632 



SCIENCE. 



[N. S. Vol. XXIV. No. 620, 



calories consumed of about 10 per cent., a re- 

 duction of proteids of about 15 per cent., and 

 of flesh foods (meat, fowl, fish and shell fish) 

 of about 40 per cent. During the second half 

 of the experiment the two rules above men- 

 tioned were continued in force but a third 

 was added. This was, when the appetite was 

 uncertain in its choice of foods, to give the 

 benefit of the doubt to the low proteid and 

 non-flesh foods and to foods regarded, pro- 

 visionally, as the most wholesome. This in- 

 fluence of suggestion was never carried how- 

 ever to the point of eating against appetite. 

 This still remained supreme. Suggestion was 

 used merely to settle cases where appetite was 

 not decisive. 



During the second half of the experiment 

 there was a still more pronounced change in 

 the character of the diet. Comparing the diet 

 in June with that in January it was found 

 that the total calories had fallen about 25 per 

 cent., proteid about 40 per cent, and the flesh 

 foods over 80 per cent, or to about one sixth of 

 the original amount. Moreover the proteid 

 had fallen to the level indicated as desirable 

 in the previous experiments of Professor Chit- 

 tenden, which is one and a half calories of 

 proteid per pound of body weight. 



Other physiological changes were noted. 

 There was reduction in the quantity of the 

 excretions and in the putrefactive and fer- 

 mentative properties of the feces. 



The body weights of the men during the first 

 half of the experiment fell on an average of 

 two pounds and in the second half fell further 

 four pounds. Gymnasium tests were made 

 to ascertain the strength and endurance of the 

 men. It was found that their strength had 

 remained practically constant through the ex- 

 periment while their endurance increased dur- 

 ing the first half about fifty per cent, and 

 during the second half by as much more. 

 A marked distinction was drawn between 

 strength and endurance, strength being the 

 utmost force which a muscle can exert once 

 and endurance the number of times that a 

 muscle can perform an exertion which is with- 

 in its strength. Seven endurance tests were 

 used: rising on the toes; deep knee bending; 

 leg raising; raising five-pound dumb bells by 



the triceps; raising successively dumb bells 

 of fifty pounds, twenty-five pounds, ten pounds 

 and five pounds by the biceps; holding the 

 arms horizontal and running. In many of 

 these tests it was found that the will gave 

 out earlier than the muscle; in short, that 

 they were tests of grit, but in others it was 

 found possible to work the muscles up to the 

 point where they refused to contract further. 

 Many precautions were taken to prevent any 

 errors in these comparisons and only those 

 records were used in the final averages in 

 which the men were less tired in January 

 than after the corresponding tests in June or 

 records in which, both in January and June, 

 the muscle was operated up to the point where 

 it refused to contract. Even with all these 

 precautions the improvement in endurance was 

 found to be enormous. For instance, one of 

 the men who in January could not raise a 

 five-pound dumb bell with his triceps beyond 

 the one hundred and eighty-fifth time, in June 

 was able to do so 501 times, and another who 

 could do the leg raising in January 50 times, 

 in June could perform this 105 times ; another 

 who in January could lift the twenty-five- 

 pound dumb bells with the biceps 10 times, 

 in June could do so 27 times. The average 

 improvement from January to June, making 

 every possible allowance, was over 90 per cent. 

 The men were not as stiff and sore after the 

 June as after the January tests, in spite of 

 the fact that they had performed double the 

 amount of work. 



So far as is known, no other than dietetic 

 causes could have produced this result. The 

 men led sedentary lives with less rather than 

 more exercise than previously. They were no 

 more regular in their habits and made no 

 ~effort to live more hygienically except in the 

 matter of diet. The dietetic factors were 

 merely a wide range of choice of wholesome 

 foods well cooked and appetizing, slow eat- 

 ing and obedience to appetite. As to which 

 of these factors was the most important, and 

 as to the manner in which physiologically 

 they affected an improvement in endurance, 

 there is much room for speculation. In the 

 light of other facts it may at least be suspected 



