i<>(l of rest is re<]uire(l to allow for rt'pair o« 

 this wast«'. We see this earried out in all healthy 

 iMitJily funetions. Tlif heart, aftt-r radi contrac- 

 tion, has a short rest before the connnencenient 

 of the next eontraetion. The nniseles that carry 

 «>n breathinjr work in relays, those that <lilate the 

 ehe>t restini^ while those that cniiiid-css the 

 chest are in operation. Then both rest for an 

 interval before the next inspiration is coni- 

 nienctMl, This piovides fur rest and re})air of 

 both the muscles an<l nerves. Except for rucIj 

 rest, botli would soon be «»xhausted and wasted 

 beyond the power of work. 



4_M. The waste of tissues, however, is not 

 always in exact i)roportion to the amount of 

 Work. On the contrary, it has been shown by 

 carefid experiment that tiie waste of the working: 

 nni.scle is but a small part of the expenditure 

 made. The heat- or fat-producinc: matters in 

 the food are also used up in sn<-h work. 

 The process may i»e likened to fuel supplied to 

 the engine, which contributes to keep it runnin;^' 



