“The results of the experiment demonstrated so great an increase of endurance as to seem at first incredible. It certainly was a surprise, both to the men and to me. But statistics which I have been collecting during the last two years have prepared me to find great differences and changes in endurance. The special result of the present experiment is to show that diet is an important factor in producing such alterations. The fact that endurance, even among persons free from disease, is one of the most variable of human faculties—far more variable than strength, for instance—is evident to any one who has made even a superficial examination. Some persons are tired by climbing a flight of stairs, whereas the Swiss guides, throughout the summer season, day after day spend their entire time in climbing the Matterhorn and other peaks; some persons are “winded” by running a block for a street car, whereas a Chinese coolie will run for hours on end; in mental work, some persons are unable to apply themselves more than an hour at a time, whereas others, like Humboldt, can work almost continuously through eighteen hours of the day. [Illustration: MR. JOHN E. GRANGER BREAKING THE WORLD’S RECORD FOR DEEP KNEE BENDING. The spectator at the extreme right is Mr. Alonzo A. Stagg, coach of the Chicago University football team. Mr. Michael Williams is between the two.] “It is, to say the least, remarkable that hitherto so little effort has been directed toward discovering the factors which explain such differences in endurance. That exercise is one of the most and perhaps the most important factor has long been recognized. A correspondent assures me that by means of moderate _regular_ exercise he succeeded in increasing his endurance between 100 and 200% in three weeks as measured by leg-raising and “dipping.” The influence of diet has always been regarded as small or negligible, and the opinion has almost been universal, until recently, that a diet rich in proteid promotes endurance. Even among those whose researches have led them to the opposite conclusion, there is very little conception of the extent to which diet is correlated with endurance. Such a person, a medical friend of the writer, stated, when the present experiment was planned, that he did not think the dietetic factor strong enough compared with others to produce any marked effect. We have all heard, of course, of the enthusiastic reports of vegetarians as to their increased endurance, but these we have discounted as exaggerations. The result of the present experiment, however, would seem to indicate that one’s improvement in endurance is usually not less, but greater, than he himself is aware of. Probably it is also true that we may lose a large fraction of our working power before we are distinctly conscious of the fact.