Finally, the writer in summing up his own experience is inclined to say that while he entered upon this experiment simply with a view to studying the question from a purely scientific and physiological standpoint, he has become so deeply impressed with the great gain to the body by this practice of physiological economy, and his system has become so accustomed to the new level of nutrition that there is no desire to return to the more liberal dietetic habits of former years.
Obviously, it is not wise nor safe to draw too broad deductions from a single individual, nor from a single experiment even though it extends over a long period of time; consequently, we may turn our attention to other individuals with presumably different personality and different habits of life. The writer’s colleague, Dr. Lafayette B. Mendel, Professor of Physiological Chemistry in the Sheffield Scientific School, kindly volunteered to become a subject of experiment. With a body-weight of 76 kilos, 32 years of age, and of strong physique, he commenced to modify his diet about the middle of October, 1903, diminishing gradually the amount of proteid food with the results shown in the following tables, where are given, as in the preceding experiment, the amounts of nitrogen in the urine, as a measure of the quantity of proteid metabolized, uric acid, and other factors of interest in this connection.
The collection of data commenced on October 26, 1903. During some weeks the urine of each day was not analyzed by itself, but an aliquot part was taken from the 24 hours’ quantity, and at the end of a week the determinations were made on the mixture, thereby giving the average daily composition for the period. With Dr. Mendel, as in the writer’s case, there was no prescribing of food, but perfect freedom of choice. The appetite was satisfied each day, but with a gradual diminution of proteid food, especially of meat. Dr. Mendel appeared to accomplish the desired end best by keeping up a liberal allowance of non-nitrogenous food, and the total potential energy of the daily diet was not so greatly diminished as in the writer’s case. In other words, he appeared to need more food, but succeeded without great effort in reducing the proteid intake to nearly as low a level as in the preceding experiment. For the period of three months from January 4 to April 3, 1904, the average daily excretion of nitrogen amounted to 6.46 grams, which means the metabolism of 40.37 grams of proteid or albuminous food per day for this quarter of the year.
MENDEL.
From November 10, 1903, to June 23, 1904, a period of about seven months and a half, the average daily excretion of nitrogen through the urine was 6.53 grams. In other words, throughout this long period the average daily amount of proteid matter metabolized was 40.8 grams, only a little more than one-third the amount called for by the Voit standard. Until February, the body-weight gradually fell, but from the early part of February until the end of the experiment the body-weight remained practically stationary at 70 kilos. Dr. Mendel, however, from the necessities of his daily work in the laboratory was compelled to a much greater degree of physical activity than the subject of the preceding experiment, and consequently required a larger amount of non-nitrogenous food than the latter. Further, owing to his greater physical activity and the necessary variations in this daily activity, it was not so easy at first to attain equilibrium.
On February 9, a balance experiment of six days was commenced, with a careful comparison of the nitrogen intake and output. In the accompanying tables are shown all of the data. By scrutiny of these it will be seen that Dr. Mendel had adopted essentially a vegetarian diet. During this period of six days, however, he was not in nitrogen equilibrium, neither was he strictly in body equilibrium, since there was a distinct tendency for the body to fall off in weight. In this connection it may be mentioned that there is always a tendency during a balance experiment of this character for the subject to eat less than he is ordinarily accustomed to, owing to the tediousness of weighing every particle of food consumed. Further, for the same reason, and to avoid excess of chemical work in the analysis of samples of food, he is inclined to limit his diet to a few articles and thereby unconsciously restricts his intake of food, sometimes disastrously so.
Tuesday, February 9, 1904.