i94 THE POPULAR SCIENCE MONTHLY 



the same processes and the same result are best brought about through 

 the combined agencies of food and rest, with sleep. Sleep is here of 

 value since, by its complete inhibition of the more obvious corporeal 

 activities, it makes rest more complete and thus allows the more com- 

 plete elimination of fatigue substances and restoration of those things 

 that are essential to future activity. 



Equally difficult with the problem of the extent to which labor may 

 safety be carried is the problem of how much food, rest and sleep are 

 required for healthful recuperation. How much we think we require 

 is another question, for here again our sensations are misleading and 

 it is easy to acquire habits which bear little relation to nature's demands. 

 We here assembled, being in the shadow of Professor Chittenden's 

 laboratory, are in the very center of the low-protein camp, and with 

 appetites bridled we can safely defy those who tell us to eat what we 

 please, when we please, and all that we please. Tbere is, indeed, little 

 doubt of the correctness of the main contention of Chittenden, Fletcher, 

 Fisher and their followers, that it is physiologically advantageous to 

 consume less protein than most of the civilized races consume, and it is 

 impossible to avoid a strong suspicion that the presence of a super- 

 fluity of food stuffs within the body leads to an accumulation of inter- 

 mediate metabolic products which in themselves act on the tissues as 

 fatigue substances. The physiological optimum in the matter of 

 quantity of food probably differs with each individual and, with our 

 customarily unscientific habits of judging ourselves, is probably rarely 

 known. This is equally true of the amount of rest and sleep required 

 for recuperation. Our fathers told us " eight hours' work, eight hours' 

 rest and eight hours' sleep " — yet did our fathers, more than we, 

 literally observe the adage? As I believe that most of us eat too much, 

 so I believe that most of us work too briefly and rest too long. Yet 

 more significant than duration is intensity. " Work when we work, and 

 play when we play," is not a meaningless nursery jingle, but a wise 

 physiological dictum. Application, concentration, putting our whole 

 selves into our task, with a wholesome disregard of fancied fatigue — 

 that is the method of accomplishment. But when fatigue really comes, 

 then should the task be laid completely aside for restoration. Play is 

 one of the surest agencies for mental relaxation in the waking state. 

 Pathetic was the confession of one of the world's most busy workers a 

 few years before his death, at the age of forty-five, that he had 

 " almost forgotten how to play." Effective sleep should be dreamless, 

 and if it is of the right sort, it need not occupy one third of all our 

 life. For most persons eight hours of actual sleep would mean nine 

 hours in bed — and only a sluggard would demand that. 



Food, rest, play and sleep may be regarded as the effective physiolog- 

 ical antidotes to fatigue. One ingenious German investigator would add 

 to these another. In an experimental study he believes that he has 



