456 



NA TURE 



[September 30, 1922 



Most probably the rhythm selected is only in small 

 part due to the worker's physical configuration; in 

 greater part it is evolved in imitation of some more 

 experienced or older worker. The average workman 

 is not so much concerned with the diminution of the 

 physiological cost in the performance of a given acl 

 as in the reduction of conscious effort. It is not, of 

 course, uggested that the methods adopted by workers 

 independently are the perfect methods, and that 

 proper investigation will not discover better and easier 

 methods of performing certain given operations. If 

 newer and more economical methods are to be de- 

 veloped and brought into operation, the only real 

 chance will be to segregate the newer young workers. 



There is good evidence, that of Muscio, for example, 

 that both resting and working, in addition to the 

 individual muscle rhythm, there is a definite variation 

 in the course of the day in the capacity to carry out 

 work ; that, in other words, a diurnal rhythm exists. 

 There is a certain amount of evidence also in favour of 

 the view that a seasonal rhythm exists. Further, when 

 efficiency is measured in terms of output, it is found 

 that there is a definite rhythm in output during the 

 course of the working day and of the working week. 

 This type of curve is not peculiar to any one industry. 

 The total weekly output curve with the low Monday 

 effect and the sharp fall on Saturday resembles in 

 general shape the daily output curve. The main point 

 aboul these curves is that they seem to demonstrate 

 the absence of progressive fatigue from overwork, 

 which would have been deduced had there been a 

 sharp rise at the commencement of the week, followed 

 by a steady fall. 



The third of the potent factors in the control of 

 fatigue is rest. If work is done, rest is ultimately 

 imperative. Rest not merely relaxes the muscle, 

 allowing a more thorough and complete removal of the 

 waste products and a more abundant supply of oxygen, 

 but it removes the strain of attention. Rest is best 

 obtained, not by simple quiescence, but by change of 

 posture ; slow movement of another type to that which 

 produced the fatigue will, unless the organism is tired 

 practically to complete exhaustion, give the most 

 beneficial results. 



So [ar, little attention has been paid to the duration 

 of the rest period in relation to the work done. As a 

 general rule, it may be said that, in the majority of 

 occupations, although the hours of labour are con- 

 tinuous, the actual spells of hard manual work are 

 discontinuous, either due to the fact that certain 

 operations are intermittent in their severity, that 

 supplies of material are not constant, or that, if these 

 more or less natural conditions do not operate, rests 

 at irregular intervals are deliberately taken by the 

 operative. So far as I am aware there is only one 

 type of hard work where a definite rest period is laid 

 down as part of the exercise, namely, in Army route 

 marching. 



So much, then, for the ordinary effector factors. 

 There are many other factors directly concerned with 

 the efficient action of the organism, some directly 

 influencing the internal economy of the body, others 

 acting more indirectly on the organism from the 

 environment. 



One of these factors is the state of the nutrition. It 



NO. 2761, VOL. I ioj 



may be definitely stated that an insufficient intake of 

 food or the consumption of poor or inadequate food is 

 one of the chief sources of general inefficiencv. The 

 capacity of the body to store reserve food materia] 

 which will meet the daily demands for energy and 

 leave a surplus is another of the vital factors of safety. 

 The much more important problem is unfortunately 

 only too common, the influence of chronic undernutri- 

 tion, a condition which lowers efficiency, not merely in 

 the actual performance of muscular work, but by 

 inducing an increased susceptibility to disease. This 

 is a question which has never received the attention 

 which its importance demands, largely on account of 

 the immense difficulties of carrying out the investiga- 

 tion in a practical manner. As the direct result of 

 the war, we have the records of at least two sets of 

 observers. Benedict and his co-workers investigated 

 the problem, using a group of twelve men, comparing 

 them with a similar group drawn from the same class. 

 In the experimental group the food intake was reduced, 

 so that there was a loss of 12 per cent, of the body 

 weight. Although the experiment was carried on for 

 more than four months, the diminution in muscle 

 power, so far as laboratory tests were concerned, was 

 nut great. The subjective impression, however, of 

 the subjects was that they felt weaker anil less 

 capable. 



The other recorded experiment is that of the condi- 

 tion in Germany during the war vears. A general 

 statement of the effects of the blockade is contained in 

 a long doi anient prepared by the German Government 

 (dated December 1918). Admittedly the document 

 was prepared for a specific purpose ; but, after making 

 all allowances, the record of the far-reaching effects 

 of chronic underfeeding is valuable. Apart from the 

 increased death rate, the increased liability to disease, 

 and the slow recoverv from the attacks of disease; 

 the document definitely states that the working 

 capacity of the people was reduced by at least one- 

 third. Evidence would also indicate that it is not 

 only the quantity but the quality of the food consumed 

 which plays a part in the fitness of the individual to 

 perform hard muscular work. 



Another factor which plays an enormous role in the 

 general efficiency is the response of the organism to the 

 multiple psychic imponderabilia which compose such 

 a large part of the average environment. When we 

 are dealing with the efficiency of the human organism, 

 male and female, we are dealing with individuals 

 whose performance is neither uniform throughout the 

 year nor from week to week, nor even from hour to 

 hour. We have to deal with an organism, as I have 

 already mentioned, which is not only under physical 

 control, but is very responsive to psychic influences. 

 Man is, in the main, a psychic chameleon. 



In this connexion monotony of work must be con- 

 sidered. Although there may be a close relationship 

 between monotony and fatigue, as generally recognised, 

 they are not identical. The temperament of the 

 operative plays an enormous part in determining 

 whether or no any particular operation is a monotonous 

 one. As Munsterberg has shown, it is extremely 

 difficult, if not impossible, for an outsider to determine 

 what is a monotonous operation. 



There are many other factors which play a definite 



