776 THE POPULAR SCIENCE MONTHLY. 



may have local exhaustion as when the muscles of our arm are no 

 longer able to hold out a heavy weight or we may have general ex- 

 haustion, as in sleep ; and we may have local restorations due to nutri- 

 tion as when our exhausted arm, after some interval of rest, is aerain 

 able to sustain the weight or we may have a general restoration due 

 to nutrition, as in the effects of sleep. 



I have now said enough about the physiology of nutrition to ren- 

 der quite clear what I mean by recreation depending on the physiologi- 

 cal necessity for a frequent change of organic activity. For although 

 in the case of some organs such as most of the secreting organs 

 activity is pretty constant, owing to the constant expenditure of en- 

 ergy being just about balanced by the constant income, in the case of 

 nerves and muscles this is not so ; during the times when these organs 

 are in activity their expenditure of energy is so vastly greater than 

 their income during the same times, that they can only do their work 

 by drawing upon the stores of energy which have been laid up by 

 them during the comparatively long periods of their previous rest. 

 Now. recreation applies only to nerve and muscle ; and what it amounts 

 to is simply this a change of organic activity, having for its object 

 the affording of time for the nutrition of exhausted portions of the 

 body. A part of the body having become exhausted by work done, 

 and yet the whole of the body not being exhausted so far as to require 

 sleep, recreation is the affording of local sleep to the exhausted part 

 by transferring the scene of activity from it to some other part. Be 

 it observed that a certain amount of activity is necessary for the life 

 and health of all the organs of the body ; so it would not do for the 

 community of organs as a whole that, when any one set become ex- 

 hausted by their own activity, all the others should share in their time 

 of rest, as in general sleep. But, by transferring the state of activity 

 from organs already exhausted by work to organs which are ready 

 nourished to perform work, recreation may be termed, as I have said, 

 local sleep. 



Thus we see that, in a physiological no less than in a psychological 

 sense, the term re-creation is a singularly happy one ; for we see that, 

 as a matter of fact, the whole physiology of recreation consists merely 

 of a re-building up, re-forming, or re-creation of tissues which have 

 become partly broken down by the exhausting effects of work. So 

 that in this physiological sense recreation is partial sleep, while sleep 

 is universal recreation. And now we see why it is that the one essen- 

 tial principle of all recreation must be that of variety of organic activ- 

 ity ; for variety of organic activity merely means the substitution of 

 one set of organic activities for another, and consequently the succes- 

 sive affording of rest to bodily structures as they are successively 

 exhausted. The undergraduate finds recreation in rowing because it 

 gives his brain time to recover its exhausted energies, while the his- 

 torian and the man of science find recreation in each other's labors 



