48o 



NA TURE 



[SePTKMHER 6, IQOt) 



l)i('n given to Prof. Chittenden and his colleagues by the 

 American Government, and they have studied, not only 

 themselves, but athletes in training and squads of soldiers, 

 and have constantly found that by gradually accustom- 

 ing these men to a carbohydrate diet a condition of 

 physical efficiency and nitrogenous equilibrium can be 

 obtained, though with some loss of weight. As the result 

 of this gradual process the proteid might be reduced until 

 only about 7 grams or 8 grams of nitrogen were excreted 

 daily. 



.•\ctual figures of nitrogenous output were given by Dr. 

 J. M. Hamill and Mr. E. P. Poulton ; the former with 

 Dr. Schryver has investigated the nitrogenous output of 

 the workers in the physiological laboratory of University 

 College, London ; the latter has experimented upon an 

 Oxford student, act. twenty-two, while he was going 

 through the ordinary routine of university life at Oxford. 

 There was great disparity amongst their figures. The 

 workers at University College varied from 8 grams to 

 16 grams of nitrogen daily, whilst -Mr. Poulton's figure 

 was a high one. 



The low nitrogen values indicated above are of great 

 scientific interest, but from the practical point of view they 

 were shown to be of ralher academic value by Dr. Hopkins. 

 He made it quite clear that the observers who had obtained 

 these values for the daily nitrogen output had done so on 

 diets which were many times more expensive than those to 

 which the working classes had access. He showed, in fact, 

 ih.it such food as a working man could buy must have a 

 nitrogen value and a calorie value which was of the order 

 indicated by Voit. The point at issue, then, between Dr. 

 Hopkins and Mr. Rowntree was whether the moderate 

 diet indicated by Voit or the more considerable one in- 

 dicated by Atwater was to be taken as the basis of a 

 proper daily allowance for the working classes. Now 

 though there is a considerable difference between these two 

 diets it is clear that there are lines along which a solution 

 may be forthcoming. Three such directions were indicated 

 by Dr. Hopkins :— 



( 1 ) More searching analyses must be made into the 

 nature of foodstuffs (and this point was developed by Prof. 

 Armstrong). Maize, for instance, is particularly unsuit- 

 able as a staple dietary, not because it is of insufficient 

 nitrogen value or even of insufficient calorie value, but 

 because a particular kind of proteid, which is necessary to 

 growth, is conspicuously absent from maize. 



(2) The relative values of the various tissues as energy 

 transformers must be attested. This work is being carried 

 on by a committee of the British Association, and its annual 

 reports for the past three years have been very instructive, 

 but only the fringe of this large subject has been touched. 



(3) Conditions of age and sex have not been thoroughly 

 investigated. It seems clear that a developing individual — 

 say of twenty years — requires a richer diet than a man 

 of twice that age. 



Dr. Hopkins readily conceded that even the trained 

 alhlete or the soldier might transform much less energy 

 ll>,in was entailed in the daily toil of a bricklayer or a 

 rivetter, and in view of this uncertainty we have some 

 sympathy with Mr. Row-nlree's contention that the calorie 

 value demanded by .Atwater, if acquired in the form of 

 bad food eaten amid unappetising surroundings, was none 

 too much for a heavy day's work. 



•Another discussion of great interest, entitled " The 

 Physiological Value of Rest," was introduced by Dr. 

 Theodore Dyke Acland and Dr. Bevan Lewis. The former 

 dealt chiefly with the hours of rest prescribed in the large 

 public schools of this country. His views are so well 

 kncwn that it is not necessary to give them at length. 

 The discussion was useful from several points of view, 

 which may be briefly summarised : — 



(i) The necessity of obtaining scientific data concerning 

 f.itigue phenomena. This matter was dealt with by several 

 of the pioneers in that branch of physiology, namely, 

 psychophysics, which is rapidly springing up, and which 

 bids fair to yield far-reaching results. Dr. Rivers, Prof. 

 McDougall, and Dr. Myers indicated how the question 

 might be approached on strictly scientific. lines. 



(2) The necessity for limiting the prevalent idea that 

 "recreation is a change of occupation." This dictum is 



NO. 1923, VOL. 74] 



useful and true so long as occupation does not amount to 

 fatigue, but its utility ends at this point. When the system 

 becomes fatigued, and this is especially true of the brain, 

 the toxic bodies produced affect unused as well as used 

 cells. It is futile to throw these cells, already prejudiced,, 

 into activity. Such action simply adds to the amount of 

 poisonous or toxic bodies in the circulation. This point 

 was worked out with great clearness by Dr. Bevan Lewis, 

 whose introductory address was on very different lines from 

 l-hat of Dr. Acland. Dr. Lewis treated the subject from 

 a neurological, not a statistical, standpoint ; he opened 

 with a defence of the " neuron tlieory," now assailed from 

 so many quarters, and on this theory worked out a con- 

 ception of the neurological basis of rest and of fatigue. 

 The practical outcome of his argument, as well as of Dr. 

 .Acland's, was that physical exercise was no substitute for 

 sleep, but that active physical exertion added to severe 

 mental strain demanded a double meed of slumber. In 

 illustration of this point Dr. .\cland recounted how that 

 Mr. C. B. Fry. at once a scholar and an athlete, fre- 

 quently slept till midday or even late in the afternoon 

 during his school vacations, and in doing so gratified 

 nothing more than the healthy demand of his frame — 

 physical and mental — for rest. 



(3) This discussion made clear the individual differences 

 in the depth and time of slumber ; thus day workers attairt 

 the maximum soundness of sleep early in the night, whilst 

 night workers begin their slumber by sleeping somewhat 

 lightly and sleep more soundly as morning approaches. 

 Neurotic subjects, on the other hand, have two maxima on 

 their sleep curve, one in the early part of the night, another 

 in the morning; between these there is a period of shallow- 

 sleep. If any occurrence happens which causes a general 

 reduction in depth of slumber, the period of shallow sleep 

 in the middle of the night is replaced by a period of wake- 

 fulness. 



(4)- Prof. Gotch, who showed the utmost skill in weaving 

 the separate items of this discussion into a continuum, 

 dwelt upon the nature of dreams as an index of the sound- 

 ness of sleep. If a dream was a connected series of events 

 and was recollected as such after waking, it was clear that 

 the mental rest was impaired. The more coherent and the 

 more realistic the dream, and the more directly it was con- 

 cerned with events in the recent past, the less restful was 

 the sleep in which it occurred. The quality as well as 

 the quantity of the sleep was all-important. 



The sitting of Friday morning, August 3, was devoted 

 to a paper on public health. Dr. George Reid, the 

 medical officer of health for Staffordshire, put forward a 

 number of telling arguments, the result of experiments 

 which he had performed, in favour of changing the form 

 of many sewage filters. It appears that the chemical 

 changes which take place in a filter of fine particles are 

 completed relatively near the surface. Dr. Reid advocates 

 the use of one-eigiith inch particles, and of filters only about 

 4 feet deep. .Such filters would be much less expensive 

 than those now in use. A detailed account of his investi- 

 gations was recently published by the Royal .Society. 



Dr. Hime, of Bradford, brought forward a strong indict- 

 ment of the present system of reporting and isolating in- 

 fectious diseases. His data were collected from twenty- 

 five large towns in the United Kingdom, and dealt with 

 diphtheria, scariatina, and typhoid, which taken together 

 formed 95 per cent, of the cases reported. His general 

 argument w^as that the epidemics of these diseases had 

 increased in virulence and number within recent years in 

 spite of the present system. The most telling figures 

 which he adduced were from cases where the hospitals 

 had been closed to one or other of these complaints and 

 the cases sent back to their homes. On one such occasion 

 more than ninety cases of scarlatina were sent back to the 

 poor neighbourhoods of a town. No epidemic followed ; 

 in fact, the epidemic which was prevalent ceased at once. 



The discussion which followed Dr. Hime's paper turned 

 rather upon a matter of principle. Granted that experts 

 were in doubt concerning the present system of reporting 

 and isolating cases, was it wise to make the matter one 

 of Dublic discussion? Some medical officers held that such 

 debate weakened the trust in the public authority, and 

 introduced an erenienl of personal option as to whether 



