FOOD INGESTION AND ENERGY TRANSFORMATIONS WITH SPECIAL REFERENCE TO THE STIMULATING EFFECT OF NUTRIENTS BY FRANCIS G. BENEDICT AND THORNE M. CARPENTER PUBLISHED BY THE CARNEGIE INSTITUTION or WASHINGTON WASHINGTON, 1918 CARNEGIE INSTITUTION OF WASHINGTON PUBLICATION No. 261 PRESS OF GIBSON BROTHERS WASHINGTON CONTENTS. PAGE Introduction 7 Previous investigations on metabolism after food 10 Summary of previous investigations 46 Basal metabolism 47 Basal values used in this research 51 Experiments of 24 hours' duration 52 Critique of 24-hour method 53 Discussion of results of fasting and food experiments on the 24-hour basis .... 55 General conclusions regarding use of 24-hour periods 70 Experiments of approximately 8 hours 72 Critique of 8-hour method 72 Discussion of results of 8-hour experiments without food 74 Middletown calorimeter experiments (8-hour basis) 74 General conclusions regarding 8-hour experiments in Middletown 81 Boston calorimeter experiments (8-hour basis) 82 General conclusions regarding 8-hour experiments in Boston 95 Short-period experiments 97 Critique of the short-period method 97 Discussion of results of short-period experiments 98 Experiments with H. L. H 100 Experiments with L. E. E 103 Experiments with J. K. M 106 Experiments with other subjects 109 Conclusions regarding short-period experiments Ill Use of average basal values for comparison 114 General details regarding the research 121 Metabolism during chewing 126 Statistics of experiments 126 Calorimeter experiments 128 Respiration experiments 132 Discussion of results of chewing experiments 137 Ingestion of water 140 Statistics of experiments 141 Calorimeter experiments 142 Respiration experiments 145 Discussion of results of water-drinking experiments 147 Ingestion of coffee 150 Statistics of experiments 150 Calorimeter experiments 152 Respiration experiments 153 Discussion of results of coffee experiments 157 Ingestion of beef tea 159 Statistics of experiments 159 Calorimeter experiments 160 Respiration experiments 165 Discussion of results of beef-tea experiments 169 Ingestion of carbohydrates 171 Calorimeter experiments 173 Statistics of calorimeter experiments 176 Discussion of calorimeter experiments 178 1 2 CONTENTS. PAGE Ingestion of carbohydrates — Calorimeter experiments — (continued). Discussion of calorimeter experiments. — (continued). Sucrose 178 Maltose-dextrose mixture 182 Bananas and sugar 185 Bananas 190 Popcorn 192 Rice 194 General discussion of calorimeter experiments with carbohydrates 194 Maximum effect of carbohydrate ingestion on metabolism (direct calorimetry ) . 195 Total increments in metabolism after carbohydrate ingestion (direct calo- rimetry) 198 Respiration experiments 202 Statistics of respiration experiments 204 Dextrose experiments 205 Levulose experiments 211 Sucrose experiments 215 Lactose experiments 222 General discussion of respiration experiments with carbohydrates 224 Maximum effect on metabolism of carbohydrate ingestion (indirect calo- rimetry) 225 Dextrose 225 Levulose 227 Sucrose. 227 Lactose 229 Comparison of maximum increments obtained with various pure carbo- hydrates 230 Total increment in metabolism after carbohydrate ingestion (indirect calo- rimetry) 232 Dextrose 234 Levulose 235 Sucrose 235 Lactose 236 Comparison of total increments in metabolism obtained with various pure carbohydrates 237 The respiratory quotient after ingestion of carbohydrates 240 Dextrose 240 Levulose 242 Sucrose 243 Lactose 244 Comparison of respiratory quotients obtained with various pure carbo- hydrates 245 General discussion of results obtained with pure carbohydrates 247 Ingestion of fat 251 Statistics of experiments 251 Discussion of experiments 254 Olive oil (mayonnaise) 254 Cream 254 Butter and potato chips 258 Conclusions regarding effect of ingestion of fat 264 Ingestion of predominatingly protein diets 265 Beefsteak 265 Middletown calorimeter experiments 265 Discussion of experiments 266 Boston calorimeter experiments 270 Discussion of experiments 271 CONTENTS. 6 PAGE Ingestion of predominatingly protein diets — (continued). Beefsteak and small amounts of other food materials 275 Beefsteak and bread 275 Discussion of experiments 275 Beefsteak and potato chips 278 Discussion of experiments 279 Respiration experiments with beefsteak 283 Prolonged effect of protein 286 Conclusions as to effect of ingesting beefsteak 287 Glidine 288 Discussion of experiments 289 Conclusions as to effect of ingesting glidine 292 Gluten bread and skim milk 292 Discussion of experiments 293 Conclusions as to effect of ingesting gluten 296 Plasmon and skim milk 297 Summary of results of experiments on ingestion of protein 299 Ingestion of mixed nutrients 306 Milk 306 Calorimeter experiments 306 Respiration experiment 309 Mixed diet 310 Calorimeter experiments 310 Heavy breakfast 313 Heavy supper 318 Respiration experiments 321 Previously published experiments with mixed diets 323 Some relationships between energy output and food intake 328 General quantitative relations 330 Relationship of the fuel value of ingested food to excess heat production 333 Special relations of protein diets to energy transformations 343 Causes of increase in metabolism subsequent to ingestion of food 346 General conclusions 349 Appendix 353 Suggestions as to method for studying the effect upon basal metabolism of ingestion of food or drugs 353 FOOD INGESTION AND ENERGY TRANSFORMATIONS WITH SPECIAL REFERENCE TO THE STIMULATING EFFECT OF NUTRIENTS BY FRANCIS G. BENEDICT AND THORNE M. CARPENTER FOOD INGESTION AND ENERGY TRANSFORMATIONS WITH SPECIAL REFERENCE TO THE STIMU- LATING EFFECT OF NUTRIENTS. INTRODUCTION. During the period of gestation the fetus is supplied with nourish- ment from the mother through the placenta and no muscular movement or exertion of any kind is required to secure food. After birth much of the muscular activity of infants is a direct or indirect effort to secure nourishment. This includes not only the act of suckling but also the muscular activity and crying due to hunger. Thus the apparently anomalous condition exists of an expenditure of a considerable amount of energy for the purpose of obtaining energy for vital processes. With animals of prey there is usually a period of intense muscular activity prior to feeding. The chase, the attack, the act of killing and tearing apart of the prey, all make demands upon the energy supply of the animal. After feeding, there is usually a relatively long period of muscular repose, although, as will be seen later, immediately after eating there is invariably an increase in the internal cellular activity incident to the process of digestion. Even with non-predatory animals and birds a considerable amount of energy is necessary to secure food. The trails to the feeding-grounds, "salt-licks," and watering-places often lead over considerable distances. Birds fly enormous distances to special feeding-grounds, while with birds of prey the chase and attack are comparable to those of animals of prey. An exception to this general activity in securing food is the serpent, which, instead of having to chase its prey, lies in wait for it. When the victim is captured, the serpent kills it either by poison, which of itself requires no muscular activity other than the act of striking, or by con- striction, which usually continues but a short time. Probably no living organism secures its food with so economical a consumption of energy as the serpent does, not only because of its extraordinarily low metab- olism, which permits it to live for a long time without food, but also because of the minimum amount of muscular activity expended in obtaining the food. With the human infant the muscular activity incidental to securing food plays a very important role. To what extent irritation and discomfort, accompanied by vigorous muscular exercise and crying, may be directly charged to a desire for nourishment is problematical, but in any event it is certain that a large part of the physical activity of an infant is due to an effort to secure food. In human civilization it is rarely that an individual must pursue, attack, gather, and prepare his food prior to eating, as the food materials 8 FOOD INGEST I ON AND ENERGY TRANSFORMATIONS. are gathered by harvesters, hunters, or fishermen, brought to the dwelling by transportation agencies, prepared by some member of the household, and finally placed upon the table ready for consumption. With humans the exertion necessary to secure food is no longer indi- vidual, but represents the serious occupation of a large number of persons devoted to this service only. But even after the food has been prepared and placed before the individual, there are certain muscular processes necessary to prepare it for digestion; these are admirably classified by Armsby in the following paragraph: "In the process of digestion we are probably safe in assuming that the muscular work of prehension, mastication, deglutition, rumination, peristalsis, etc., constitutes an important source of heat production."1 Entirely aside from the external muscular activity incident to the pro- curing and preparing of food and its introduction into the mouth, we have internal processes other than those of mastication, primarily the movements of the stomach and intestinal tract, which may be grouped under the general term of peristalsis. These movements, certainly in ruminants, are very considerable in amount. While with humans rumination does not occur, yet the admirable X-ray observations of Cannon2 have demonstrated that with men peristalsis is continuous during digestion. How much the movements of peristalsis and seg- mentation contribute to or make demands upon the energy of the body is a problem still to be considered. The possibility of there being extensive demands for these processes in man has been carefully con- sidered by Zuntz and his co-workers. These investigators have been influenced in large part by their observations on ruminants and herbiv- orous animals in general, such animals having a large amount of residue or ballast in the gastro-intestinal tract that must be worked over by the peristaltic movements. Finally, a considerable demand is made upon the energy of the body for heat to warm the ingesta. Water and many other fluids are com- monly taken by man at a temperature considerably lower than the temperature of the body ; these must be warmed to body-temperature. Again, certain liquids are taken somewhat above the temperature of the body and therefore may contribute, in part at least, to the heat elimination. The amount of cold ingesta required to be warmed by body heat is invariably much greater than the amount of warm food taken, so that in many instances we have carefully to consider this expenditure of heat. In fact, this has been pointed out as an impor- tant path for the output of heat in diabetics with an enormous excretion of urine. If 3 liters of water are taken and excreted as urine in the course of the day, it will be seen that this water may be warmed from 'Armsby, The principles of animal nutrition, 2d ed., 1906, p. 374. 'Cannon, The mechanical factors of digestion, 1911. INTRODUCTION. 9 an average of 10° C. to the temperature of the body, or 37° C., with an expenditure of 81 calories.1 The feeling of warmth following the ingestion of food, familiar to all, is not without significance as being a crude index of a scientific fact which has been well established since the days of Lavoisier and Jurine, i. e., that after food ingestion there is an increase in the metab- olism or heat output. At present the main subjects for discussion with physiologists are not as to there being an increase in the heat output, but first, as to its quantitative relations to the ingesta; second, as to the cause of the increase in the heat output. After an historical examination of the evidence with human sub- jects which has thus far been accumulated to show that there is an increased heat production following food, the results of an extensive series of observations made under the auspices of the Carnegie Institu- tion of Washington, first in the Department of Chemistry of Wesleyan University, Middletown, Connecticut, and later in the Nutrition Laboratory in Boston, will be presented. These observations, cover- ing a period of 10 years, were made with a variety of methods and somewhat changing technique, so that they are not strictly compar- able in all instances. The evidence is, however, so extensive as to throw general light upon the metabolism following ingestion of food and justifies a consideration of the quantitative relations between the energy intake and character of the ingesta and the quantitative increase in the metabolism of man following the ingestion of the various diets. 'Benedict and Joslin, Carnegie Inst. Wash. Pub. No. 136, 1910, p. 230. 10 FOOD INGESTION AND ENERGY TRANSFORMATIONS. PREVIOUS INVESTIGATIONS ON METABOLISM AFTER FOOD. Lavoisier and Seguin, 1789. — The fact that the ingestion of food causes an increase in the metabolism in the body was first made known through the classical researches of Lavoisier and Se'guin.1 As with many phases of physiological chemistry, our first information as to quantitative values for these important body processes is obtained from the remarkable series of experiments carried out by Lavoisier. Judging from incomplete statements appearing intermittently in the writings of Lavoisier and of Se'guin, together with the drawings attrib- uted to Madame Lavoisier, the expired air was collected by means of an air-tight mask attached to the subject's face. It is of interest to note that this method is now the basis of practically all of the modern mine-rescue apparatus and " gas-masks", and is also finding extensive use in clinical laboratories. The statement is made by Lavoisier that a man fasting, or at least with an empty stomach and quiet, consumes in one hour 1,210 cubic pouces of oxygen. This corresponds, according to the table of reduc- tions of Gavarret,2 to 24.002 liters. Lavoisier also states that during digestion the oxygen consumption increases to 1,800 or 1,900 cubic pouces, the latter value corresponding to 37.689 liters. Thus we note an increment of approximately 700 cubic pouces due to taking food or, in other words, somewhat over 50 per cent. The kind of food and the amount eaten were not given. Lavoisier recognized the fact that individuality may play a role here; we cite his criticism: "Nous ne parlons en ce moment que de rapports. On congoit, en effet, que la consommation absolue doit varier conside"rablement dans diffe"rents indi- vidus, suivant leur age, leur 6tat de vigueur et de sant6, suivant qu'ils ont plus ou moins contracte 1'habitude des travaux penibles; mais il n'est pas moins vrai qu'il existe pour chaque personne une loi qui ne se de'ment pas, lorsque les experiences sont faites dans les memes circonstances et a des intervalles de temps peu e'loigne's."3 In studying the literature 130 years after the appearance of Lavoi- sier's first paper, it is surprising to note his clear conceptions of the problems involved both in the muscular work of man and in diges- tion. While an increment in metabolism amounting approximately to over 50 per cent is somewhat higher than that commonly observed and somewhat higher, in all probability, than modern methods would show for the diet of the subject, nevertheless it is by no means an impossibility. We have thus this earliest recorded estimate of the increased energy required to digest a meal. 'Seguin and Lavoisier, Meraoires de 1'Acad. des Sciences, 1789, p. 185; also Oeuvresde Lavoisier. 1862, 2, p. 688. *Gavarret, Physique medicale. De la chaleur produite par les etres vivants. 1S55, p. 330. 3S6guin and Lavoisier, Oeuvres de Lavoisier, 1862, 2, p. 69ft. PREVIOUS INVESTIGATIONS. 11 1789. — Almost simultaneously with Lavoisier's paper we have an interesting communication from Jurine of Geneva. In his researches Jurine employed a Fontana eudiometer, then much used in Europe as the earliest method for analyzing gases, particularly atmospheric air. With this apparatus he studied the influence upon the expired air of various physiological processes, among others those of the ingestion of food.1 The experiments were confined exclusively to determinations of the differences in composition of the expired air. The subject evidently breathed through a glass tube flattened to fit the shape of the mouth, and the expired air was collected at times over water and at times over mercury in a bell-jar. A stopcock was turned at the beginning and end of each expiration. Among other experi- ments, Jurine made three on the influence of food upon the respiratory exchange as shown by the changes in the composition of the air. Both a fasting experiment and a food experiment were made with each of three subjects, a young girl 10 years old, a man 36 years old, and a woman 62 years old. The food experiments were to determine if the increased blood circulation, depending on or incident to digestion, would increase the oxygen consumption. In the air collected over water no change was found in the oxygen content, while in the air collected over mercury a very sensible increase was found in the pro- portion of carbon dioxide present. The total amount of carbon dioxide produced in 24 hours was computed by Jurine from the average number of respirations and from the volume expired per respiration. We find no evidence, however, that he calculated the total increase in the carbon- dioxide production due to digestion. This method of studying the expired air was followed for a number of years by other scientists, little emphasis being placed upon the total quantitative amount of carbon dioxide expired in a given time, but chiefly upon the alteration in the carbon-dioxide content of the expired air. We know now that this change in composition has but little sig- nificance unless accompanied by some knowledge of the total ventila- tion of the lungs, a factor that was entirely overlooked, or at least undetermined, in many of the early researches. Prout, 1813. — One of the most extended observations upon the influ- ence of food on the carbon-dioxide percentage of the expired air is that recorded by Prout.2 The subject, Prout himself, expired into a bladder, regulating the number of expirations to six. A sample of air was then taken in a tube and the carbon dioxide was determined by absorption with strong caustic potash. Prout remarks that as his main object was to discover general laws he did not pay so much attention to the question of the influence of food, although during the three weeks of experimentation he ate only the simplest food and with 'Jurine, Histoire et M6m. Soc. Med., 1789, 10, p. 19. 'Prout, Annals of Philosophy, 1813, 2d ed., 2, p. 328. 12 FOOD INGESTION AND ENERGY TRANSFORMATIONS. as much regularity as possible. The effects from the food, therefore, were not remarkable. Apparently the food taken simply kept the carbon-dioxide production up to the standard and occasionally increased it somewhat, certainly never depressed it. Prout found that fermented liquor, which was occasionally taken, always depressed the carbon- dioxide production. Tea had a like depressing effect, for after 3 or 4 ounces of strong, cold tea he found a considerable diminution in the carbon-dioxide produced. As Prout was much surprised to note the depressing effect of alcohol and all liquors containing it, he made a number of observations on alcoholic liquors, which invariably gave the same result, i. e., a depression of the carbon-dioxide excretion. In this consideration of his results, it is important to bear in mind the fact that his observations were solely on the percentage of carbon dioxide in the air. Little evidence is given in this paper to lead one to think that he had any conception of the total amount of the carbon-dioxide excretion. Scharling,1 in citing Prout's experiments, concludes from the figures given for pulse rate that there really was a greater carbon- dioxide production after the ingestion of food than Prout noted. Fyfe, 1814- — At about the same time as Prout's experiments, a number of observations were made by Andrea Fyfe,2 of Edinburgh, which form the basis of a communication made by Prout in 1814.3 Like Prout, Fyfe dealt exclusively with the percentage of carbon dioxide in the expired air. The expired air was collected in a bell- jar holding approximately 2.5 liters; the proportions of carbon dioxide and oxygen were then determined by means of a Hope eudiometer with the use of lime-water and sulphuret of lime. In an extensive series of experiments in which vegetable diets were given, Fyfe reports that the percentage of carbon dioxide fell from 8.5 per cent before the food experiment to about 4.5 per cent on the seventh and eighth days of the test. The experiments with animal diet lasted 8 days; on the fourth day the carbon dioxide was 7 per cent and on the seventh and eighth days 5 per cent. A repetition of the experiment gave values for the carbon-dioxide content on the third, fourth, fifth, sixth, and seventh days of 6 to 7, 7, 9, 5, and 8 per cent, respectively. When wine was taken, the carbon dioxide in the expired air was reduced in one experiment to between 2 and 3 per cent, and in another to 5.75 per cent. Coathupe, 1839. — Twenty-five years after the experiments of Fyfe, Coathupe4 made a series of observations on the products of respiration at different periods of the day, employing much the same apparatus 'Scharling, Ann. d. Chem. u. Phann., 1843, 45, p. 214. He speaks of Prout's results as being published in the Journ. f. Chem. u. Physik von Schweigger, 1815, 15, p. 65. JFyfe, Dissertatio Chemico-Physiologica Inauguralis de Copia Acidi Carbonic! e Pulmonibus inter respirandum evoluti, 1814. *Prout, Annals of Philosophy, 1814, 4, p. 331. 4Coathupe, Phil. Mag., 1839, 3d ser., 14, p. 401. PREVIOUS INVESTIGATIONS. 13 as that used by Fyfe and Prout. Emphasis was laid solely upon the percentage of carbon dioxide in the expired air. The subject expired into a rubber bag having a capacity of 1,000 cubic inches; samples of air were then taken from this bag, the carbon dioxide being absorbed with lime-water. Experiments were made both before and after food. Coathupe concluded that the carbon dioxide produced in respiration is less during the period of active digestion, that it increases with increased abstinence from food, and that it varies with the same individual at similar periods of different days; excitement of any kind causes a decrease. It is obvious that the researches of Jurine, Prout, Fyfe, and Coathupe, dealing as they do only with the percentage of carbon dioxide in the expired air, contribute but little of value to our knowledge of the actual changes in the total metabolism incidental to the ingestion of food. Until 1843, therefore, the only quantitative data on this subject to be found in the literature are those obtained in the research of Lavoisier and Se*guin, in which it was noted that approximately a 50 per cent increase in the oxygen consumption followed the ingestion of food. Scharling, 1843. — A considerable period of time intervenes between the early experiments of Lavoisier and the next stage of definite evi- dence. For the purpose of making direct determinations of the carbon dioxide produced by man, Scharling1 constructed a large wooden box having a capacity of approximately 1 cubic meter and ventilated by a pump. The expired air was passed over a chain of glass vessels con- taining sulphuric acid, caustic potash, sulphuric acid, and lime-water respectively. The carbon-dioxide content of the air in the chamber was determined at the beginning and the end of the experiment. The periods were usually 1 hour long, although sometimes varying from 90 to 30 minutes; not more than one or two observations were made in 24 hours. The subjects, six in number, were allowed to read, talk, sew, write, etc., so complete muscular repose was not observed. The results given for each subject are the carbon-dioxide production in grams for the individual periods and per 24 hours, the pulse rate before and after meals, the ratio between day and night for the carbon- dioxide production, and the ratio between body mass and the carbon- dioxide production. Although the experimental technique has been criticized by Zuntz,2 who has shown that undoubtedly carbon dioxide escaped absorption, nevertheless the general conclusions obtained by Scharling are not without interest, for he concludes that, other things being equal, man expires more carbon dioxide after he has eaten than when he is without food, and more when he is awake than when he is asleep. He finds that the maximum carbon-dioxide output occurs 'Scharling, Ann. d. Chem. u. Pharm., 1843, 45, p. 214; reprinted in detail in Ann. d. China. et d. Phys., 1843, aer. 3, 8, p. 478. 2Zuntz, Hermann's Handb. d. Physiol., 1882, 4, (2). p. 123. 14 FOOD INGESTION AND ENERGY TRANSFORMATIONS. after the main meal of the day, independent of the hour at which it is taken. Scharling did not overlook the importance of noting the pulse rate, both in the fasting experiments and in those preceding and fol- lowing the ingestion of food. Although his results may now have but little quantitative value, it is of importance to note that Scharling was the first to employ successfully the chamber principle of studying the respiratory exchange. Vierordt, 1845. — The next two contributions to the experimental research on the respiratory exchange as affected by the ingestion of food unfortunately deal with a very imperfect method for both samp- ling and analyzing the expired air. Vierordt,1 in making a very large number of observations on himself, employed a mouthpiece con- sisting of a short tube over which the lips closed. The nostrils were not closed during the experiment, as Vierordt thought it was impossible to breathe simultaneously through nose and mouth during quiet, normal respiration. The expired air was collected in a glass vessel containing 9,200 c.c., which was filled with a solution of common salt. About 1| minutes were required to fill this vessel completely with expired air. Vierordt based his carbon-dioxide measurements on 1-minute periods, making two experiments in an hour. A mixed diet was taken in the food experiments. Of special interest in this connection are the comparisons made by Vierordt between the food experiments and the fasting experiments. On two occasions when he had not eaten since 7 a. m., he obtained values while still fasting at 2 p. m. He compares the average of these two fasting experiments with the average of his experiments made at 2 p. m. just after eating. This comparison is shown in table 1. TABLE 1. — Comparison of results obtained during fast and afterfood (Vierordt). (Values per minute.) Conditions. Pulse rate. Respiration rate. Air expired. Carbon-dioxid e output. Food 78.8 11.22 c.c. 6,162 c.c. 307.36 Fast 62.5 9.5 5,479 258.18 Difference . . . 16.3 1.72 683 49.18 From other experiments made when meals were taken at different times of the day, he concludes that the digestion of the evening meal proceeds with less energy than that of the noon meal. His conclusion is in part borne out by the fact that the pulse after the evening meal did not show the marked rise which was found after the noon meal. Wierordt, Physiologic des Athmens, 1845. PREVIOUS INVESTIGATIONS. 15 Although Vierordt's methods of sampling and analysis seem very crude, we find that Speck, 47 years later, quotes Vierordt as obtaining values not at all unlike those obtained by himself;1 in fact, he confirms Vierordt's observations in that he finds the maximum carbon-dioxide excretion about 1 hour after the meal. Bticker, 1849. — Although Vierordt was on two occasions able to compare directly the values obtained before eating with those obtained immediately after the meal, in the extensive research published by Bocker2 in 1849 no data were obtained for the post-absorptive condi- tion. His experiments, which were carried out with exactly the same technique as that of Vierordt, are very extended and include the inges- tion of sugar, which was taken in portions usually of 1 to 3 ounces, i. e., about 30 to 90 grams. Occasionally it was taken with honey, but usually with water. The method of computation employed by Bocker is somewhat difficult to follow, for while the percentage of carbon dioxide in the expired air found by him is not unlike that commonly found, namely, 3.5 per cent, the absolute amount of carbon dioxide excreted per minute is considerably more than that ordinarily found under like conditions, varying in his own case from 445 to 589 c.c. per minute. These results were obtained by multiplying the actual values found by the factor 2.51. The found values are much more in accordance with those commonly experienced, namely, from 177 to 235 c.c., than those ob- tained by means of the factor. From these imperfect experiments Bocker concludes that after the ingestion of sugar the amount of carbon dioxide produced is decreased in the ratio of 571.35 to 540.58. He records a marked increase in pulse rate after sugar ingestion. In a series of experiments made with coffee he concludes that the taking of coffee decreases both extensively and intensively the respiratory processes. In discussing the pulse rate Bocker states that he does not think there is any necessary connection between the increase or decrease in pulse rate and the increase or decrease in the production of carbon dioxide, nor does he think that the changes in the respiration rate cause a change in the carbon-dioxide production. From a series of experiments on alcohol he concludes that alcohol decreases both intensively and extensively the respiratory processes. Smith, 1859. — Next to the few classical experiments of Lavoisier and Se"guin no early research is more justly and frequently cited than is that of Edward Smith, who published two papers in 1859. In the first paper3 he describes in detail his methods of experimentation. A mask with two valves was used, the inspired air passing through a dry gas- , Physiologie des menschlichen Athmens, 1892, p. 36. 2B6cker, Beitrage zur Heilkunde, 1849, 1. 3Smith, Phil. Trans., 1859, 149, p. 681. 16 FOOD INGESTION AND ENERGY TRANSFORMATIONS. meter, and the expired air passing first through vessels containing sulphuric acid and finally through a strong solution of caustic potash to absorb the carbon dioxide. The amount of carbon dioxide exhaled was found by weighing, the total amount of ventilation being deter- mined from the volume of air passing through the dry gas-meter. In practically all of the experiments the subject was in the sitting position. A large number of tests were made, both without and with food. In most of the food experiments a substantial mixed diet was used. In giving his results, Smith unfortunately expressed the excretion of car- bon dioxide in English grains per minute,1 but a large proportion of the original data has been recomputed by Sonde'n and Tigerstedt to grams per minute,2 and presented in their excellent collection of the literature of early metabolism experiments. The average of the experi- ments made on himself and with three other subjects showed approxi- mately 8.78 grains of carbon dioxide per minute for an 18-hour day with 3 to 4 meals. As the data obtained in the experiments without food gave an average value of 6.64 grains per minute, the increment after food would be 2.14 grains of carbon dioxide per minute, or 32 per cent over the fasting condition. In one observation Smith took 500 grains of arrowroot boiled in water, and found a slight increment over the fasting value. Generally the maximum quantity of carbon dioxide was observed in from 1 to 2 hours after the meal. Since Smith found, in his first paper, that the processes of digestion with a mixed diet increased the metabolism by approximately 33 per cent, he planned the experiments reported in his second article3 for the especial purpose of studying pure food materials. A large number of food materials of all classes were studied. Certain of Smith's conclusions are recorded herewith: "It is evident that foods may be fitly divided into two classes, viz., those which excite certain respiratory changes (excito-respiratory) , and those which do not. The excito-respiratory are nitrogenous foods, milk and its compo- nents, sugars, rum, beer, stout, the cereals, and potato. The non-exciters are starch, fat, certain alcoholic compounds, the volatile elements of wines and spirits, and coffee leaves. "Respiratory excitants have a temporary action; but the action of most of them commences very quickly and attains its maximum within one hour. "The most powerful respiratory excitants are tea and sugar; then coffee, rum, milk, cocoa, ales, and chicory; then casein and gluten, and lastly, gelatin and albumen. The amount of action was not in uniform proportion to their quantity. Compound aliments, as the cereals containing several of these substances, have an action greater than that of any of their elements."4 We can not conclude the discussion of this interesting memoir of Smith's without noting that he recognized at this early stage of research 115.432 grains equal 1 gram. 2Sonden and Tigerstedt, Skand. Arch. f. Physiol., 1895, 6, pp. 101 and 143. 'Smith, Phil. Trans., 1859, 149, p. 715. *Ibid., pp. 738-7.39. PREVIOUS INVESTIGATIONS. 17 some important factors which are considered at the present time as practically indispensable for successful respiration experiments. Thus, he says that there was always a short period of rest before the observa- tions began. He states: "We sat down at least a quarter of an hour before taking the first observa- tion, or that which showed the state of the system before the substance under inquiry was taken, and which was the basal state with which the subsequent effects of the substance were compared, and upon the accuracy of which the truthfulness of the results mainly depended."1 That he recognized the importance of quietness and uniform muscu- lar activity is indicated by the statement: "the same conditions as to posture and quietude being maintained unbroken throughout the whole inquiry." Finally, we may cite one of the conclusions from his first paper : "There is a normal or basal line below which the system does not pass in health and wakefulness, and which is tolerably uniform. It is the same in the complete abstinence from food as at the end of the interval between meals. There is, also, when at rest, a higher point, which the system does not exceed, due to food, and it is the highest after breakfast and tea."2 Ranke, 1861. — The large respiration chamber constructed by Pet- tenkofer and Voit in Munich was apparently used for the first time with man in June 1861, for a series of experiments carried out by Ranke upon himself and published by him.3 In these experiments the subject either fasted or was given an ordinary diet of undetermined nature, a mixed diet of known composition, or an excessive meat diet ; the obser- vations were all made in periods of 24 hours. The values are recorded in table 2. TABLE 2. — Carbon-dioxide production in fasting and food experiments (Ranke). Date. Weight. Character of food. Carbon dioxide per 24 hours. 1861. July 10 kilos. 72 68 Ordinary diet, undetermined grams. 791.1 June 19 73 85 Mixed. Meat, bread, starch, e<*g, water, etc 759.5 June 21 72 87 Fasting. 2 100 c c. water . . 662.9 July 2 71 79 Fasting. No water 663.5 July 24 72.57 N-free diet. Sugar, starch, fat, water 735.2 July 19 72 85 1,832 grams meat 847.5 July 16 74.22 Maximum diet, not determined; much fat, sugar, and starch. 925.6 Ranke's experiments are referred to in a subsequent publication by Pettenkofer and Voit,4 the statement being made that Ranke found in , Phil. Trans., 1859, 149, p. 717. ., p. 712. 'Ranke, Arch. f. Anat, Physiol., 1862, p. 311. 4Pettenkofer and Voit, Ann. der Chem. u. Pharm., 1862-63, Suppbd., 2, p. 53. 18 FOOD INGESTION AND ENERGY TRANSFORMATIONS. hunger 660 grams of carbon dioxide per 24 hours, and with the richest food 860 grams. Although the fasting value given by Pettenkofer and Voit agrees approximately with Ranke's values (see table 2), the maxi- mum value of 860 grams is considerably less than the 925.6 grams reported by Ranke. Using 660 grams as a basal value, it is seen that the ordinary diet and the mixed diet of known composition increased the metabolism approximately 130 and 100 grams — i. e., about 20 per cent — while the rich meat diet increased it nearly 200 grams and the maximum diet approximately 260 grams, or about 33 and 40 per cent respectively. Ranke's experiments are particularly interesting as representing the first 24-hour experiments made with man. They were carried out with the precautions and beautiful technique which characterize all the work done with this large apparatus by Pettenkofer and Voit, and which completely revolutionized knowledge regarding the energy transformations and gaseous metabolism of man. In a later presentation of his earlier work1 Ranke has expressed his values in the terms of calories per 24 hours, giving approximately 2,000 calories for fasting, 2,300 calories for ordinary diet, and 2,800 calories for a rich meat diet. Pettenkofer and Voit, 1866. — A series of 15 experiments, each 24 hours long, and made with the large respiration chamber in Munich, was reported by Pettenkofer and Voit.2 Of 12 rest experiments, 3 were fasting, 4 were with an average diet, 2 with a protein-rich diet, 2 with a protein-free diet, and 1 with the same diet given in the morning and again in the evening. The average carbon-dioxide production per 24 hours during fast, with the subject used in most of the experiments, was 717 grams. With a mixed diet the carbon-dioxide production increased to 928 grams, an increment of 29 per cent. With a protein-rich diet the authors found that the carbon-dioxide excretion increased to 1,020 grams, which is approximately 10 per cent greater than that found with the mixed diet, but 42 per cent above the fasting value. Although the authors discuss the increments in the oxygen consumption, the errors in the method of indirect determination used make their results of questionable value. If no allowance is made for the change in the character of the materials burned under the various conditions of nutri- ment, we may summarize their results by stating that the ingestion of a mixed diet produced an increment in metabolism of about 30 per cent, and with a protein-rich diet resulted in an increment of about 40 per cent. Berg, 1869. — Using an entirely different type of apparatus, Berg3 made a large number of experiments on himself. In these experiments he employed a mouthpiece, absorption vessels, gas-meter, M tiller valves, 'Ranke, Die Ernahrunn des Menschen, lfS76, p. 107. "Pettenkofer and Voit, Zeitschr. f. Biol., 1866, 2, p. 459. 3Berg, Deutsch. Arch. f. klin. Med., 1869, 6, p. 291. PREVIOUS INVESTIGATIONS. 19 and the Pettenkofer method for determining the carbon dioxide. Special emphasis was laid upon voluntary alteration of the type of respiration which, as we know to-day, affects most the values for the carbon-dioxide production. Nevertheless, taking into consideration only his carbon-dioxide measurements, he finds interesting values before and after food which should be noted here. Thus the carbon- dioxide production per 15 minutes, when the respiration rate averaged 15 per minute, was during fasting 8.819 grams; after a rich meal it increased to 9.960 grams, an increment of 1.141 grams, or approxi- mately 12 per cent. An increase was also noted in the pulse rate from 65 beats per minute during fasting to 71 beats per minute after a rich meal. In the average of the experiments with normal uncontrolled respiration rate the value during hunger for the carbon-dioxide pro- duction per 15 minutes was 4.866 grams and after a rich meal 6.613 grams, an increment of 1.747 grams or about 36 per cent. The pulse rate increased from 52.4 to 61.3 per minute. In one interesting series of experiments, the effect of water-drinking was studied. When the respiration rate was adjusted at 15 per minute Berg found practically no increase in the carbon dioxide produced with water as compared with the values found during thirst. A decrease of 3 beats per minute in the pulse rate was observed. With normal uncontrolled respiration the carbon-dioxide production increased from 5.115 to 6.519 grams per 15 minutes after water, an increment of 1.404 grams or approximately 27 per cent; the pulse rate decreased 5.8 pulse beats per minute. The author concludes that when experiments are made hourly from 7 a. m. to midnight the energy of all the respiratory functions increases after meal times. The maximum is observed 2 hours after the morning meal and 3 hours after the afternoon and even- ing meals. These values pertain to the experiments in which the respi- ration rate was controlled. With uncontrolled respiration the maxi- mum values were noted immediately after each meal. It is clear that the artificial regulation of respiration greatly affected the values found by Berg. The results of his experiments are of interest only in sub- stantiating practically all previous work to the effect that the incre- ment due to the ingestion of food may be from 20 to 35 per cent. Speck, 1873. — The possibility for change in the character of the metabolism after the ingestion of food of varying chemical composition, with consequent changes in the carbon-dioxide excretion not at all commensurate with the true changes in energy transformation, led Speck to make an extensive series of observations upon the respiratory exchange in man, in which we find the first basic determinations of oxygen consumption. By analyzing the expired air, which was col- lected in a spirometer, Speck was able to determine the carbon-dioxide increment and the oxygen deficit in the air passing through the lungs. From these values he computed the carbon-dioxide production and the 20 FOOD INGESTION AND ENERGY TRANSFORMATIONS. oxygen consumption per minute. These varied considerably with different conditions of body activity and after the ingestion of food. Speck's several papers appeared between 1865 and 1892, but were brought together and summarized by him in one publication.1 In his earliest communication on the influence of food ingestion2 he observed that the respiratory exchange was increased about 12 per cent by an ordinary mixed diet. In another series, published by him in 1874,3 he reports numerous experiments with food and concludes that the respiratory exchange is increased after the noon meal 25 per cent. This marked increase in heat production, which takes place, he finds, within 30 minutes after a meal, led him to the belief that the work of digestion must cause this increased gaseous metabolism, since it is not to be expected that much food would be absorbed into the blood within the short space of 30 minutes. From the protein experiments4 he concludes that 2 hours after the meal the height of digestion is passed and that at the end of 4 hours digestion is completed. In the sugar experiments he finds that 1 hour after the ingestion of sugar the digestion ceases. In two experiments with coffee he records a small but visible rise in the metabolism. Two experiments were made likewise on the effect of water-drinking and of flooding the body with water for some time before the experiment. According to his results, when the water is taken the evening before and to within an hour of the experiment in the morning there is no influence upon the metabolism; when the water is taken a short time before the experiment, that is, 1,250 c.c. in an hour, and the experiment is made about 30 minutes after the completion of the water- drinking, he notes a marked rise in the gaseous metabolism. Fredericq, 1882.— By using a most ingenious apparatus, called by him an "oxygenographe," Fredericq,5 in the laboratory at Liege, was able to determine the oxygen consumption directly on man both before and after taking food. This apparatus is a modification of an earlier form devised for animals. It is of special interest in that the oxygen is supplied to the apparatus by means of a movable bell floating in a bath of chloride of calcium solution, a principle which underlies the present universal respiration apparatus so extensively used in this and other laboratories. The carbon dioxide is absorbed by a mixture of lime and caustic soda, but the oxygen consumption is the only factor measured. Fredericq concludes that digestion is accompanied by a marked increase in the consumption of oxygen and illustrates this by several interesting curves of oxygen consumption throughout the day which show the relationship of this factor to the time in which food was 'Speck, Physiologic dea menschlichen Athmens, 1892. 2Speck, Tagebl. d. 46 Vers. d. Naturf. u. Aerate in Wiesbaden, 1873, p. 136. 3Speck, Arch. f. exp. Path. u. Pharm., 1X74, 2, p. 405. 4Speck, Physiologic des menschlichen Athmens. 1892. 'Fredericq, Arch, de Biol., 1882, 3, p. 687; Elements de Physiologic Humaine, 2d ed., 1888. PREVIOUS INVESTIGATIONS. 21 taken. In a typical experiment he finds the oxygen consumption can increase from 4.5 liters in 15 minutes (fasting) to a maximum of 6.12 liters after a meal. He lays special emphasis upon glandular activity in the work of digestion, which he thinks accounts for this increase in oxygen consumption. His results agree for the most part with those of current observations, except for showing an extraordinarily rapid return to the basal level folio wing food. Fredericq's conclusions regard- ing digestion represent a very great advance and deserve to be widely quoted at the present time. His article gives one of the best considera- tions of digestive activity ever written. Henrijean, 1883. — Henrijean,1 publishing from Fredericq's labora- tory, and using his apparatus, made a study of the influence of alcohol in nutrition. The experiments were made each morning at the same hour and continued 15 minutes; 5 were fasting experiments, 4 after alcohol, and 3 after food. In the food experiments bread varying in amount from 120 to 190 grams was given. The results are expressed as oxygen consumed in 15 minutes, reduced to standard conditions of temperature and pressure. Thus during fast the oxygen consumption was 3.5 liters, with alcohol 4.17 liters, and with bread 4.35 liters. From these data Henrijean concludes that the amount of oxygen consumed after alcohol or food in general is always greater than that when fasting ; the increment after bread is approximately 25 per cent ; after alcohol it is a little less. Jolyet, Bergonie, and Sigalas, 1887. — Using a new respiration appa- ratus on a closed-circuit plan, in which the subject breathes through a hermetically sealed mask, Jolyet, Bergonie, and Sigalas2 report two series of experiments which have a slight bearing upon the question of the influence of food. Thus, as an average of 7 experiments with the subject fasting and at rest, they found the oxygen consumption per kilogram per hour was 259 c.c. In 7 experiments with food (neither the kinds nor the amounts of food are stated) the oxygen consumption was 275 c.c. per kilogram per hour. Apparently no further experi- ments were made on this problem with the apparatus. Lehmann, Mueller, Munk, Senator, and Zuntz, 1887-1893. — The first use of the Zuntz-Geppert respiration apparatus for studying the me- tabolism of man was in the series of observations made on the fasting subjects, Cetti and Breithaupt.3 The study made with Cetti in March, 1887, was reported in brief by Senator and his collaborators.4 This con- sisted of a fasting period of 10 days, followed by 3 days with food. The •Henrijean, Bulletin 1'Acad. Roy. de Belgique, 1883, ser. 3, 5, p. 113. 2Jolyet, Bergoni?, and Sigalas, Compt. rend., 1887, 105, pp. 380 and 675. 3Although the essentials of the Zuntz-Geppert apparatus were described by Zuntz and his asso- ciates (Lehmann, Mueller, Munk, Senator, and Zuntz., Arch. f. path. Anat. u. Physiol., 1893, 131, Supp., p. 1), the best description of the apparatus was that given later by Magnus-Levy, Arch. f. d. ges. Physiol., 1894, 55, p. 1. ^Senator, Berl. klin. Wochenschr., 1887, Nr. 16, p. 290; Nr. 24, p. 425; see especially report by Zuntz and Lehmann, p. 428. 22 FOOD INGESTION AND ENERGY TRANSFORMATIONS. increment due to the ingestion of food was clearly shown, the authors remarking that the first meal increased the size of the combustion as a result of the stimulation to the work of digestion. One year later a second study of the metabolism during fasting was made with Breit- haupt, and an extended report of the fasting experiments with both subjects was published cooperatively by Lehmann, Mueller, Munk, Senator, and Zuntz.1 In their general consideration of the experiments on food they state: "Im Beginn der Wiederernahrung nach langerem Hungern wachst der Stoffwechsel in Folge der Verdauungsarbeit. Nachdem diese beendet, etwa 12 Stunden nach der letzten Mahlzeit beobachtet man niedrigere Sauerstoff- zahlen als im Hunger. Der calorische Werth des Umsatzes ist aber eher hoher, weil die Kohlenhydrate bei gleichem Sauerstoffverbrauch mehr Warme entwickeln als Fett und Eiweiss."2 In the study with Breithaupt, in which the results obtained were more comparable than those with Cetti, the average total heat produc- tion for the two days of food before the fasting was 1,645 calories per 24 hours. The average of the 6 fasting days was 1,550 calories per 24 hours, the average of the fifth and sixth fasting days being 1,292 calories per 24 hours. In the 2 days with food after fasting the metabo- lism increased to 1,453 calories. The average heat production for two days with food, even when computed on the basis of per kilogram of body-weight, was slightly above that for the last 2 days of fasting, but not so large as the average for the 6 fasting days. It should be stated, however, that the total amount is computed from observa- tions of relatively short duration. Sadovyen, 1887-1888. — Sadovyen,3 using the Pashutin respiration apparatus in St. Petersburg, made a series of food experiments before and after fasting with one subject, a man 28 years old, with a body- weight of 79 kilograms. Since the method employed was unique and the place of publication obscure, the values are abstracted in table 3. Sadovyen concludes that there is usually a slight decrease in the carbon-dioxide output during fasting and that this decrease is in pro- portion to the duration of fasting. His data also lead him to believe that there is no great difference between the oxygen absorbed during fasting and after food, although the general decrease in the amount of oxygen absorbed during fasting can be considered as having been estab- lished. As is to be expected, the carbon-dioxide excretion was the greatest after carbohydrates, this increase being roughly proportional to the amount of carbohydrate taken. The carbon-dioxide figures, 'Lehmann, Mueller, Munk, Senator, and Zuntz, Arch. f. path. Anat. u. Physiol., 1893, 131, Supp., p. 1. *Ibid., p. 215. 'Sadovyen, Pub. Russian Soc. Gen. Hyg., 1887-88, 12. PREVIOUS INVESTIGATIONS. 23 therefore, show very sharply the increment due to food, but the oxygen values appear to be practically unaffected by this factor. TABLE 3. — Respiratory exchange in food and fasting experiments (Sadovyen). Per kilogram per 24 hours. Character of experiment. Carbon dioxide. Oxygen (computed). First experiment: First day Mixed diet gm. 11.9 am. 9.5 13.6 Third dav Same 9.6 13.0 Mixed diet 14.4 13.6 Second experiment: First day . . . Incomplete fast; a little tea, sugar, bread, 10.1 9.3 water. Fast with water only 10.1 11.7 Third day Same. 8.0 9.0 Same 8.0 12.3 Fifth dav Mixed diet 11.26 10.50 Third experiment: First day Sugar and starch, amount unknown 12.1 Second day Third day Sugar, starch, water; 73 grams starch, 453 grams sugar. Same, 115 grams starch, 352 grams sugar. 13.4 11.5 10.8 9.6 Hanriot and Richet, 1888. — Hanriot and Richet1 published a series of observations upon the metabolism of a man before and after he had taken various foods. The apparatus used by them is in principle much simpler than any thus far devised, but unfortunately, owing to certain technical difficulties, it does not meet modern demands for accuracy. In a series of experiments from March 15 to April 1 with this subject, who weighed 50 kilograms, a mixed diet was given, con- sisting of bread, potatoes, beef, cheese, butter, sugar, wine, coffee, and water. The day's diet contained 268.9 grams of carbon and 20.2 grams of nitrogen. In a following series of experiments the food, somewhat less abundant, contained 230 grams of carbon. During the experiments the subject was seated and awake, but no particular attention was paid to muscular repose. The average values obtained showed that he consumed 17.5 liters of oxygen per hour fasting and 18.9 liters of oxygen per hour 1 to 5 hours after food had been consumed. The observers note that the maximum activity of the respiratory exchange occurred 3 to 4 hours after a mixed diet. In the second paper2 Hanriot and Richet give the results of another study of the gaseous metabolism of this man. In a 2-day fast they found that the respiratory exchange did not alter from the seventeenth to the forty-sixth hours — in other words, a base-line was reached. and Richet, Compt. rend., 1888, 106, p. 419. *Ibid., p. 496. 24 FOOD INGBSTION AND ENERGY TRANSFORMATIONS. Experiments were made with the subject fasting, with 500 grams of roast beef twice per day, with a large amount of potatoes, with glucose, and with fat (lard) and egg yolks. They conclude from this series of experiments that protein and fat modify the respiratory exchange but very little; starchy foods increase the lung ventilation and the absorp- tion of oxygen, and especially the production of carbon dioxide. Their results show that with man during fasting there is a production per kilogram per hour of 0.5 gram of carbon dioxide and an absorption of 0.45 gram of oxygen, and that during digestion the production of carbon dioxide increases to 0.6 gram and the oxygen absorption to 0.50 gram, an increment of approximately 10 per cent. Loewy, 1S88. — In a series of experiments made by Loewy1 in Zuntz's laboratory and primarily designed to study the influence of unoxi- dizable material (Glauber salts) in the intestinal tract, two experiments were made with water. In one it was found that 11 minutes after the subject had taken 100 grams of water the oxygen consumption in- creased from 218.5 c.c. to 221.8 c.c. per minute, an immaterial increase. Later (33 minutes after drinking the water) the oxygen consumption had increased to 232.2 c.c. — i. e., an increment of 14 c.c. of oxygen, or approximately 6 per cent. In another experiment, 10 minutes after taking 100 grams of water, the oxygen consumption increased from a basal value of 221 c.c. per minute to 226 c.c. per minute, an increment of only 5 c.c. of oxygen. Approximately half an hour later the oxygen consumption had increased to 242 c.c. per minute. Since no graphic record of the activity accompanied these experiments- an omission which has been criticized2 — it is difficult to state with certainty whether or not the ingestion of water actually produced a measurable increase in the metabolism. Marcel, 1889. — Marcet3 reported the results of a series of experiments with two subjects, which were designed primarily for a study of the influence of food. The general conclusions confirm the results of previous observations on the influence of food upon the carbon-dioxide production, namely, that the maximum amount occurs between 2 and 3 hours after the meal and the minimum amount just before breakfast. Marcet, 1891. — Later, Marcet4 published the results of a series of experiments on himself and his assistant, Russell, in which 6 experi- ments were made on each subject, about 2 hours after food, and 6 experiments during "fast," i. e., 4 hours after breakfast. Each experi- ment lasted 7 to 8 minutes. The subject, reclining in a steamer chair, inhaled through the nose and exhaled through the mouth, sometimes closing the nostrils with the fingers when necessary. The expired air 'Loewy, Arch. f. d. ges. Physiol., 1888, 43, p. 515. ^Benedict and Emmes, Am. Journ. Physiol., 1912, 30, p. 197. :(Marcet, Proc. Roy. Soc., 1889, 46, p. 340; also, Phil. Trans., 1890, 181, ser. B, p. 1. *]}>;s., 1909, 86, p. 116. 38 FOOD INGESTION AND ENERGY TRANSFORMATIONS. put increased after the same amount of sugar from a basal value of 1.257 calories per minute to a maximum of 1.463 calories in the first hour after feeding. In the fourth hour the basal values were again reached. The respiratory quotients did not exceed unity in any case. Gigon, 1909. — An important contribution from the Stockholm labor- atory on the influence of protein and carbohydrate ingestion upon metabolism was published by Gigon1 in 1909. Since it is well estab- lished that both sugar and protein cause an increase in the carbon-diox- ide production, the experiments were especially designed to study the influence of a combination of sugar and protein. As was usual with the experiments in the Stockholm laboratory, the carbon-dioxide excretion alone was determined. The fasting value was found to be 23.8 grams carbon dioxide per hour. After 46 grams of dextrose this increased to 29.9 grams, and in experiments with 16 grams casein it increased to 28 grams. When these same amounts of dextrose and casein were given together, the carbon dioxide rose to 34 grams. Since the increase in the carbon-dioxide production in the last series of experi- ments was practically the sum of the increments noted in the dextrose and casein experiments, the author concludes that there is a summation effect. Furthermore, if carbohydrate or protein is taken in several equal amounts at regular intervals, the increased carbon-dioxide pro- duction remains at an unchanged height for several hours. The author concludes with an interesting discussion of the Verdauungsarbeit and the specific dynamic action theories, defending the latter. Gigon, 1911. — The most extended discussion of the influence of food on the metabolism of man since the research of Magnus-Levy was contributed by Gigon in 191 1.2 His research, which was carried out with himself as the only subject, and exclusively with pure food mate- rials, was made in part with the Sonde*n-Tigerstedt respiration chamber in Stockholm, and in part with the Jaquet respiration chamber in the Medical Clinic in Basel. A few basal metabolism experiments,3 but no food experiments, were made with a respiration apparatus employing the mouthpiece, Miiller valves, and spirometer in the Poliklinik in Basel. Unfortunately, as has been frequently pointed out, the Stockholm experiments do not include determinations of the oxygen consumption. This deficiency in experimental methods is of special significance in considering the question of carbohydrate ingestion; it likewise renders problematical the calculations and assumptions made by Gigon with regard to the character of the katabolism both during the fasting period and after food. 'Gigon, Skand. Arch. f. Physiol., 1908-09. 21, p. 351. *Gigon, Munchen. med. Wochenschr., 1911, 58, p. 1343; and Arch. f. d. ges. Physiol., 1911, 140, p. 509. See Gigon, Munchen. med. Wochenachr., 1911, 58, p. 1343. PREVIOUS INVESTIGATIONS. 39 Gigon's main contention is that the basal resting metabolism is extraordinarily constant with the same individual over long periods of time. What is even more striking, he claims that the character of the katabolism as apportioned between protein, fat, and carbohydrate is also constant. Most of the experiments in Basel were made during sleep. Gigon concludes that the gas exchange in sleep is perfectly comparable to that "bei vorsdtzlicher Muskelruhe." For the Basel average nuchtern values he uses for the energy output 22.5 calories per kilogram per 24 hours, for the carbon-dioxide excretion 23.356 grams per hour, and for the oxygen consumption 21.05 grams per hour. In the protein experiments made in Stockholm, casein was used, hourly doses of 15.56 grams of this food material increasing the carbon- dioxide excretion 4.2 grams per hour (the Stockholm nuchtern value of 23.8 grams being used as the basal value). In Basel, with the Jaquet apparatus, the casein was given in 50-gram portions, resulting in an average increase of 5.03 grams carbon dioxide (6.1 per cent) for a period of approximately 3| hours. Subsequently 100, 150, and indeed 200 grams casein were given ; in all instances very considerable increases not only of carbon dioxide but of oxygen were noted. The increment for the carbon-dioxide excretion was 15.5, 22, and 26 per cent of the nuchtern value, following 100, 150, and 200 grams of casein respectively. For the oxygen production, 50 grams casein gave 7.4 per cent increase, 100 grams gave 14 per cent, 150 grams gave 22.1 per cent, and 200 grams gave 27.1 per cent increase. Thus when the size of the portion was varied in the ratio of 1 : 2 : 3 : 4, the carbon-dioxide production increased in the ratio of 1 : 4 : 8 : 12 and the oxygen intake increased in the ratio of 1 : 3 : 6 : 9. It should be pointed out that the experi- ments varied considerably in length and hence a comparison of the various amounts of protein is somewhat uncertain. Gigon contends that the combustion of fat and carbohydrate remains unchanged from the nuchtern value when casein is taken. In the Stockholm sugar experiments 46 grams of sugar per hour were given, this amount producing an increase of 6.1 grams per hour in the carbon-dioxide production. On the assumption that the carbon- dioxide excretion can be taken as an index of the metabolism during the dextrose experiments, Gigon computes a metabolism of about 90 calories per hour or about 20 calories above the normal. In Basel two experiments were made, one with 100 and one with 50 grams of sugar, the 100 grams giving twice as great an increase in the carbon-dioxide production as the 50 grams. In the 2-hour experiments in which 50 grams of dextrose were taken the total heat production was 156 cal- ories, or 6 calories per hour above the nuchtern value. In a 4|-hour experiment with 100 grams dextrose an increase of 30 calories over the nuchtern value was found, or approximately 6 to 7 calories per hour. In support of his contention that the basal metabolism is unaffected by 40 FOOD IXGESTION AND ENERGY TRANSFORMATIONS. the ingestion of food, Gigon points out that in the glucose experiments the course of the nitrogen and the phosphoric-pentoxide excretion is practically uninfluenced by dextrose. His observations on the ingestion of fat are of special significance, for at least 2 experiments with 50 grams of olive oil showed a distinct depression of the basal metabolism. With 150 grams of oil the metab- olism was slightly above the basal value. Contrary to the experience in most laboratories, with a change to a fat diet Gigon noted that there was a decrease in the nitrogen excretion in the urine. This depression of the metabolism is explained by Gigon as being due to the fact that even during fasting there is always a certain amount of Verdauungsar- beit, and that the ingestion of oil depresses this, thus affecting the basal value. A careful theoretical discussion is given of the two prevailing views regarding the cause for the increased heat production after food, namely, the Verdauungsarbeit theory of Zuntz and the specific dynamic action theory of Rubner. In discussing the carbohydrate ingestion, Gigon points out that his experiments usually show that there is no increase in the respiratory quotient and that the increase in the gaseous exchange noted must be due to a cause other than an increased combustion of sugar; in most of Gigon's experiments there is little basis for the theory of fat formation from sugar. In discussing the increase following protein disintegra- tion, Gigon concludes that the total protein disintegration does not exceed that of the nuchtern value, and that in all probability there is considerable fat formation from protein, together with a small carbo- hydrate formation. Finally, following the general contention of Johansson, Gigon main- tains that the food is first deposited in the body in different depots, which, in turn, furnish the energy for cellular activity. Since these depots must in large part rely upon fat formation, Gigon points out that there is probably a considerable fat formation and that fat plays a larger role in the metabolism than has heretofore been supposed. Holly and Undeutsch, 1911-13. — Employing the universal respiration apparatus devised in the Nutrition Laboratory, although in a modified and unnecessarily complicated form, Roily and his associate Undeutsch made several normal experiments with women in connection with some of their work in pathology. In reporting the results of 1 basal experi- ment and 3 food experiments, Roily1 discusses the respiratory quotient and attempts to explain what he considers to be a very noticeable rise. It is a fundamental error to lay much stress, as Roily has done, upon a single previously determined basal value. Furthermore, contrary to Rolly's opinion, a nuchtern quotient of 0.819 is not high, as experiments with 68 women in the Nutrition Laboratory gave an average respira- tory quotient of 0.81. In common with the findings of other experi- 'Rolly, Deutseh. Arch. f. klin. Med., 1911-12, 105, p. 494. PREVIOUS INVESTIGATIONS. 41 menters, Roily found that the oxygen consumption was increased by the ingestion of 200 grams of flesh or with protein in other forms. A far better presentation of this material is given in the dissertation of Undeutsch,1 who concludes that the vegetable protein preparations cause a greater increase in the total metabolism than the animal protein does. The maximum increase in the metabolism was reached in 1 to 2 hours after the ingestion of the protein. The effect of the protein disappeared at the end of 6 hours. Amur, 1912. — Employing a Chauveau apparatus with Tissot spirom- eters, Amar2 studied the influence of both carbohydrate and protein diets upon metabolism. Two subjects were used. The carbohydrate meal consisted of rice, potato, and bananas, and corresponded to 95.5 grams of carbohydrate. The protein meal consisted of lean meat and eggs; bread and cheese were also added for one of the subjects. The diets corresponded to 80 and 100 grams of protein respectively. In the carbohydrate experiments the oxygen consumption after a meal increased at first, reaching the maximum in 1 hour, then fell off hour by hour. The respiratory quotient increased hour by hour, although it never reached unity. After protein the oxygen consumption immedi- ately increased, this increase reaching its maximum in 2 hours. The carbohydrates caused an average increase in the oxygen consumption of 6 per cent and the protein an average increase of 11 per cent for a period of 3 hours. Hari and von Pesthy, 1912. — A series of experiments carried out by Hari and von Pesthy,3 with the usual skill of the Budapest laboratories, was made on three subjects with the Zuntz-Geppert apparatus. The primary object was to study the influence of the temperature of the food on the gas exchange. Nuchtern experiments were made first every morning, which were followed by observations after the ingestion of milk. One liter of milk was taken inside of 3 to 4 minutes in one series of 12 experiments at a temperature of 3° to 4° C., and in a second series of 10 experiments at a temperature of 50° to 55° C. The conclu- sions of the authors bearing on this discussion are that both cold and warm milk increase the oxygen consumption about 13 to 15 per cent for 3 hours after the ingestion of milk. With warm milk this increase ceases shortly after 3 hours, but persists several hours more or less unchanged with cold milk. The authors conclude that the longer effect in the latter case may be due to a slower digestion of cold milk. Loeffler, 1912. — Loeffler,4 working under the direction of Gigon in the Poliklinik in Basel, made a study of basal metabolism and likewise 'Undeutsch, Experimentelle Gaswechseluntersuchungen bei Morbus basedowii: Grundumsai « und Umsatz nach Aufnahme von animalischem und vegetabilischem Eiweiss. Inaug.-DiBS., Leipsic, 1913. 5Amar, Journ. de Physiol. et de Path, gen., 1912, 14, p. 298. 3Hari and von Pesthy, Biochem. Zeitschr., 1912, 44, p. 6. 'Loeffler, Arch. f. d. ges. Physiol.. 1912, 147, p. 197. 42 FOOD INGESTION AND ENERGY TRANSFORMATIONS. of the metabolism after the ingestion of 50 grams each of an animal protein (casein) and of a vegetable protein (edestin). For most of his experiments he used the respiration apparatus installed by Gigon, consisting of a spirometer and Miiller water-valves. He concludes that the basal metabolism remained constant for more than four years, and that the results obtained with this apparatus agree perfectly with those obtained with the Jaquet and Sonde"n-Tigerstedt apparatus. Following the ingestion of 50 grams of casein the carbon dioxide in- creased about 5 grams and the oxygen about 5 grams within a period of 3 to 3| hours. A similar increase was noted with edestin. Follow- ing the lines of reasoning developed by Gigon, the author discusses the question of Verdauungsarbeit. He maintains that it exists even in the post-absorptive condition and that therefore this activity is included in the determination of the basal value. He further believes that the increase found by him after the ingestion of protein is due to further changes in the foodstuff after its absorption. Zuntz and Schirokich, 1912. — In a series of experiments with one subject living on a protein-poor diet, Zuntz and Schirokich1 studied the metabolism in the nuchtern condition as well as after food and found the increment in the heat output in the food experiments to be approxi- mately 15 per cent. Gigon, 1912. — In an attempt to study the influence of spices and of flavoring materials upon nutrition, Gigon2 employed the Jaquet respiration apparatus in Basel and made experiments on himself during the night, usually during sleep. Casein in varying amounts was taken with about 1 liter of water. In some of the experiments, 10 grams of salt and 1 gram of pepper were taken with the casein. The increase in the carbon-dioxide production was greater when casein alone was ingested, but the increase was of longer duration when the salt and pepper were added. Gigon notes that the spices had more of an effect on the carbon-dioxide production than they did on the oxygen con- sumption. This influence was more marked with 50 grams casein than with the larger amounts. In his earlier experiments, in which he specially emphasizes the importance of giving pure food materials in contrast to food materials of mixed composition, such as beefsteak, roasts, etc., Gigon found a more rapid return to the basal value than others have found and he now explains the delayed effect of eating other than pure food materials as being due to the influence of the flavors. McCrudden and Lusk, 1912-13. — McCrudden and Lusk,3 in a study of a dwarf 17 years old, with a body- weight of 21 kilograms, found that the basal metabolism in the Cornell calorimeter was increased 6.6 per cent after the ingestion of small quantities of food. This average 'Zuntz and Schirokich, Separate from Med. Klinik, 1912, No. 32, 5 pp. 2Gigon, Verhandl. deut.srh. Kon^r. f. inn. Med., XXIX Kongress, 1912. 'McCrudden and Lusk, Jouru. Biol. Chora., 1912-13, 13, p. 447. PREVIOUS INVESTIGATIONS. 43 figure was obtained from the results of 4 experiments in which the metabolism was observed after a meal of carbohydrate and fat, another of lean meat, and two breakfasts, presumably with mixed diet. Togel, Brezina, and Durig, 1913. — In connection with a study on the effect of alcohol upon the conservation of carbohydrate combus- tion, Togel, Brezina, and Durig1 report several experiments with both levulose and dextrose. The Zuntz-Geppert technique with all of the Durig refinements was employed. Contrary to their usual custom, they determined the base-line in only one period before each sugar experiment. The subject usually received 100 grams of sugar, but in one experiment 3 doses each of 30 grams of levulose were given at 1-hour intervals. After 100 grams of dextrose the respiratory quotients rose at the end of 2 hours to unity or over. With this subject, who had at that time a high carbohydrate storage, the effect of sugar ingestion was not noticeable after about 4 hours. Of special signifi- cance is the fact that even when the subject was in a glycogen-poor condition the typical rise in the curve of the respiratory quotient was not delayed and there was likewise a marked rise in the metabolism, a result somewhat at variance with some of the earlier work. Doses of 100 grams of levulose produced greater increases than the same amounts of dextrose. Although the authors note that the total excess heat produced after giving levulose is greater than that with dextrose, it is worthy of note that the maximum increment in the heat output was essentially the same with both sugars. Schopp, 1913. — Schopp,2 working with Grafe in the Medical Clinic in Heidelberg, in giving a report of rectal feeding experiments, includes a series of 3 nuchtern and 2 food experiments upon himself in which special patented foods were taken per os. These experiments, which were about 10 hours in length, were made with the Grafe respiration chamber and with the subject in the post-absorptive condition at the beginning of the experiment. In the food experiments Schopp found large increases in the heat production of 46 and 33 per cent, respectively. He noted the maximum combustion in the seventh hour, which he is inclined to think was due to toxic peculiarities of the cleavage products of the protein preparations. The conservatism shown in the conclu- sions drawn from his two experiments may well be copied by all writers on metabolism in discussing fragmentary data. Grafe, 1913. — Grafe,3 using his admirable model of the Jaquet appa- ratus in the Heidelberg clinic for observations on a professional fasting woman, noted that the basal metabolism during fast was 1,180 calories per day or 25 calories per kilogram of body-weight. In the first food experiment after the ingestion of 397 grams carbohydrate and 60 grams l, Brezina, and Durig, Biochem. Zeitschr., 1913, 50, p. 296. 'Schopp, Deutsch. Arch. f. klin. Med., 1913, 110, p. 284. 'Grafe, Deutsch. Arch. f. klin. Med., 1913-14, 113, p. 1. 44 FOOD INGESTION AND ENERGY TRANSFORMATIONS. alcohol, the total calorific value of which was 770 calories greater than the basal value, the heat production fell off slightly in 20£ hours. Grafe points out that this rinding agrees with that of Johansson,1 who observed no increase in the metabolism following the ingestion of carbohydrate by a fasting individual, i. e., an individual with low glycogen storage. In a second respiration experiment, in which the subject took 278 grams of carbohydrate, 120 grams of fat, and 30 grams of alcohol, with a total energy content of about 2,180 calories, the increase in the combustion in 20f hours was very small compared with the fasting value, being only 4 per cent. Thus both experiments indicate an extraordinarily small increase in the heat production follow- ing the ingestion of non-protein food after fasting. Rowland, 1913. — In studying the addition of nutrose to the ordinary diet in the case of infants, Rowland2 found with the Cornell calorimeter an increase in the heat production per square meter per day of 10 per cent in one case and 26 per cent in another. Although the basal values without food were not obtained, the increment due to the ingestion of the highly nitrogenous nutrose over that with ordinary food is of sig- nificance in this connection. Bergmark, 1914-15. — Bergmark,3 investigating rectal feeding, reports 4 experiments in which 100 grams and 50 grams of dextrose, respec- tively, were taken per os, the author being the subject. The experi- ments were made in Johansson's laboratory in Stockholm and with the usual Johansson technique. After 100 grams of dextrose, Bergmark found a rise in the carbon-dioxide production of 14.94 grams in 6 hours and 7.02 grams in the same length of time after 50 grams of dextrose. The character of the katabolism was not shown, as the measurements of the metabolism were based only upon the data for the carbon-dioxide production. The agreement with Johansson's earlier results, however, is proof of the uniformity of technique. Bergonie, 1915. — Bergonie,4 without reporting any experimental evidence of his own, calculated the increment in energy output due to the ingestion of three meals a day with a normal individual as being equivalent to 200 calories. Gephart and Du Bois, 1915. — Du Bois, in carrying out the extended series of researches with the respiration calorimeter in the Russell Sage Institute of Pathology, an apparatus designed especially for the study of pathological cases, decided to include the determination of the basal metabolism of normal men and the effect of food. With Gephart5 he reports the results of experiments with 7 men with and without food. The basal experiments were made 14 to 18 hours after food. As a 'Johansson, Skand. Arch. f. Physiol., 1908, 21, p. 1. 2Howland, Trans. 15th Internat. Cong. Hyg. and Demogr., 1913, 2, sect. 2, p. 438. 3Bergmark, Skand. Arch. f. Physiol., 1914-15, 32, p. 355. 4Bergoni6, Rev. Sci. (Paris), 1915, 53, p. 138. 'Gephart and Du Boia, Arch. Intern. Med., 1915, 15, p. 835. PREVIOUS INVESTIGATIONS. 45 basal value the authors used 34.7 calories1 per square meter per hour as the average heat production of fasting normal men between 20 and 50 years of age. After giving 200 grams of dextrose or its equivalent in commercial glucose on 2 days subsequent to the fasting experiments, it was found that this amount caused an average increase of 12.5 per cent in the heat production during the first 3 to 6 hours and that 100 grams caused an average increase of 9 per cent. A casein meal, with 10.5 grams nitrogen, increased the metabolism 12 per cent, and 725 grams of beef, with almost 24 grams of nitrogen, increased it 22 per cent. Gephart and Du Bois, 1916. — In a continuation of the calorimeter experiments at the Russell Sage Institute of Pathology, Gephart and Du Bois2 report 3 experiments with one subject, 1 experiment after 79 grams of olive oil, and 2 experiments after 115 grams of commercial glucose. The basal value for these determinations was obtained 2 days after the 3 experiments were completed. The authors state that their subject "1 to 4 hours after 115 grams of commercial glucose (the equiv- alent of 100 grams dextrose) showed an average metabolism 11 per cent higher than the basal determination two days later." Little increase in the metabolism was noted after the 79 grams of olive oil. Kopciowski, 1916. — Using the somewhat cumbersome Biirgi appara- tus, which was designed primarily for experiments during walking, Kopciowski3 measured the metabolism on himself in 10-minute experi- ments before and after food in both the lying and sitting positions; only the carbon-dioxide production was determined. In 13 experi- ments without food, with the subject in the lying position, he found the average carbon-dioxide production to be 4.557 grams per 10 min- utes; after dinner this increased 17 per cent. In 4 experiments with- out food, with the subject in the sitting position, the carbon-dioxide production was 4.687 grams per 10 minutes; in 17 experiments after breakfast or dinner this was increased to an average of 5.248 grams of carbon dioxide, or an increase of 12 per cent. Without oxygen meas- urements it is obvious that no corrections can be made for alterations in the character of the katabolism. Aub and Du Bois, 1917. — A significant series of experiments on dwarfs and legless men with the Russell Sage calorimeter was made by Aub and Du Bois4 to study the so-called specific dynamic action of protein. The subjects were given a meal of 660 grams of lean beefsteak containing approximately 23 to 25 grams of nitrogen. The investiga- tors laid special emphasis upon the excretion of sulphur. They state that the increase in metabolism following the meat diet was larger for a the Meeh formula. Subsequently the Du Bois linear formula increased this value. 'Gephart and Du Bois, Arch. Intern. Med., 1916, 17, p. 902; Cornell Univ. Med. Bull.. 1917. 6, p. 48. 3Kopciowski, Arch. f. d. ges. Physiol., 1916, 163, p. 247. 4Aub and Du Bois, Arch. Intern. Med., 1917, 19, p. 840. 46 FOOD INGESTJON AND ENERGY TRANSFORMATIONS. legless man and for an achondroplastic dwarf with very small arms and legs and normal trunk than for three normal controls of greater weight and greater surface area. They accordingly conclude that the inten- sity of the specific dynamic action is not proportional to the mass of the musculature, and suggest that it may be due to a greater concen- tration of amino-acids in the blood flowing to the muscles or to the presence of a liver which, in proportion to the size of the organism, is relatively larger than the normal. SUMMARY OF PREVIOUS INVESTIGATIONS. In spite of the wide variations observed in the increase of the metab- olism with different foodstuffs, there is a distinct uniformity in the majority of experiments which indicates that the act of taking food results in an increased heat production, carbon-dioxide production, and oxygen consumption. With diets predominating in carbohydrates, the quantitative relationship of these increases is more strikingly noticed in the carbon-dioxide production. With the protein diets, the evidence is more pronounced with the oxygen consumption. With the three typical nutrients we may consider as firmly established: (1) that the ingestion of a diet rich in protein results in a marked increase in the total metabolism both for the oxygen consumption and the carbon- dioxide production, this increase being, in general, roughly proportional to the amount of protein ingested ; and (2) that with carbohydrate there is almost invariably a marked increase in the excretion of carbon diox- ide, and in many instances, especially with sugars other than dextrose, there is likewise an increase in the oxygen consumption. The exact interpretation of the increases with carbohydrate is not so simple as in the case of protein, for there is undoubtedly a formation of fat from carbohydrate. In respiration experiments in which only the carbon- dioxide production is determined, the interpretation of the increase is obviously very difficult. With a fat diet, the evidence is conflicting and little information is obtainable. Pure fat is rarely given in experi- ments, but is usually combined with other food materials. In those instances in which it has been included in a mixed diet, a small increase has usually been noted. Two of three experiments made by Gigon with pure olive oil implied a distinct lowering of the basal metabolism. In any event, it is safe to conclude that the influence of the ingestion of fat upon metabolism is very small compared with that of sugar and protein. Although a considerable portion of the literature is devoted to a dis- cussion of the causes of these variations in the metabolism, the two main theories have been (1) the Verdauungsarbeit theory of Zuntz and his scholars, which ascribes the greater proportion of the increased metabolism to the work of digestion, and (2) the specific dynamic BASAL METABOLISM. 47 action theory of Rubner. Clear-cut evidence for or against these theories is, in spite of the great mass of experimental data, not readily found. Writers are about evenly divided between the two theories. Those upholding the Verdauungsarbeit theory have the distinct advan- tage of having a definite process to consider. On the other hand, the definition of the specific dynamic action in Rubner's theory, and more particularly the application of the theory, is somewhat obscure and has led to a great deal of confusion. It should be stated, however, that few theories regarding the physiology of digestion have stimulated so much excellent research work as has the specific dynamic action theory. BASAL METABOLISM. To study the influence upon metabolism of such a factor as the inges- tion of food, the energy requirements of the quiescent body prior to the ingestion of the food must be known, for otherwise the measurement of metabolism after food can have no comparative significance. Thus the whole problem of demonstrating the influence of the ingestion of food upon metabolism depends upon two vitally important processes: (1) the establishment of a suitable base-line, and (2) the accurate meas- urement of metabolism following the ingestion of food. While at first sight it might be assumed that the establishment of a base-line is relatively simple, close analysis shows that this is far from being the case. In the first place, there is no normal value for either male or female adults that may be taken, a priori, as a base-line for any subsequent measurements. Various attempts have been made to establish more or less crude "standard" values and results have been obtained which give rough indications of the major changes in metabo- lism due to disease, food, or muscular work. These so-called standard values can not, however, be used for any quantitative study of the influence of a specific factor upon metabolism. Each series of measure- ments accordingly demands its own basal determination. In determining basal values, the conditions should preferably be as much as possible like those obtaining during the comparison experi- ments. Thus, in any research on the effects of bicycle riding, it may be fairly argued that the base-line should be determined not when the subject is lying in deep sleep, but when he is sitting in the ordinary position occupied by a bicycle rider. Again, when the work of hori- zontal walking is studied, the base-line would not logically be that obtained during deep sleep, but would be a value secured with the subject standing in readiness for walking. The degree of care necessary in the selection of a base-line is depend- ent upon the size of the increment in the metabolism due to the super- imposed factor. By active muscular work it is perfectly possible for a well-trained athlete to increase his basal metabolism tenfold or more, 48 FOOD INGESTION AND ENERGY TRANSFORMATIONS. the professional bicycle rider studied by us1 and also the one studied by Benedict and Cathcart2 showing no difficulty in producing such increases. With values so large as these, it is clear that small differ- ences in the base-line play a comparatively unimportant role. Indeed, it has been the custom in the researches on muscular work, published not only from this laboratory but also by investigators elsewhere, to use a basal value determined with the subject lying down but not asleep. While such a practice is theoretically unsound, the increments due to muscular work are so large that in comparisons of metabolism during muscular work and during rest the relatively slight differences between metabolism during sleep and that with the subject standing or sitting quietly or lying down awake may be neglected. In studies on the influence of food upon metabolism, the increments are much smaller than in studies with muscular work. A glance at the literature (see pages 10 to 46) shows that the maximum effect due to this factor may be to increase metabolism for a short time, possibly 30 or even 40 per cent. When we consider the potential increment of 1 ,000 or more per cent with muscular work, even this maximum increase in metabolism after food seems comparatively insignificant. Accord- ingly, in a study on the effect of the ingestion of food, great care should be taken to secure a uniform base-line and a critical examination should be made of those factors liable to influence the determination of the basal metabolism. The quiescent metabolism of the body may be affected by a number of factors, primarily by muscular activity. We have already seen that severe muscular work increases the metabolism largely, but we find that moderate activity or even the relatively few muscular movements that distinguish between complete rest and ordinary rest also have a definite influence. Furthermore, when the increment in metabolism to be measured is probably small, one has to consider not only minor muscular activity, but even the degree of muscular relaxa- tion. Thus we find Johansson3 training himself and his co-workers to establish an arbitrarily complete muscular repose. Finally, experi- mental evidence4 obtained in the Nutrition Laboratory has shown positively that the quiescent metabolism of a subject asleep differs con- siderably from that of the same subject awake. In experiments with the subject in a profound sleep there was a noticeable decrease in pulse rate, which was almost invariably accompanied by a decrease in total metabolism. We may expect, therefore, that with the subject in deep sleep there will be a decrease in pulse rate, respiration rate, and muscle tonus, with consequently lower metabolism as compared with values 'Benedict and Carpenter, U. S. Dept. Agr., Office Exp. Stas. Bull. 208, 1909. "Benedict and Cathcart, Carnegie Inst. Wash. Pub. No. 187, 1913. 'Johansson, Skand. Arch. f. Physiol., 1S9K, 8, p. 119. 'Benedict, Carnegie Inst. Wash. Pub. No. 203, 1915, p. 343. BASAL METABOLISM. 49 obtained with the same subject awake and in complete muscular repose. Even though the body be muscularly quiet while lying on a couch or bed and the voluntary muscles be perfectly controlled, the involuntary muscles, such as those of circulation, digestion, and respiration, are active. These involuntary muscles continue their work in deep sleep at a somewhat lower level. A second factor which definitely affects the base-line is previously ingested food. It has been clearly demonstrated by practically all of the earlier workers that an increased metabolism follows the taking of food, particularly when protein and certain carbohydrates form a part of the diet. If possible, therefore, we must find a point in the digestive cycle at which the metabolism will not be influenced by the previous diet, but which will be prior to the severe drafts upon the body glycogen that have been found in researches at both Wesleyan University and the Nutrition Laboratory during several days of strict fasting. It seems to be the consensus of opinion of nearly all experimenters in this line of research that with normal man, unless the last meal has been excessively rich in protein, active digestion ceases 12 hours after the ingestion of food and the metabolism has then reached essentially the normal level, i. e., the level prior to the taking of food. This has been demonstrated in a number of researches, particularly those of Magnus- Levy.1 Hence it is now the custom of most experimenters to study the basal metabolism by making experiments 12 or 14 hours after the last meal or, as Benedict and Cathcart have expressed it, with the subject in the "post-absorptive condition/'2 and to assume that the influence of previously ingested food will in this way be eliminated.3 The metabolism at this time, however, does not always represent the mini- mum metabolism, as will be seen in a later discussion. At this point we may ask: What is the lowest metabolism? If in a normal state of nutrition the voluntary muscles of the body are so per- fectly controlled that there is no visible movement, the muscles so relaxed as to diminish the muscle tonus, the pulse rate and the respira- tion rate depressed to the lowest point, and there is no food in the ali- mentary tract, and furthermore, if the subject is in deep sleep, we may expect to obtain the minimum metabolism for that particular subject. The ideal conditions outlined for obtaining such a low metabolism are, as a matter of fact, not readily secured with the majority of subjects. If in studying the influence of a superimposed factor upon metabolism, the measured base-line can be relied upon as uniform, it is not necessary that the lowest metabolism be secured. In experiments which involve relatively slight changes in metabolism, however, the lower the metab- olism which can be secured for the base-line, the greater will be the Magnus-Levy, Arch, f . d. ges. Physiol., 1894, 55, p. 1 ; see especially p. 23. 2Benedict and Cathcart, Carnegie Inst. Wash. Pub. No. 187, 1913, p. 71. 'Benedict and Higgins, Am. Journ. Physiol., 1912, 30, p. 217. 50 FOOD INGESTION AND ENERGY TRANSFORMATIONS. degree of accuracy in the percentage increase obtained as a result of the superimposed factor. Even when the basal value has been well established it does not necessarily follow that the metabolism of an individual will remain unchanged for an indefinite length of time, inasmuch as there will be changes in the composition of the body, particularly gains or losses of glycogen and fat; growth, climate, the season of the year, and such factors as temperature environment and various stimuli to the body may likewise have an effect upon metabolism. This question will be considered more at length in the discussion of the various methods for obtaining the basal metabolism. Of the numerous factors affecting muscle tonus and nerve stimu- lation, great emaciation and the ravages of disease are distinctly of pathological rather than of physiological significance. In a number of pathological cases, when the metabolism is at a subnormal point through muscular atrophy and similar causes, there may be even less muscle tonus and minor muscular movement than with healthy per- sons in profound sleep. But these abnormal conditions need not be considered here. It may be of considerable moment in this connection to note whether or not the increment above the base-line due to the ingestion of a defi- nite amount of food is wholly independent of the absolute value of the base-line. For example, we will assume that the taking of a certain amount of food resulted in an increment of 25 calories during a period of 6 hours when the base-line was determined with the subject in complete muscular repose, in the post-absorptive condition, and lying awake. With the subject asleep, the base-line would unquestionably have been somewhat lower than that obtained with the subject awake. Have we any reason to believe that the increment due to the ingestion of food will be affected by this difference in conditions? Unfortunately our evidence is by no means clear on this point. The particular problem studied in this publication is the absolute increase in the heat production caused by the ingestion of food. Aside from disease, the two principal factors which contribute to the depres- sion of the base-line are sleep and fasting. It is conceivable that with a low base-line, such as would be found in deep sleep or during fasting, a greater increment would be obtained with a definite amount of food than with a higher base-line. On the other hand, it is possible that during sleep, and especially with a condition of under-nutrition resulting from fasting, the cells may be less susceptible to stimuli. In such a case the increment in the metabolism would obviously be less than when the subject is awake and in a normal state of nutrition. Experiments primarily measuring the output of heat resulting from a definite amount of muscular work have shown that if the basal value BASAL METABOLISM. 51 is increased for any reason, either by previous alcoholic excess1 or by preceding diet,2 the increment in the heat production per unit of work is not measurably altered. This is in full conformity with the contention of Johansson and Koraen3 to the effect that the thermal processes accompanying food ingestion and those accompanying muscular work are entirely distinct from each other. The only striking illustrations in the literature of the opposite of this hypothesis are the observations of Durig,4 whose technique it is very difficult to criticize adversely; his results should therefore be considered as absolutely established facts. In Durig's Vienna experiments the basal metabolism was approximately 1 calorie per minute, while in the Monte Rosa experi- ments it was 1.26 calories per minute. The increment due to the ingestion of sugar was 0.268 and 0.306 calorie per minute in Vienna; on Monte Rosa with the same amount of sugar it was 0.206 and 0.115 calorie per minute. It would seem, therefore, as if with the higher base- line the sugar had a less stimulating effect. For all practical purposes, however, we need not at present consider these special conditions, but may assume that if the base-line is deter- mined under conditions of complete muscular repose, the increment measured will represent the true effect of the ingestion of food upon the metabolism irrespective of whether the subject is asleep or awake. The possible variations in the magnitude of this effect, due to the sub- ject being either asleep or awake, call for experimental evidence, and as yet we have none at hand. BASAL VALUES USED IN THIS RESEARCH. As the researches recorded in this publication have extended over a considerable period of time, namely, from 1904 to 1915, and this period has witnessed a rapid development of technique in all forms of metab- olism measurements, it is not surprising that we find variations in the interpretation of the significance and importance of the base-line and in the method of studying the metabolism following food ingestion. The experiments reported in this publication may be divided into three groups: First, those 24 hours in length; second, those approxi- mately 8 hours in length; and third, those in which the individual periods were of short duration. The variations in the length of the period naturally resulted in a variation in the method of obtaining the basal metabolism. In the 24-hour experiments the basal metabolism was determined for each individual for one or more days and compared with 24-hour values determined on other days for the metabolism after food ingestion. In the earlier 8-hour experiments, the basal metab- *Benedict and Murschhauser, Carnegie Inst. Wash. Pub. No. 231, 1915, p. 78. 2/btd., pp. 80 and 93. 'Johansson and Koraen, Skand. Arch. f. Physiol., 1902, 13, p. 251. *Durifi;, Denkschr. d. Wiener Akad. d. Wiss., 1909. 86, p. 116. 52 FOOD INGESTION AND ENERGY TRANSFORMATIONS. olism and the metabolism after food were determined on separate days, but later in the research the food was frequently given after several hours of fasting and the measurements continued for the remainder of the 8 hours. Thus, in these later experiments, the basal metabolism and the metabolism after food were determined on the same day. In the short-period experiments the basal metabolism was measured on the same plan as that used in most of the later 8-hour experiments, i. e., in several periods preceding the ingestion of food. Both the 24-hour experiments and the 8-hour experiments were carried out with respiration calorimeters, by means of which not only the carbon-dioxide production and the oxygen consumption could be measured, but also the heat production. The short-period experi- ments, in which the individual periods were approximately 15 minutes long, were made with respiration apparatus which gave measurements of only the carbon-dioxide production and the oxygen consumption. The heat production was calculated by the indirect method. The main object in all these experiments wras essentially the same, namely, to secure a constant base-line upon which could be superim- posed the factor of the ingestion of food. With the 24-hour base-line it was necessary to assume that the metabolism was constant from day to day; with the earlier 8-hour base-line, that it was constant on differ- ent days; and in the experiments in which the base-line was determined on the same day as the metabolism after food (the later 8-hour experi- ments and the short-period experiments), that the metabolism was constant from hour to hour throughout the day. From a consideration of these plans of experimenting it is easily seen that the probability of constancy in muscular activity is not the same for all types of experiments. The advantages and disadvantages of each method may therefore be discussed more in detail in connection with the results obtained in the determinations of the basal metabolism. EXPERIMENTS OF 24 HOURS' DURATION. The earliest experiments included in this study, which were made with the respiration calorimeter at Wesleyan University, Middletown, Connecticut, used the 24-hour day as a unit. This was in accordance with the usage of the Munich school of Carl Voit, in which Professor W. 0. Atwater of Wesleyan University obtained his introduction to metabolism experiments; practically all of the researches with the large calorimeter at Wesleyan University which have been published since 1897 have been based upon the 24-hour day. A study of the metabolism during inanition was first attempted with the idea of using the results of the fasting experiments as a base-line in a supplementary study of the effect upon metabolism of the inges- lion of food. This was done in the belief that a knowledge of the BASAL METABOLISM. 53 gaseous metabolism and energy transformations during prolonged fasting would be of fundamental importance, and furthermore, that after such a fast ideal conditions would be present for studying the superimposed factor of the ingestion of food. These fasting experiments varied in length from 1 to 7 days. To obtain like activity in the basal periods and in those following food, it was the custom to watch the subject continuously during the fasting period and to record each movement. A program was then prepared, duplicating in every detail the movements of the fasting period, and in the comparison food experiment the subject was requested to follow this program faithfully. It was assumed that the narrow confines of the chamber and the routine program would so restrict the muscular activity of the subject on the food days that the degree of intensity would approximate that of the fast days. The experiments as planned included one or more periods of observa- tion when the subject was lying, presumably asleep, inside of the respi- ration chamber; it was believed that these periods would give ample opportunity for studying the most quiet metabolism of the fasting individual. At that time evidence was not secured regarding the con- stancy in the degree of muscular repose during these sleeping periods, aside from the reports of the subjects themselves as to their condition during the night. It was almost invariably reported that the subject slept moderately well. Certainly the men did not at any time leave the couch and the muscular activity, if there were such, did not cause a sufficient heat disturbance to attract the attention of the physical observer. The influence of the ingestion of food was determined by noting the basal metabolism in 24 hours without food and comparing it with the metabolism during a 24-hour period in which a particular diet was ingested, the increment in the metabolism showing the increase due to the ingestion of the food. CRITIQUE OF 24-HOUR METHOD. This method of determining the metabolism in 24-hour periods has been regularly employed by many investigators. It was used by Johansson and his associates1 in the Stockholm laboratory in consider- ing the effects of food following a 5-day fast. In Johansson's experi- ments the food ingestion immediately followed or immediately preceded the fasting days. In the experiment of 5 consecutive days reported by Rubner,2 on the first day there was hunger and rest, on the second protein diet and rest, on the third protein diet and work, on the fourth sugar diet and rest, and on the fifth sugar diet and work. 'Johansson, Landergren, Sonden, and Tigerstedt, Skand. Arch. f. Physiol., 1897. 7, p. 20. "Rubner, Sitzber. K. Preuss. Akad. Wiss., 1910, p. 316. 54 FOOD INGESTION AND ENERGY TRANSFORMATIONS. Theoretically the measurement of the basal value during a 24-hour fast, to be immediately followed by a day in which the prescribed food intake is given, is an ideal method for studying the influence of the ingestion of food, inasmuch as it includes the activities of a complete normal day. The subject is thus awake during the major part of the 24-hour period and asleep the normal time, the movements being restricted to those possible inside a respiration chamber, such as dress- ing and undressing, drinking water, telephoning, urinating, and similar activities. By means of the program prepared for the subject, this daily cycle of normal activity could be approximately duplicated in comparison experiments without difficulty. In some respects the longer periods are pleasanter for the subject, as more freedom is allow- able in the routine and strict muscular repose is not necessary. As the total amounts of carbon dioxide given off and oxygen con- sumed are relatively large in a 24-hour experiment, the experimental errors are practically eliminated; the chemical and physical measure- ments thus have a greater degree of manipulative accuracy than is the case in short periods. Furthermore, the continuance of food experiments for 24 hours insures a complete measurement of the effect of food, especially with certain diets, for undoubtedly the influence lasts at times longer than the 12 hours usually assumed to establish post-absorptive conditions. Finally, the long-period experiment allows the ingestion of food at the regular times of the day and in the regular amounts, thus permitting a summation effect and the obtaining of information as to the influence of the diet upon the basal metabolism for the whole day. On the other hand, the 24-hour period can not give a minimum metabolism value for the subject, since it necessarily includes so much extraneous muscular activity. Although the method used to secure comparable activity in the experiments was as satisfactory as was then possible, it could give only an approximate control, with no assurance of perfect uniformity. Ocular evidence of the activity is at best more or less unreliable, as observers vary widely in their estimates of the quantitative relationships of various minor muscular movements. The 24-hour type of experiment has yet another disadvantage, for although the deprivation of food for 24 hours is by no means so great a hardship as would ordinarily be supposed, yet the enforced abstinence from food for this length of time is not borne so cheerfully by the ma- jority of individuals as is the short-period fasting. Again, the 24-hour period gives no information as to the time rela- tions or the maximum effect following the ingestion of food. We are thus unable to tell from the results whether the increase extends over a long period or whether there is a sharp rise and fall in metabolism, i. e., a "peak" effect. Nor does it take into consideration the remote possibility of a compensation — that is, a subsequent lowering of metab- BASAL METABOLISM. 55 olism. The evidence as a rule indicates an increment in metabolism, but certain experiments, as we have seen in the summary of the liter- ature on this subject (see page 40), have at least suggested a depression of the basal metabolism. Furthermore, with the 24-hour period it is practically impossible to detect slight increases, which may actually occur but be lost in the daily quota. These increases could be demonstrated if the maximum effect could be obtained by means of measurements in short periods immediately following the ingestion of food. In a study on the influ- ence of food upon metabolism it would therefore be expected that the 24-hour type of experiment could be satisfactorily used only when studying classes of foods which produce a considerable increment in metabolism rather than for securing evidence regarding foods which cause but a slight increase in metabolism. DISCUSSION OF RESULTS OF FASTING AND FOOD EXPERIMENTS ON THE 24-HOUR BASIS. In view of the results obtained in the fasting studies carried out at Wesleyan University and later in the Nutrition Laboratory, the selec- tion of a suitable basal value to be used for the 24-hour food experi- ments has been a subject of much consideration. As will be shown later, in our discussion of the experiments and in our conclusions as to the use of this type of experiment, the length of the fast influences the increment in the metabolism due to the ingestion of food. In discussing the basal metabolism in this special group of 24-hour experi- ments, therefore, it has seemed desirable to give the detailed results obtained after the taking of food, presenting only those fasting values which have been selected for the base-line. The data for the food ex- periments, when significant, will later be included in abstract in several tabular presentations of final results and in the discussion of special food topics. They are presented here primarily as material for a critical study of the general principle of the use of 24-hour periods. In giving the data for these experiments, the fuel value of the diet, i. e., the heat of combustion less the unoxidized portion of the protein excreted in the urine, has been used in all cases. For the method employed in calculating these values, see page 334. The first series of experiments on the 24-hour basis is that for A. L. L., December 16 to 23, 1904.1 In this series 4 fasting days preceded the ingestion of milk and plasmon. In table 7 the average of the first 2 days is used as a base-line, these values being the best available for comparison, as will be shown later (see page 70). The average excre- tion of nitrogen for the first 2 days of fast was 12.18 grams, the carbon- dioxide production 649 grams, the oxygen consumption 615 grams, and 'For the detailed results of this aeries gee Benedict, Carnegie Inst. Wash. Pub. No. 77, 1907, experiments Nos. 69 and 70. 56 FOOD INGESTION AND ENERGY TRANSFORMATIONS. the heat production 2,057 calories. An examination of the values for the fourth day of fast, December 19 to 20, shows that they are somewhat lower than the basal values obtained from an average of the first 2 days. On all of the 3 food days there was a gradual increase in the carbon-dioxide excretion, oxygen consumption, and heat production as a result of the ingestion of the milk and plasmon, the largest amount being on the last day. Thus, on the 3 days with food there were suc- cessive increases of 4, 37, and 128 grams in the carbon-dioxide pro- duction, 7, 56, and 118 grams in the oxygen consumption, and 47, 166, and 400 calories in the heat production. TABLE 7. — A. L. L., December 16-23, 1904. (24-hour periods, 7 a. m. to 7 a. m.) Milk and plasmon:1 Amount, 1,021 grams; nitrogen, 8.57 grams; total energy, 2,577 calories. Fuel value, 2,502 calories; from protein, 9 per cent; from fat, 79 per cent; from carbohydrates, 12 per cent. Experi- mental Date. Nitrogen Carbon dioxide. Oxygen. Heat. in urine. day. Total. Increase. Total. Increase. Total. Increase. Fast: 1904. grams. gra?ns. grams. grains. grams. cats. cals. First... Dec. 16-17.. 10.09 632 584 1,951 Second . Dec. 17-18.. 14.26 666 646 2,163 Third.. Dec. 18-19.. 15.04 641 619 2,035 Fourth . Dec. 19-20. . 12.97 613 601 1,958 Av. first 2 days 12 18 649 615 2,057 Food: First . . . Dec. 20-21.. 13.04 653 4 622 7 2,104 47 Second . Dec. 21-22.. 9.84 686 37 671 56 2,223 166 Third . . Dec. 22-23. . 10.15 777 128 733 118 2,457 400 'Expressed as average per day, since the amounts and nutrients were essentially the same each day. With this particular experiment, in which an increment was noted on all 3 days with food, the discussion of the results is comparatively simple. Judging by this experiment alone, it is clear that the ingestion of food increased the metabolism over that of the fourth day of fasting, thus bringing the values for the first food day positively above the average for the first 2 days of fasting; there was also a cumu- lative effect, for although exactly the same amount of food was given each day and there was apparently the same amount of muscular activity, the metabolism distinctly increased each day. This increase amounted on the first day to but 2 per cent of the fuel value of the intake, on the second day to 7 per cent, and on the third day to 16 per cent. As only a small amount of plasmon was taken and the milk used was a modified milk and contained considerable fat, the actual BASAL METABOLISM. 57 amount of nitrogen ingested was not large; hence the increment due to the stimulating action of protein could not be expected to be very great. In addition, it should be pointed out that 79 per cent of the energy came from milk fat. Obviously if the last day of fasting were taken as the base-line, all of the increments would be materially larger. The next series of experiments, that with S. A. B., January 7 to 12, 1905, included a 4-day fasting experiment, followed by a food experi- ment of only one day, as the subject was unable to continue the diet longer.1 The results of this latter experiment are given in table 8. The food consisted of the somewhat unusual combination of a modified milk and orange juice, a diet insisted upon by the subject as a SUP- TABLE 8. — S. A. B., January 8-12, 1905. (24-hour periods, 7 a. m. to 7 a. m.) Milk and orange juice: Amount, 1,359 grams; nitrogen, 6.24 grams; total energy, 1,752 calories. Fuel value, 1,698 calories; from protein, 9 per cent; from fat, 73 per cent; from carbohydrates, 18 per cent. Experimental day. Date. Nitrogen in urine. Carbon dioxide. Oxygen. Heat. Fast: Second1 .... Third . 1905. Jan. 8-9.. Jan. 9-10. grams. 11.04 13.10 grams. 570 554 grains. 554 538 cals. 1,844 1,746 Fourth Jan. 10-11. . 10.74 508 493 1,606 Food : First .... Second day. Jan. 11-12.. 11.04 10.66 570 525 554 517 1,844 1,677 1First day not included because of work done on bicycle ergometer. posedly advantageous method of breaking a moderately long fast. As on the first day of fasting there was more muscular activity than usual, the values obtained on that day are not suitable for a base-line. The food values are therefore compared with those for the second day of the fast. On comparing the fasting and food values, we find that this experiment differs from that preceding in that here the digestive activity produced no increment in the metabolism, the values for the food day being lower than those for the second day of fast. On the other hand, when the fourth day is used as a base-line, there appears to be an increase in the metabolism after the food. It should be noted in this connection that the amount of energy in the diet from both protein and carbohydrates was small, the total fuel value of the food being only 1,698 calories. The only deduction which can be made from this experiment is that after 4 days of fast, the ingestion of 1,359 grams of food of the composition noted was not sufficient to raise the 'For the detailed results of this series, see Benedict, Carnegie Inst. Wash. Pub. No. 77, 1907, experiments Nos. 71 and 72. 58 FOOD INGESTION AND ENERGY TRANSFORMATIONS. metabolism above the level of the second day of fast, although the values were somewhat increased by the food over those obtained for all the factors during the fourth fasting day, which immediately pre- ceded the taking of the milk and orange juice. Somewhat similar conditions exist in the next series of experiments with the same subject S. A. B., January 28 to February 5, 1905. l This consisted of a 5-day fasting experiment, followed by a 3-day food experiment. (See table 9.) A mixed diet was used, consisting of modi- fied milk, orange juice, a small quantity of apple, and a few graham crackers. This diet was somewhat above maintenance in energy, but small in nitrogen content. After 5 days of continuous fasting, the effect of the amount of food taken was not sufficient to bring the metab- TABLE 9. — S. A. B., January SB-February 5, 1905. (24-hour periods, 7 a. m. to 7 a. m.) Mixed diet (per day) : Amount, 1,671 grams; nitrogen, 6.37 grama; total energy, 2,133 calories. Fuel value, 2,078 calories; from protein, 8 per cent; from fat, 65 per cent; from carbohydrates, 27 per cent. Experimental day. Date. Nitrogen in urine. Carbon dioxide. Oxygen. Heat. Fast : First 1905. Jan. 28-29 grams. 10.29 grams. 609 grams. 544 cals. 1,866 Second . . . Jan. 29-30 11 97 560 548 1,791 Third Jan. 30-31 11 54 542 533 1,739 Fourth Jan. 31-Feb. 1 10 39 515 503 1,663 Fifth Feb. 1-2 9.98 482 486 1,548 Food: First Av. first two days. Feb. 2-3 11.13 10 74 585 529 546 612 1,829 1 691 Second Feb. 3-4 8.25 53D 489 1,585 Third Feb. 4-5 6.78 527 495 1,607 olism up to the values obtained on the first 2 days of the fast. Nor did the continued ingestion of the food materially alter the total metabolism in any way. The results of this experiment are in striking contrast to those obtained for A. L. L., on December 16 to 23, 1904 (see table 7, page 56), in which there was a continued increase in the values obtained on the food days. The fuel value of the food used for the experiment with A. L. L. was, however, about 25 per cent higher than that given to S. A. B. If the results for the fifth day of the fast are used as a base-line in this experiment with S. A. B., the metabolism on the food days will show a positive increment for all 3 days, although the increment on the second day is very small for both the oxygen consumption and the heat production. Indeed, the food experiment in this series seems to indicate simply a maintenance of the fasting 'For the detailed results of this experiment, see Benedict, Carnegie Inst. Wash. Pub. No. 77, 1907, experiments Nos. 73 and 74. BASAL METABOLISM. 59 value originally established at the end of the fifth day of fasting, for it is apparent that although the body requirement was only about 1,600 calories, the ingestion of food having a fuel value of about 2,000 calories was not sufficient to raise the metabolism to the initial level of the first two fasting days, i. e., 1,800 calories. In this, as in all other experiments, strict attention was paid to the necessity of securing comparable conditions of muscular activity. Such variations as were unquestionably present have been carefully discussed in detail in a previous publication.1 The data there given show that the energy of the estimated muscular activity was extraordinarily constant through- out the 5 days of fasting and the 3 days with food; the difference can not therefore be explained by differences in muscular activity. Still another series of experiments was made with this subject March 4 to 14, 1905, in which the fasting experiment continued for 7 days and the food experiment 3 days.2 The diet in the food experi- ment consisted of milk, gluten crackers, an apple, orange juice, and a small quantity of a breakfast food. As shown in table 10, the average value for the heat production for the first 2 days was 1,767 calories. TABLE 10.— S. A. B., March 4-14, 1905. (24-hour periods, 7 a. m. to 7 a. m.) Mixed diet (per day): Amount, 1,274 grams; nitrogen, 6.45 grams; total energy, 1,841 calories. Fuel value, 1,788 calories; from protein, 9 per cent; from fat, 37 per cent; from carbohydrates, 54 per cent. Experimental day. Date. Nitrogen in urine. Carbon dioxide. Oxygen. Heat. Fast: First 1905. Mar. 4— 5 ... grains. 12.24 grams. 570 grams. 534 cats. 1,765 Second Mar. 5- 6 12.45 551 534 1,768 Third . ... Mar. 6- 7 13.02 545 536 1,797 Fourth .... Mar. 7- 8 11.63 534 520 1,775 Fifth Mar. 8- 9 10.87 496 491 1,649 Sixth Mar. 9-10 10.74 477 466 1,553 Seventh .... Mar. 10-11 10.13 476 466 1,568 Food: First Av. first two days . Mar. 11-12 12.35 10.17 561 551 534 527 1,767 1,767 Second ... . Mar. 12-13 7.15 560 500 1,728 Third Mar. 13-14 7.82 608 507 1,754 After the ingestion of the mixed diet, which had a fuel value of 1,788 calories, the metabolism returned to the level of the first 2 days, but was not raised above it. It was, however, about 200 calories higher than the metabolism on the seventh day of the fast. Thereafter the metabolism remained essentially constant, the progressive increment Benedict, Carnegie Inst. Wash. Pub. No. 77, 1907, p. 486, table 234. 2For the detailed results of this experiment, see Benedict, Carnegie Inst. Wash. Pub. No. 77, 1907, experiments Nos. 75 and 76. 60 FOOD INGESTION AND ENERGY TRANSFORMATIONS. noted with A. L. L. being absent. We have here, therefore, the singu- lar fact that this diet was sufficient to raise the metabolism after 7 days of fast to the initial level of the first 2 days of the fast, while in the experiment with the same subject on February 2 to 5, a diet containing about 300 more calories was not able to produce this effect. An analysis of the character of the diet shows that the percentage of protein was essentially the same in both instances, but that the carbo- hydrate contained double the amount of energy in this experiment, with a corresponding reduction in the proportion from fat. It is not impossible, therefore, that the action of the carbohydrate accounts for the apparent discrepancy between the two sets of results. Since even in this experiment there was no evidence of an increment if the first 2 days of fasting are taken as a base-line, we can consider the stimu- lating effect of the food as simply compensating for the decrease in the metabolism produced by the specific effect of the fasting. It is only when this depressing influence of fasting has been completely overcome that the stimulating action of the food is apparent. In the plan of experimentation thus far used it is clear that the problem is dis- tinctly complicated by the conditions involving the depressant effect of a prolonged fast and by the attempt to superimpose the stimulating effect of the ingested food. As a result of the somewhat unsatisfactory experience with fairly long preliminary fasts, the experimental plan was altered so as to include fasts of only 2 days' duration in an attempt to minimize the depressing influence of the fasting and yet to secure a suitable base- line for determining the influence of food. Several experiments were made on this plan. The fasting data have already been published for most of these experiments,1 but the results are repeated in abstract here. The first series of experiments on this later plan was made with H. R. D., December 5 to 8, 1905, there being 2 days of fasting followed by 1 day with a mixed diet. The metabolism on the 2 days of fasting was remarkably constant, with an average heat production of 1,910 calories. On the food day the heat production increased practically 190 calories after the ingestion of food having a fuel value of 2,086 calories. In this instance, therefore, the fasting did not so depress the metabolism as to make it unresponsive to the stimulus of the ingested food. It should be noted that the percentage of energy from protein was somewhat larger than in the experiments thus far considered and the proportion from carbohydrates was likewise large. The details are given in table 11. A series of experiments was also made with N. M. P., December 9 to 12, 1905, in which a mixed diet was given. (See table 12.) The fasting experiments do not show so close an agreement as was found 'Benedict, Carnegie Inst. Wash. Pub. No. 77, 1907, p. 222. BASAL METABOLISM. 61 in the preceding series with H. R. D., the individual values being 2,109 and 2,305 calories for the heat production, with an average of 2,207 calories. The food was taken at the usual meal times and the quanti- ties were so adjusted that a large amount could be eaten by the subject. The metabolism was considerably increased by the food, the incre- ment in the carbon-dioxide production being 180 grams, in the oxygen TABLE 11.— //. R. D., December 5-S, 1905. (24-hour periods, 7 a. m. to 7 a. m.) Mixed diet:1 Amount, 2,010 grams; nitrogen, 12.66 grams; total energy, 2,197 calories. Fuel value: Total, 2,086 calories; from protein, 16 per cent ; from fat, 35 per cent ; from carbohydrates, 49 per cent. Date. Nitrogen in urine. Carboii dioxide. Oxygen. Heat, Total. Increase. Total. Increase. Total. Increase. 1905. Without food : Dec. 5-6. . . . Dec. 6-7 Average. . grams. 13.25 13 . 53 grams. 607 579 grains. grams. 585 554 grams. cals. 1,914 1,907 cals. 13.39 593 570 1.910 With food : Dec. 7-8.... 11.97 666 73 626 56 2,099 189 'The food was eaten mostly in three portions, at 9 a. m., 2 p. m., and 6 p. m. TABLE 12. — N. M. P., December 9-12, 1905. (24-hour periods, 7 a. m. to 7 a. m.) Mixed diet:1 Amount, 3,098 grams; nitrogen, 23.54 grams; total energy, 4,690 calories. Fuel value: Total, 4,486 calories; from protein, 14 per cent; from fat, 30 per cent; from carbohydrates, 56 per cent. Date. Nitrogen in urine. Carbon dioxide. Oxygen. Heat. Total. Increase. Total. Increase. Total. Increase. 1905. Without food : Dec. 9-10.. Dec. 10-11.. Average. . grams. 11.37 11.35 grams. 697 719 grams. grams. 628 676 grams. cals. 2,109 2,305 cals. 11.36 70S 652 2,207 With food: Dec. 11-12.. 17.64 888 180 756 104 2,586 379 xThe food was eaten in four portions, at 8 a. m., 1 p. m., 6 p. m., and lONJO01 p. m consumption 104 grams, and in the heat production 379 calories. That this increase was coincidental with the ingestion of a large amount of nitrogen and with a considerable part of the fuel value coming from carbohydrate is not surprising. The fuel value of the total diet was practically twice the daily requirements in the fasting period. The noticeable increase in the nitrogen excretion on the day with food is explained by the high nitrogen content of the diet. 62 FOOD INGESTION AND ENERGY TRANSFORMATIONS. A series of experiments was carried out with D. W., January 10 to 14, 1906, which was similar in plan to those with H. R. D. and N. M. P., except that the food experiment was continued for a second day. The data are shown in table 13. The two fasting days gave results which agree fairly well with each other. After the ingestion of a TABLE 13. — D. W., January 10-14, 1906, (24-hour periods, 7 a. m. to 7 a. m.) Mixed diet (per day) .-1 Amount, 616 grams; nitrogen, 5.11 grams; total energy, 988 calories. Fuel value: Total, 943 calories; from protein, 14 percent; from fat, 20 per cent; from carbohydrates, 66 per cent. Date. Nitrogen Carbon dioxide. Oxygen. Heat. in urine. Total. Increase. Total. Increase. Total. Increase. 1906. Without food: grams. grams. grams. grams. grams. cals. cals. Jan. 10-11 . . 9.99 722 645 2,150 Jan. 11-12. . 14.46 706 681 2,254 Average. . 12.23 714 663 .. 2,202 With food ; Jan. 12-13 . . 15.66 721 7 672 9 2,233 31 Jan. 13-14 . . 12.03 775 61 723 60 2,386 184 Breakfast cereal and milk; eaten in three portions each day. mixed diet with a fuel value of only 943 calories, the metabolism on the first day after fasting was very slightly increased — hardly more, indeed, than would be expected as the limit of error. On the second day, with the same diet, the metabolism showed a very perceptible increase of 184 calories, a distinct indication of the influence of the ingestion of food. The results of this experiment are not unlike those found in the food experiments with A. L. L. — the first 24-hour experiment dis- cussed—in which there was a continually increasing metabolism on the days following fasting. In the former case, however, the fuel value was sufficiently large to supply the daily requirements, while in this experiment the fuel value of the food was less than half that of the body needs. Inasmuch as this man was subsisting on an insufficient diet, the experiment with D. W. can hardly be termed an experiment with food, but is more properly classified as an experiment with partial inanition. In this experiment, as in the others, every attempt was made to secure uniformity in the activity. An examination of the records of the physical observer for the second day and of the figures for the total heat production show that the excess heat on this day was given off during the night between 11 p. m. January 12 and 7 a. m. January 13. This heat output can not, therefore, be considered as a digestive function, for the subject reported a very wakeful night; the records also show that he telephoned twice, although on the first day he had not done this. It is thus probable that the increment on this BASAL METABOLISM. 63 second day may in large part be accounted for by the difference in the muscular activity of the two days, especially during the wakeful night, and hence the results are not comparable. All of the food experiments thus far considered were made with a mixed diet. As it seemed desirable to study specific food substances, an experiment was made with one subject, A. H. M., in which an ex- clusively fat diet was given. The basal values for comparison were drawn from a 2-day fasting experiment with the same subject, carried out December 3 to 5, 1906, which was a duplicate of an experiment made on November 21 to 23, 1905. This repetition was due to the fact that, in a complete survey of the figures obtained with the subjects of the short fasts at Wesleyan University, it was found that A. H. M. gave indications of having stored glycogen during the November experi- ment, and it was thus desirable to find if this subject consistently gave abnormal values for katabolized glycogen. The results of the first fasting experiment have been given in full in an earlier publication,1 but the second experiment was made over a year afterward and too late to include in that report. As the results for the fasting experiment December 3 to 5, 1906, have not heretofore been published, the data are given in considerable detail in this publication.2 The routine of this later experiment was but little modified from that of the experiment of November 21 to 23, the records of the body activity being substantially the same as in the earlier experiment. The body-weight without clothing at 7 o'clock each morning was 65.8 kilograms, 64.6 kilograms, and 63.4 kilograms for the 3 days, respec- tively, indicating the usual somewhat rapid loss in weight during the first few days of fasting. The records of the pulse rate, respiration rate, strength tests, and body-temperature did not vary appreciably from the values obtained in the earlier experiments with this subject and with others. On the first fasting day the subject drank 114.7 grams of water and the weight of urine was 526.8 grams; on the second day he drank 186.3 grams of water and the weight of urine was 569.1 grams. The carbon-dioxide production, oxygen consumption, and water vaporization were determined as usual in 2-hour periods through- out the entire experiment; the nitrogen in the urine was also deter- mined. From these values the complete metabolism was obtained. The data for the total carbon-dioxide production, oxygen consumption, and heat production, are given in table 14 (see p. 64) ; those obtained from the analysis of the urine are given in table 15. The subdivision of the income and outgo in terms of elements is shown in table 16, while the elements and materials katabolized, which have been com- puted in accordance with the usual method,3 are recorded in table 17. Benedict, Carnegie Inst. Wash. Pub. No. 77, 1907, p. 222 et seq. 2See, also, statistics for the fasting days Dec. 3 to 5, 1906, on p. 251. 3Benedict, Carnegie Inst. Wash. Pub. No. 77, 1907, p. 37. 64 FOOD INGESTION AND ENERGY TRANSFORMATIONS. A comparison of the energy as computed from body material katab- olized with the heat production as measured is given in table 18. TABLE 14.— A. H. M., December 3-6, 1906. (24-hour periods, 7 a. m. to 7 a. m.) Mayonnaise, lettuce, and lemon: Amount, 213 grams; nitrogen, 0.37 gram; energy, 1,112 calories. Fuel value: Total, 1,109 calories; from protein, 1 per cent; from fat, 98 percent; from carbohydrates, 1 per cent. Carbon dioxide. Oxygen. Heat. Date. Nitrogen in urine. Total. Increase. Total. Increase. Total. Increase. 1906. Without food: grams. grams. grams. grams. grams. cals. cals. Dec. 3-4 9.15 605 545 1,830 Dec. 4-5 13.07 595 565 1,947 Average. . 11.11 600 555 1,889 With food:1 Dec. 6-6 13.05 596 -4 565 10 1,918 29 'Subject finished eating about 2f hours after beginning of period. TABLE 15. — Weight, composition, and heat of combustion of urine in fasting experiment with A. H. M., December 3-5, 1906. Preliminary, Dec. 2-3, 1906. Dec. 3-4, 1906. Dec. 4-5, 1906. (a) Total weight grams . . 1 , 302 . 2 526.8 569.1 (6) Water grams . 625 . 58 (c) Solids, a — 6 . grams 43.52 (d) Nitrogen grams . . 17.51 9.15 13.07 (e) Creatinine (preformed) grams . . 1.191 1.366 (/) Total creatinine grams . . 1.334 1.386 (g) Creatine1 (preformed), f — e. grams . .143 .020 (/i) Chlorine . . . grams 9.392 2.477 1.555 (t) Sodium chloride grams . . 15.498 4.088 2.565 (j) Heat of combustion calories . 76 101 (fc) Specific gravity 1.0271 1.0247 1.0287 JIn terms of creatinine. The carbon-dioxide production and oxygen consumption for the two fasting days agree very closely, but there is a difference of approxi- mately 120 calories in the heat production. The respiratory quotient for the first day of fast was 0.81 and for the second 0.77. These values are somewhat higher than the average values found for all the subjects of short fasts recorded in the earlier report,1 which were for the first day of fast 0.79 and for the second 0.75, although in at least two instances in these short fasts a value was found as high as 0.77 on the second day. Benedict, Carnegie Inst. Wash. Pub. No. 77, 1907, p. 451, table 225. BASAL METABOLISM. 65 TABLE 16. — Elements katabolized in body in fasting experiment with A. H. M., December 3-5, 1906. (a) Total weight. (b) Nitro- gen. (c) Car- bon. (d) Hydro- gen. <«) Oxy- gen. First day, Dec. 8-4, 1906: Income: Oxygen from air grams. 544.8 grams. grams. grams. grams. 544 8 Outgo : Water in urine J496 3 55 5 440 8 Organic matter in urine *26 56 9 15 37 59 42 10 »7 72 Water of respiration and perspiration. . 681.4 76.2 605 2 Carbon dioxide 604.6 164 9 439 7 Total 1,808 86 9 15 172 49 133 80 1 493 42 Loss 1,264 06 9 15 172 49 133 80 948 62 Second day, Dec. 4-5, 1906: Income: Oxygen from air 564.5 564 5 Outgo: Water in urine 525 6 58 8 466 8 Organic matter in urine 237 95 13 07 310 84 43 01 611 03 Water of respiration and perspiration . . 804.3 90.0 714.3 Carbon dioxide 594 9 162 2 432 7 Total 1,962 75 13 07 173 04 151 81 1 624 83 Loss 1,398 25 13 07 173 04 151 81 1 060 33 'Weight of urine less solid matter. Solid matter for Dec. 3-4 calculated from nitrogen by using ratio solld matter for Dec. 4-5, 1906. (See table 15.) N *Sum of nitrogen, carbon, hydrogen, and oxygen. 'NX0.829 (see average ratio — , Benedict, Carnegie Inst. Wash. Pub. No. 77. 1907, table 202, p. 384). N 4NX0.230 (computed ratio — for experiment No. 81; see Benedict, Carnegie Inst. Wash. N Pub. No. 77, 1907, table 168, pp. 258 and 259). 6NX0.844 (computed ratio — for experiment No. 81; see Benedict, Carnegie Inst. Wash. N Pub. No. 77, 1907, table 168, pp. 258 and 259). TABLE 17. — Elements and materials katabolized in body' in fasting experiment with A. H. M. December 3-5, 1906. l Date. Nitro- gen. Car- bon. Hydro- gen. Oxygen. Water. Protein. Fat. Carbo- hydrates (as glycogen) . 1906. Dec. 3-4 grams. 9.2 grams. 172 5 grams. 133 8 grams. 948 6 grams. 970 1 grams. 54 9 grams. 116 9 grams. 123 1 Dec. 4-5 13 1 173 0 151 8 1 060 3 1 128 1 78 4 145 3 47 6 Total, 2 days. 22.3 345.5 285.6 2,008.9 2,098.2 133.3 262.2 170.7 table 16 for methods of obtaining data. 66 FOOD INGESTION AND ENERGY TRANSFORMATIONS. TABLE 18. — Comparison of energy computed from body material katabolized, with heat pro- duction as measured in fatting experiment with A. H. M., December 3-5, 1906. Date. Energy computed from katabolized material. (0) Total heat produc- tion as meas- ured. Heat produc- tion (computed) greater (+) or less (— ) than heat production measured. From body-protein. (d) From body- fat, (e) From body- glycogen. (/) Total (c+d+e) (a) Energy of protein katabo- lized. (6) Poten- tial energy of urine. (c) Net energy (0-6). (A) Amount (f-0). (0 Propor- tion. (h+g). 1906. Dec. 3-4 .... cals. 310 443 cals. 76 101 cals. 234 342 cals. 1,115 1,386 cals. 516 199 cals. 1,865 1,927 cals. 1,830 1,947 calx. +35 -20 p. ct. + 1.9 -1.0 Dec. 4-5 Total, 2 days . Av. per day . . 753 377 177 89 576 288 2,501 1,251 715 358 3,792 1,896 3.777 1,889 + 15 + 8 +0.4 A reference to tables 15 and 16 shows that there was the usual rise in the nitrogen excretion on the second day of fasting. Of particular interest is the fact that the amount of glycogen katabolized, as shown in table 17, was 123.1 grams on the first day and 47.6 grams on the second day, this agreeing very well with the averages found for the other fasting subjects, namely, 110 grams on the first day and 40.3 grams on the second day.1 It is thus clear that the tendency to store glycogen shown in the experi- ment of November 21 to 23, 1905, was not at all characteristic of this subject.2 This fact is further emphasized by the data obtained in the 1-day food experiment with an exclusively fat diet which followed the 2 days of fast, these results showing a further katabolism of glycogen amounting to 47.3 grams. Apparently the subject had by no means exhausted his glycogen supply at the end of the 2 days of fasting, even with a total output of 170.7 grams for the 2 fasting days. Although it is contended that substances other than creatinine affect the Jaffe color reaction and accordingly the determinations of creatine in fasting urine can not be absolutely relied upon,3 it should be noted that in this experiment, as in the earlier fasting experiments, there was evidence of preformed creatine in the urine. As a matter of fact, the 0.02 gram of creatine excreted on the second day of fast (see table 15) is much less than was observed in any of the other fasting experiments, the tendency in the earlier experiments being for this factor to increase somewhat on the second dav rather than to decrease 'Benedict, Carnegie Inst. Wash. Pub. No. 77, 1907, p. 464, table 228. 2/6?'d., p. 222 et seq. •Graham and Poulton, Proc. Royal Soc., ser. B, 1914, 87, p. 205. BASAL METABOLISM. 67 as in this experiment.1 Inasmuch as so long a time has elapsed since the fasting experiment in December 1906 was made, and particularly as full reports of both short and long fasts have been given in recent publications,2 it seems unnecessary to discuss in further detail the results of this experiment. Following the 2-day fasting experiment with A. H. M., December 3 to 5, 1906, a 1-day food experiment was carried out December 5 to 6, in which the somewhat unfortunate attempt was made to have the sub- ject take a considerable amount of olive oil in the form of mayonnaise dressing with lettuce and lemon juice. The results of this experiment are given in table 14. The total amount of food was relatively small, being only 213 grams ; the amount of nitrogen in the food was negligible ; the total fuel value was 1,109 calories, almost entirely from fat, and a little over one-half the amount necessary for maintenance. Under these conditions there was practically no change in the metabolism, for the slight plus and minus values observed in the several columns can not be considered as any larger than would be normally expected in daily fluctuations. TABLE 19. — A. H. M., December 5, 1906. (12-hour periods, 9 a. m. to 9 p. m.) Mayonnaise, lettuce, and lemon: Amount, 213 grams; nitrogen, 0.37 gram; energy, 1,112 calories. Fuel value: Total, 1,109 calories; from protein, 1 per cent; from fat, 98 per cent; from carbohydrates, 1 per cent. Date. Carbon dioxide. Oxygen. Heat. Total. Increase. Total. Increase. Total. Increase. 1906. Without food : Dec. 3 grams. 311 309 grams. grams. 275 285 grams. cols. 965 948 cah. Dec. 4 , Average 310 323 13 280 308 28 957 1,037 80 With food:1 Dec. 5 ... 'Subject finished eating 48 minutes after the beginning of the period. Since the influence of the food, if any, was slight, there is a possi- bility that the effect would be shown during the first few hours after the taking of the food, and would thereafter disappear or even be compensated for in a slight degree. It seemed best, therefore, to analyze this particular experiment further. Consequently the values were computed with a subdivision of the day into 12-hour periods. The results for the period from 9 a. m. to 9 p. m. are given in table 19. On this basis we find a slight increase for all three of the values given, amounting to 13 grams for the carbon-dioxide production, 28 grams for Benedict, Carnegie Inst. Wash. Pub. No. 77, 1907, p. 388, table 203. 2Benedict, Carnegie Inst. Wash. Pub. No. 77, 1907, and No. 203, 1915. 68 FOOD INGESTION AND ENERGY TRANSFORMATIONS. the oxygen consumption, and 80 calories for the heat production. Since all of the factors were distinctly higher than those found on either of the two fasting days, it is reasonable to suppose that the in- creases found represent a positive increment. It is possible that some of this increase may have been due to more activity on the food day in connection with receiving the food, eating it, returning the dishes, increased water drinking, and to defecation.1 TABLE 20.— A. H. M., December 6, 1906. Sitting. (2-hour periods.) Mayonnaise, lettuce, and lemon: Amount, 213 grams; nitrogen, 0.37 gram; energy, 1,112 calories. Fuel value: Total, 1,109 calories; from protein, 1 per cent; from fat, 98 per cent; from carbohydrates, 1 per cent. Basal value (Dec. 3 and 4, 1906), CO2, 52 gms.; O2, 47 gms.; heat, 164 cals. Time Carbon dioxide. Oxygen. Heat. elapsed since subject fin- ished eating. Total. Increase. Total. Increase. Total. Increase. grams. grams. grams. grams. cals. cals. Oto2 hours1 59 7 56 9 191 27 2 to 4 hours 64 12 69 22 181 17 4 to 6 hours 49 -3 46 -1 184 20 6 to 8 hours 51 -1 46 -1 169 5 Total . . . 223 15 217 29 725 69 finished eating mayonnaise, lettuce, and lemon 48 minutes after beginning of this period. Finally, to subdivide this particular experiment still further, the results obtained for the first four 2-hour periods with food — ?'. e., from 9 a. m. to 5 p. m.— are given in table 20; the basal values used are the average of those for the same period of time on the fasting days, and are given in table 21. On this basis it will be seen that there was a positive increase of 15 grams in the carbon-dioxide production in the four 2-hour periods following the ingestion of the oil, 29 grams in the oxygen consumption, and 69 calories in the heat production. Special attention is given here to the presentation of the results of this particular experiment on account of the rather remarkable con- tention of Gigon2 that, according to his experience, the ingestion of oil measurably depresses the metabolism. It is perhaps important to note that Gigon gave perfectly pure olive oil, while the oil in our experi- ment was mixed with a small proportion of lemon juice, egg yolk, and lettuce. While the two series of experiments are not perfectly compar- able, nevertheless it is of significance that the depression noted by Gigon is at variance with the increment, slight though it is, shown in our results. JSee statistics for fasting and food d;iys, Dec. 5-6, 1906, on p. 251. 'Gigon, Arch. f. d. ges. Physiol., 1911, 140, p. 509. BASAL METABOLISM. 69 TABLE 21. — Basal metabolism of A. H. M., 9 a. m. to 6 p. m., December 3 and 4, 1906. Observation and date. Duration. 9 a. m. to 11 a. m. 11 a. m. to 1 p. m. 1 p. m. to 3 p. m. 3 p. m. to 5 p. m. Average. 1906. Carbon dioxide: Dec. 3 9 a. m. to 5 p. m . . grams. 57 grams. 53 grams. 52 grams. 50 grams. 53 Dec. 4 .... 9 a. m. to 5 p. m . . 56 51 50 46 61 Average 57 52 51 48 52 Oxygen : Dec. 3 9 a. m. to 5 p. m . . 54 41 44 50 47 Dec. 4 9 a. m. to 5 p. m . . 51 45 48 42 47 Average 53 43 46 46 47 Heat: Dec. 3 Dec. 4 . . 9 a. m. to 5 p. m . . 9 a. m. to 5 p. m . . cals. 181 183 cals. 167 168 cals. 151 cals. 152 145 cals. 163 165 Average 182 168 151 149 164 In the 24-hour experiments thus far considered, the base-line was determined immediately prior to the ingestion of the food. In the 24- hour experiment with the subject A. H. M., February 2 to 3, 1906, in which crackers and milk were taken, such basal values were not avail- able. A base-line obtained in an experiment on November 21 to 23, 1905, was therefore used, this being the nearest date on which a fasting value was obtained for this subject. Although the detailed discussion of the fasting experiment with A. H. M., December 3 to 5, 1906, shows that we have available still another fasting value, it did not seem desir- able to average the two values for a base-line for this particular food experiment, inasmuch as the metabolism of this subject in the fall of 1905 was distinctly different from that in the latter part of 1906. The results of the food experiment with A. H. M., February 2 to 3, 1906, are given in table 22, together with the average values for the fasting experiment of November 21 to 23, 1905. The values obtained on the two fasting days agree closely; the average heat production was 1,755 calories. With the ingestion of the crackers and milk, which had a total fuel value of about two-thirds of the daily requirement, the heat production was increased 239 calories, with a corresponding increase in the carbon-dioxide production a.nd oxygen consumption. Here again it is extremely difficult to account for the unusually large increment. While it would normally be ascribed solely to the ingestion of the food, it is so at variance with the results obtained in almost all of the other experiments that one must question the reliability of the base-line. This experiment is an admirable illustration of the unsatisfactory use of 24-hour periods, particularly when there is a considerable interval 70 FOOD INGESTION AND ENERGY TRANSFORMATIONS. of time between the determination of the basal value and that deter- mined after the ingestion of food. TABLE 22.— A. H. M., February 2-8, 1906. (24-hour periods, 7 a. m. to 7 a. m.) Crackers and milk:1 Amount, 1,150 grams; nitrogen, 7.34 grams; total energy, 1,314 calories. Fuel value: Total, 1,250 calories; from protein, 15 per cent; from fat, 39 per cent; from carbohydrates, 46 per cent. Carbon dioxide. Oxygen. Heat. Date. Nitrogen in urine. Total. Increase. Total. Increase. Total. Increase. Without food: grams. grams. grams. grams. grams. cals. cols. Nov. 21-22, 1905. . . 9.11 535 . . . 517 . . 1,729 . . . Nov. 22-23, 1905 . . . 13.05 524 527 1,781 Average 11.08 530 ... 522 1,755 With food: Feb. 2-3, 1906 "12.38 679 149 602 80 1,994 239 'The food was eaten mostly in three portions, at 9 a. m., 1 p. m., and 6 p. m. Soda crackers and graham crackers were used with the milk. 2For period 6h15m a. m. Feb. 2 to 7 a. m. Feb. 3. GENERAL CONCLUSIONS REGARDING USE OF 24-HOUR PERIODS. From the foregoing discussion of the results of the experiments made on the 24-hour basis, it is seen that serious objections may properly be raised to this type of experiment, even though on first consideration the method may seem theoretically desirable. Experience with fast- ing men, both at Wesleyan University and in the Nutrition Labora- tory,1 has demonstrated that the metabolism progressively decreases as the fast continues. In the fast studied at the Nutrition Laboratory, in which accurate graphic records of the activity were obtained, this decrease in the fasting metabolism occurred with considerable uni- formity at least 31 days, accompanied by a proportional loss in body- weight. In view of the steady loss in weight, it seems illogical to use values for a base-line which were determined under such conditions, particularly if the values are not compared on the basis of per kilogram of body-weight or per square meter of body-surface. Furthermore, the depression in the metabolism due to fasting is abnormal, for evidently we have here a process entirely distinct from that due to the mere absence of food in the digestive tract. If we are to follow the contention of Johansson, we must consider the digestion of food and the daily body metabolism as two entirely independent processes, the body drawing continually upon its several depots for its immediate needs and the ingestion of food resulting in a separate process for replenishing these depots. At the time our studies of the 'Benedict, Carnegie Inst. Wash. Puh. No. 77, 1907, and No. 203, 191.5. BASAL METABOLISM. 71 basal metabolism begin (approximately 12 hours after the iugestion of food) , active digestion has ordinarily ceased and the body deposits are presumably still in a normal condition, with the usual liberal supplies of glycogen, fat, and protein. During the post-absorptive condition the body begins to draw upon these deposits, particularly the glycogen, and in approximately 2 to 4 days of fasting the labile glycogen supply is heavily depleted; thereafter the metabolism remains essentially a protein-fat katabolism until food is again taken. As a result of these heavy drafts upon body material during fasting, we have, after one or two days of fast, a condition which represents at least the beginning of inanition. It would appear, therefore, that as soon as the general nutritive condition of the body is seriously affected by a disturbance in the proportion of body materials, we pass outside the field of measure- ment of the basal metabolism for studies on the influence of food. It is well known that one of the first effects of the ingestion of food after long inanition is the replenishment of the reserves of body material, and there is excellent evidence that this replenishment is accomplished by processes materially different from those occurring during ordinary digestion. For the majority of experiments in which the effect of food is studied, a sharp differentiation between the post-absorptive condition and the beginning of inanition is unnecessary, but in certain of our experiments, especially those made in 24-hour periods, when the ingestion of food was 24, 36, 48, or even 60 and more hours after the last meal, we may have a condition of the body which distinctly approximates the first stages of inanition. The increment due to the ingestion of food would therefore be based upon abnormal values which would theoretically be somewhat lower than those ordinarily used for such studies. With so low a basal value, it frequently occurs that the stimulus of food simply compensates for the depressing influence of the previous fast and no increment in the metabolism is found. The effect obtained from the ingestion of food thus becomes a function of the duration of the fasting. For this reason the series of experiments in which the period of fasting was limited to two days are logically more satisfactory than those in which the subject fasted for a longer period. The greatest practical difficulty encountered in the use of the 24-hour method of experimenting was the fact that after one or two days of fasting the subjects were frequently unable to eat appreciable quanti- ties of food without distress. In the series of 2-day fasting experi- ments with college students at Wesley an University, the experimental plan included the ingestion of unusually large amounts of food on the third day for the purpose of obtaining maximum effects. To our surprise and disappointment, it was found in many cases that the sub- jects could not eat large amounts of the food, or, having eaten it, they experienced distress, this being particularly true when large quantities 72 FOOD INGESTION AND ENERGY TRANSFORMATIONS. of a single food or pure food substance were given. Accordingly, the most of our experiments were made with relatively small amounts of food, with a correspondingly small fuel value, this fuel value occa- sionally representing but one-half or two-thirds of the daily needs. It was only when the period was somewhat curtailed and the observa- tions confined to the night period that satisfactory base-lines could be obtained and the effect of the superimposed food definitely determined without the disturbing factor of the depression due to fasting. This latter plan of experimentation leads us naturally into the subdivision of the experimental day and a complete abandonment of the 24-hour method of experimenting. From the foregoing considerations the only conclusion that can be reached is that the 24-hour period does not lend itself to a sharply defined study of the influence upon metabolism of the ingestion of food — first, because the establishment of a suitable basal value is extremely difficult, since each day of fasting shows a lowered metabolism as the specific result of the fasting; and second, because it has been proved physiologically impossible for many subjects, after two days of fasting, to take large amounts of food. These large amounts are particularly desirable for studying the influence upon the metabolism of a special food substance, especially as the increment, which is frequently slight, must be included in the total measurements for the 24-hour period and would thus in some cases, either wholly or in part, escape obser- vation. This plan of experimentation thus defeats its own end, minimizing the effect of the food ingestion by a physiological reaction of the subject after fasting, and attenuating the frequently small incre- ment in the metabolism due to the stimulating action of the food materials. EXPERIMENTS OF APPROXIMATELY 8 HOURS. The unsatisfactory termination of the attempts to use the 24-hour period in studying the influence of the ingestion of food upon metabo- lism led to a rearrangement of the experimental plans and the substi- tution of shorter experiments in which the metabolism was studied during that section of the digestive cycle when the maximum digestive activity would normally be expected. The experimental period would thus begin at approximately 9 o'clock in the morning and continue for about 8 hours. CRITIQUE OF 8-HOUR METHOD. In the 8-hour periods it was easier for the subject to follow a pre- scribed routine, such as sitting quietly in a chair without major muscu- lar movement, than in the 24-hour periods. Furthermore, the uncer- tainty as to the length of time the subject slept was usually eliminated, BASAL METABOLISM. 73 as the experiments were made in the daytime, when the men were for the most part awake. Theoretically the 8-hour period experimental plan would have been very satisfactory if it had been possible for the subjects to sleep throughout the period and thus provide an ideal con- dition for measuring the quiescent metabolism. With many people there is a tendency to sleep after eating; our subjects, however, were nearly all young, many of them being college students; sleep after eating was therefore not a common experience; hence a uniformity in sleep could not be accepted as certain. These experiments were subdivided into 2-hour periods and in the Boston experiments into periods even shorter. There was therefore opportunity to secure information as to the time relations of the increase in the metabolism and possibly the maximum effect of the food. Many of the disadvantages found with the 24-hour plan apply, also, to the 8-hour method. The possible errors in the measurements are the same as with the longer periods, especially with the large chamber at Wesleyan University, but with the shorter periods thej^ assume more importance, since there is less opportunity for compensation and the total amounts are smaller. Furthermore, with the protein-rich diets, the total effect of the ingestion of food is not obtained, as it is unquestionably true that the stimulus frequently continues longer than 8 hours. During the 8-hour period only one or two meals can be given; the daily routine, with period of sitting or lying after food, must therefore be sacrificed. Finally, if we use as a basis of comparison the metabolism deter- mined in an 8-hour period without food, as was done in all of the Mid- dletown experiments considered in this section and in some of the Boston experiments, we must still rely upon the determination of the base-line on one day and the observation of the food period on a sub- sequent day. In the 24-hour experimental plan the periods usually succeeded one another without interval, with the subject under careful surveillance the entire time and with like muscular activity throughout the days compared. In comparison experiments with an 8-hour basal unit, a period of some 8 to 14 hours, and sometimes one or more weeks, may intervene between the fasting and food measurements. During this time the subject is not under supervision; the activity and possibly the diet are therefore not known. The influence of a previous diet, muscular activity, and psychical excitement is as yet too uncertain for us to assume with surety that the basal metabolism will be alike during the periods compared, for although there is a general agreement between experiments made in this way, the katabolism does not remain exactly the same from day to day, either with or without food. Even when we average the results of a large number of fasting experiments and deduct this average from the results obtained after food to find the increase in the metabolism due to the ingestion of food, the errors 74 FOOD INGESTION AND ENERGY TRANSFORMATIONS. introduced may amount to a considerable percentage of the whole increment. With large increments this possible difference in conditions would of course have less significance than with small increments. Con- sequently, while both the 24-hour and the 8-hour basal units permit reasonably satisfactory measurements of large increments in the metab- olism as a result of the taking of food, they are open to very serious objection when used for the measurement of small increments. DISCUSSION OF RESULTS OF 8-HOUR EXPERIMENTS WITHOUT FOOD. The 8-hour experiments were made with the respiration calorimeters at Wesleyan University, Middletown, Connecticut, and the Nutrition Laboratory, Boston, Massachusetts. Inasmuch as the Boston 8-hour experiments differed somewhat in plan from those made in Middle- town, the two groups of experiments will be discussed separately. Those carried out at Wesleyan University will first be considered, not only because they are first in chronological order, but also because the apparatus used and general technique, other than duration, were like those of the 24-hour experiments which have just been discussed. In the collection of the data a number of basal values were secured, ranging over a period of several weeks or months, and not infrequently a year or more. Hence this collection of basal data has special impor- tance as indicating the possibility of seasonal variation, and furthermore as showing the probable trend of the metabolism on any given day when the metabolism was measured in 4 to 6 consecutive 2-hour periods. The basal metabolism experiments only will be considered in this section; the results of the experiments with food will be given later in the discussion of the effect upon the metabolism of different classes of foods. MIDDLETOWN CALORIMETER EXPERIMENTS (8-HouR BASIS). The 8-hour plan was used successfully in a large number of experi- ments at Wesleyan University in which the basal metabolism was studied for approximately this period on one day and on a subsequent day the metabolism after the ingestion of food was found for a corre- sponding period. The increment due to the food was then determined by comparing the results obtained. Uniformity in the degree of muscular repose was even more important in these shorter experiments than it was in the 24-hour experiments, and it was necessary to reduce the muscular activity to a minimum so far as possible. The results of the experiments are given in tables 23 to 26. These tables show the experimental day divided into 2-hour periods, the data for the individual periods being placed according to the time the obser- vations were made. The experiments usually began about 9 a. m., BASAL METABOLISM. 75 and the values in the "first period" commonly represent the values obtained approximately in the period between 9 a. m. and 11 a.m. Averages are given for each period and also for each experimental day. The carbon-dioxide production and oxygen consumption are shown in two significant figures and the heat production in three significant figures. The weighings of the carbon-dioxide are accurate to the tenth of a gram, but as there is always an uncertainty in determining the residual amount of carbon dioxide in a chamber of so large a volume as TABLE 23. — Basal metabolism of A. L. L. at different times of day in calorimeter experiments, subject in sitting position. — Middlelown. (Values per 2 hours.) Date. Duration. First two hours.1 Second two hours. Third two hours. Fourth two hours. Fifth two hours. Sixth two hours. Average 1906. Feb. 7.... Feb. 9. ... Feb. 20. ... Apr. 3 ... Apr. 6 Carbon dioxide. 10hOOma.m. to 6hOOmp.m. 9 00 a.m. to 5 00 p.m . 8 45 a.m. to 4 45 p.m . 8 40 a.m. to 12 40 p.m. 1 15 p.m. to 9 15 p.m. gm. 48 47 48 48 gm. 46 47 45 50 gm. 46 45 48 45 gm. 48 47 46 gm. 46 gm. 43 gm. 47 47 47 49 45 1907. Apr. 20. ... May 4 ... Average (1906) 7h45ma.m. to 3h45mp.m. 8 15 a.m. to 4 15 p.m . 48 56 54 47 53 51 46 54 50 47 55 50 46 43 47 55 51 Average (1907) 55 52 52 53 53 1908. Feb. 7.... Feb. 9.... Feb. 20. ... Apr. 3. ... Apr. 6. ... Oxygen. 10hOOma.m. to 6hOOmp.m . 9 00 a.m. to 5 00 p.m . 8 45 a.m. to 4 45 p.m. 8 40 a.m. to 12 40 p.m . 1 15 p.m. to 9 15 p.m. 40 36 40 39 40 44 36 47 44 39 46 38 45 44 43 46 43 39 42 41 41 43 42 1907. Apr. 20 May 4. . . Average (1906) 7h45ma.m. to 3h45mp.m. 8 15 a.m. to 4 15 p.m. 39 49 45 42 48 43 42 43 45 48 40 43 39 42 48 43 Average (1907) 47 46 43 44 46 1906. Feb. 7.... Feb. 9. ... Feb. 20. ... Apr. 3 Heat. 10hOOma.m. to 6hOOmp.m . 9 00 a.m. to 5 00 p.m . 8 45 a.m. to 4 45 p.m . 8 40 a.m. to 12 40 p.m . cats. 164 162 151 147 cals. 145 145 148 147 cals. 140 142 150 cals. 150 147 163 cals. cals. cals. 150 149 153 147 Apr. 6. ... 1 15 p.m. to 9 15 p.m. 146 146 140 136 142 1907. Apr. 20. ... May 4. . . Average (1906) 7h45ma.m. to 3h45mp.m. 8 15 a.m. to 4 15 p.m. 156 169 2171 146 169 2160 145 178 2154 152 167 2148 140 136 148 171 2158 Average (1907) . . . 170 165 166 158 165 *The beginning of the "First two hours" was for this subject between 7h45m a. m. and 10 a. m 2Heat eliminated corrected for change in body-weight, but not for change in body-temperature 76 FOOD INGESTION AND ENERGY TRANSFORMATIONS. that of the Middletown calorimeter (approximately 5,000 liters), it seems permissible to record the results only to the nearest gram. With at least three of our subjects, A. L. L., A. H. M., and H. R. D., five or more basal values were obtained. (See tables 23, 24, and 25.) With both A. L. L. and A. H. M., difficulty was experienced in finding an average value, since with both subjects there appeared to be a dis- tinct variation in the metabolism as measured at different times. For example, with A. L. L., the basal values determined from February 7 to April 6, 1906, inclusive, were on an entirely different level from those found a year later. This is shown not only in the carbon-dioxide production, but also in the oxygen consumption and heat production. TABLE 24. — Basal metabolism of A. H. M. at different times of day in calorimeter experiments, subject in sitting position. — Middletown. (Values per 2 hours.) First Second Third Fourth Fifth Sixth Date. Duration. two two two two two two Average. hours.1 hours. hours. hours. hours. hours. 1906. Carbon dioxide. gm. gm. gm. gm. gm. gm. gm. Feb. 12. ... 9h30ma.m. to 5h30mp.m . . . 44 45 43 45 , . . . 44 Feb. 14. ... 9 00 a.m. to 5 00 p.m. . . 50 44 44 46 46 Average (1906) 47 45 44 46 45 1906. Nov. 22... 9h04ma.m. to 9h04mp.m . . . 54 51 51 49 48 47 50 1907. Mar. 6 ... 9h15ma.m. to 5h15mp.m. . . 52 51 49 54 52 Mar. 9 ... 9 00 a.m. to 5 00 p.m . . . 50 49 50 52 50 Average (1906-1907) . 52 50 50 52 48 47 51 1906. Oxygen. Feb. 12. ... 9h30ma.m. to 5h30mp.m. . . 37 39 41 43 40 Feb. 14. ... 9 00 a.m. to 5 00 p.m. . . 40 35 43 40 40 Average (1906) 39 37 42 42 40 1906. Nov. 22. .. 9h04ma.m. to 9h04mp.m . . . 48 44 45 42 . . 43 44 1907. Mar. 6... 9h15ma.m. to 5h15mp.m. . . 43 48 44 51 . . . . 47 Mar. 9... 9 00 a.m. to 5 00 p.m. . . 41 44 47 47 45 Average (1906-1907) . 44 45 45 47 43 45 1906. Heat. cals. cals. cals. cals. cals. cals. cals. Feb. 12. ... 9h30ma.m. to 5h30mp.m. . . 156 132 135 131 . . . 139 Feb. 14. ... 9 00 a.m. to 5 00 p.m . . . 163 146 131 138 145 Average (1906) 160 139 133 135 142 1906. Nov. 22... 9h04ma.m. to 9h04mp.m . . . 172 157 158 158 155 149 158 1907. Mar. 6... 9h15ma.m. to 5h15mp.m. . . 169 159 162 167 ... • • > 164 Mar. 9 ... 9 00 a.m. to 5 00 p.m . . . 167 162 159 168 164 Average (1906-1907) . 169 159 160 164 155 149 162 lThe beginning of the" First two hours" was for this subject between 9 a. m. and 9b 30™ a.m. BASAL METABOLISM. 77 Hence the values for 1906 and 1907 are averaged separately. The average carbon-dioxide production per two hours for A. L. L. during the spring of 1906 was 47 grams; a year later the average of two experi- ments showed 53 grams. Similar variations were observed in the oxy- gen consumption, the average value for 1906 being 42 grams, while that for 1907 was 46 grams. The average heat production was 148 calories in 1906 and 165 calories in 1907. TABLE 25. — Basal metabolism of H. R. D. at different times of day in calorimeter experiments, subject in sitting position. — Middletown. (Values per 2 hours.) First Second Third Fourth Fifth Sixth Date. Duration. two two two two two two Average hours.1 hours. hours. hours. hours. hours. 1906. Carbon dioxide. gm. gm. gm. gm. gm. gm. gm. Feb. 6.... 9h46ma.m. to 5h46mp.m . . 46 47 50 47 47 Feb. 10. ... 9 15 a.m. to 5 15 p.m. . 48 48 45 47 . . 47 Apr. 4. ... 8 37 a.m. to 12 37 p.m. . 48 45 46 Apr. 10... . 1 00 p.m. to 9 00 p.m . . . . 47 47 48 48 48 Apr. 20 1 30 p.m. to 9 00 p.m . . 244 48 46 48 47 Average 47 47 47 47 47 48 47 Oxygen. Feb. 6. ... 9h46ma.m. to 5h46mp.m . . 42 39 48 40 42 Feb. 10.... 9 15 a.m. to 5 15 p.m. . 39 40 40 44 41 Apr. 10. ... 1 00 p.m. to 9 00 p.m.. . . 39 44 42 44 42 Apr. 20 1 30 p.m. to 9 00 p.m. . 241 44 48 44 44 Average 41 40 42 43 45 44 42 Heat. cals. cals. cals. cals. cals. cals. cals. Feb. 6. ... 9h46ma.m. to 5h46mp.m . . 146 137 148 142 , , , 143 Feb. 10. ... 9 15 a.m. to 5 15 p.m. . 150 144 141 137 . . . 143 Apr. 4. ... 8 37 a.m. to 12 37 p.m. . 155 141 148 Apr. 10.... 1 00 p.m. to 9 00 p.m . . 159 156 138 149 151 Apr. 20. ... 1 30 p.m. to 9 00 p.m. . 2148 150 140 134 143 Average . 150 141 149 146 139 142 146 *The beginning of the "First two hours" was for this subject approximately between 8h30m a. rn. and 9h45m a. m. Calculated to 2-hour basis; measured in period of lj hours. With the subject A. H. M. the basal metabolism determined on 2 days in the middle of February 1906 showed a distinctly lower value than the basal metabolism determined in the fall of 1906 and spring of 1907. Thus, the average carbon-dioxide production for February 1906 was 45 grams, the oxygen consumption was 40 grams, and the heat production was 142 calories, while the average values for the three experiments in the period from November 22, 1906, to March 9, 1907, was 51 grams for the carbon-dioxide production, 45 grams for the oxy- gen consumption, and 162 calories for the heat production. It is thus clear that with these two subjects we have a variation of at least 10 per cent, as shown by these duplicate experiments. 78 FOOD INGESTION AND ENERGY TRANSFORMATIONS. With both subjects there was an increase in weight between the two groups of experiments. With A. L. L. the weight in 1906 averaged 67 kilograms and in 1907 it averaged 73.4 kilograms, this increment in weight being approximately proportional to the increase noted in the metabolism. With A. H. M. the weight increased from 63.8 kilograms to 66.2 kilograms; this slight increase was by no means proportional to the increase in the metabolism. Although the values for the metab- olism have not been presented on the basis of per kilogram of body- weight or per square meter of body-surface, it is obvious that with this latter subject the metabolic level was distinctly higher in the second group of experiments than in the first group. Accordingly, in deter- mining the increment in the metabolism with food, it is impossible to use an average of these basal values for comparison and we must resort to a selection of data from the experiments made nearest in point of time to the food experiments. A general examination of tables 23, 24, and 25 shows that there is a distinct tendency for the 2-hour values to diminish as the day pro- ceeds. Not infrequently the value for the first period of the day is somewhat higher than the others. Inasmuch as nearly all of our exper- iments were planned on the four 2-hour period basis, this point demands special consideration. The general picture for the two subjects A. L. L. and A. H. M. (see tables 23 and 24) shows a definite though slight tendency for the metabolism to decrease as the day progresses, this being especially noticeable in the fifth and sixth periods. On the other hand, the average carbon-dioxide values for H. R. D. (table 25) are constant, while the oxygen values show, if anything, a slight in- crease; the values for the heat production are irregular. It should be remembered, however, that in several instances, and particularly with H. R. D., the average values for the later periods are not derived from values obtained on the same day as the averages for the preceding periods, and hence they do not represent consecutive 2-hour periods in all instances. Furthermore, while there are variations in individual periods, it is the average of all these values that is being discussed, and these averages indicate truthfully the general trend of the metabolism. The values for the subjects H. C. K, Dr. R., E. H. B., A. W. W., and H. B. W. (see table 26) usually show more constancy in the first four periods of the day, although in a number of cases those for the fourth period are high, especially for the heat production. The average basal metabolism for each subject is recorded in table 27, in which are given the average values for the body-weight, the carbon dioxide produced, oxygen consumed, heat produced, and nitro- gen excreted in the urine per 2-hour period. The nitrogen values are included in this table as an indication of the probable protein katabo- lism in the experiments. In no instance was the diet controlled prior to the experiment, although usually no food had been taken for at least BASAL METABOLISM. 79 TABLE 26. — Basal metabolism at different times of day in calorimeter experiments, subjectt in sitting position. — Middletown. (Values per 2 hours.) Subject and observation. Date. Duration. First two hours.1 Seconc two hours. Third two hours. Fourth two hours. Average. H. C. K. Carbon dioxide. Oxygen . 1906. May 3 May 3 9h05ma.m. to 5h05mp.m.. 9 05 a.m. to 5 05 p. in 0m. 52 47 gm. 47 42 gm. 52 51 gm. 53 47 gm. 51 47 Heat May 3 9 05 a.m. to 5 05 p.rn cals. 175 cals. 161 cals. 152 cals. 167 cals. 164 DR. R. Carbon dioxide. Oxygen 1907. Feb. 20 Feb. 20 8h58ma.m. to 4h58mp.m . . 8 58 a.m. to 4 58 p.m . . gm. 46 gm. 49 43 gm. 48 gm. 50 48 gm. 48 45 Heat Feb. 20 8 58 a.m. to 4 58 p.m. . cals. -147 cals. 2141 cals. 2146 cals. 2148 cals. 2146 E. H. B. Carbon dioxide. Mar. 7 Mar. 13 9h01ma.m. to 5h01mp.m. . 8 55 a.m. to 4 55 p.m . . gm. 60 59 gm. 57 55 gm. 58 60 gm. 58 57 gm. 58 58 Average 60 56 59 58 58 Oxygen Mar. 7 9h01ma.m. to 5h01mp.m . . 47 49 50 51 49 Mar. 13 8 55 a.m. to 4 55 p.m. . 48 41 53 46 47 Average 48 45 52 49 48 Heat Mar. 7 9h01ma.m. to 5h01mp.m . . cals. 183 cals. 179 cals. 173 cals. 182 cals. 179 Mar. 13 8 55 a.m. to 4 55 p.m . . 193 169 185 169 179 Average 188 174 179 176 179 A. W. W. Carbon dioxide. Mar. 15 Mar. 21 9h05ma.m. to 6h05mp.m . . 8 29 a.m. to 4 29 p.m. . gm. 48 50 gm. 55 51 gm. 50 49 gm. 50 48 gm. 61 50 Average 49 53 50 49 50 Oxygen. . Mar. 15 9h05ma.m. to 5h05mp.m 40 42 43 43 42 Mar. 21 8 29 a.m. to 4 29 p.m. . 39 42 40 40 40 Average 40 42 42 42 41 Heat. . Mar. 15 9h05ma m to 5h05mp m cals. 166 cals. 164 cals. 154 cals. IRQ cals. IRQ Mar. 21 8 29 a.m. to 4 29 p.m. . 165 158 140 144 162 Average 166 161 147 149 155 H. B. W. Carbon dioxide. Mar. 22 Apr. 4 Apr. 26 8h31ma.m. to 4h31mp.m. . 8 32 a.m. to 4 32 p.m. . 8 05 a.m. to 12 05 p.m. . gm. 59 55 59 gm. 59 54 56 gm. 58 53 gm. 56 53 gm. 58 54 57 Average 58 56 56 55 56 Oxygen Mar 22 8h31ma m. to 4h31mp m 48 50 51 51 50 Apr. 4 Apr. 26 8 32 a.m. to 4 32 p.m . . 8 05 a.m. to 12 05 p.m. . 47 51 44 50 45 49 46 60 Average 49 48 48 50 49 Heat Mar. 22 8h31ma.m. to 4h31mp.m cals. 2190 cals. 2171 cals. 2172 cals. 2171 cals. 2176 Apr. 4 Apr. 26 8 32 a.m. to 4 32 p.m . . 8 05 a.m. to 12 05 p.m . . 160 166 158 166 159 154 158 166 Average 172 165 166 163 167 lThe beginning of the "First two hours" was for the subjects in this table between 8b05m a. m. and 9h05m a. m. 'Heat eliminated corrected for change in body-weight but not for change in body-temperature. 80 FOOD INGESTION AND ENERGY TRANSFORMATIONS. TABLE 27. — Summary of average values for basal metabolism determined for subjects in sitting position in calorimeter experiments. — Middletown. (Amounts per 2 hours.) Subject. Average body-weight without clothing. Carbon dioxide. Oxygen. Heat. Nitrogen1 excreted in urine. A. L. L., 1906. . 1907. . A. H. M., 1906 . 1907. H. R. D. kilos. 67.0 73.4 63.8 66.2 58 2 grams. 47 53 45 51 47 grams. 42 46 40 45 42 cats. 148 165 142 162 146 gram. } 0.72 | .94 75 H. C. K . 73 6 51 47 164 82 Dr. R 60 4 48 45 2146 69 E. H. B 72.1 58 48 179 89 A. W. W 57.7 50 41 155 65 H. B. W 62.4 56 49 167 85 'Includes all nitrogen values obtained with these subjects for the periods in which the baaal metabolism was determined and on any first day of fasting. See table 28. 2Heat eliminated corrected for change in body-weight, but not for change in body-temperature. TABLE 28. — Nitrogen excreted in urine during experiments ivithout food. (Amounts per 2 hours.) Subject. Date. Amount. Subject. Date Amount. A. L. L Apr. 27, 1904 grams. 11.03 H. R. D. Dec. 5-6, 1905 grams. ll 10 Dec. 16, 1904 l.S3 Apr. 4, 1906 .52 Feb. 20, 1906 . 78 Apr 10-11 1906 70 Apr. 3, 1906 .65 Apr. 20, 1906 .69 Anr 6 IQOfi QA Apr. 20, 1907 . . .71 Average 75 Mav 4 1Q07 Dr R Feb 20 1907 69 72 EH H Mar 7 1Q07 CB A. H. M... . Nov. 21-22, 1905 l.7Q Mar. 13, 1907 .89 Fph 14 IQOfi 04 Nov. 22, 1906 1 08 Average .89 T)r*r> t—A IQOfi O FT/> Mar. 6, 1907.. . 1.06 A. W. W . . . Mar. 15, 1907 .55 Mar. 9, 1907 1.06 Mar. 21, 1907 .75 Average 94 Average .65 H. C. K Nov. 24-25 1905 1 78 H. B. W Mar. 22, 1907 85 May 3 1906 85 Apr. 4, 1907 82 Apr 26 1907 87 eo Average . . 85 'Benedict, Carnegie last. Wash. Pub. No. 77, 1907. Excepting the results with A. L. L. April 27 and Dec. 16, I'.tOI, these values taken from Pub. No. 77 represent the 24 hours of the first fasting flay. ^Determined in 24 hours of first day of fast. BASAL METABOLISM. 81 12 hours. These average nitrogen values are also shown in table 28, together with all of the available nitrogen values for the individual experiments included in tables 23, 24, 25, and 26. For the subjects A. L. L., A. H. M., H. C. K., and H. R. D., these values are supple- mented by other values drawn from experiments not discussed in this publication. The detailed results in table 28 show, particularly with H. R. D. and A. L. L., a much wider variation than would normally be expected. Thus on the second day with H. R. D. April 4, 1906, the nitrogen excreted was less than half that excreted on December 5-6, 1905. A still more striking variation is that on April 6, 1906, with A. L. L., which is approximately one- third of that found on April 27, 1904, with the same subject. In general the variations from the average value are not sufficiently great to affect seriously the computations of the energy transformations in which it is desirable to apportion the energy between the protein and the other constituents of the metabolism. GENERAL CONCLUSIONS REGARDING 8-HouR EXPERIMENTS IN MIDDLE-TOWN. The general conclusion may thus be drawn, from an inspection of the data in tables 23, 24, 25, and 26, that for the first four 2-hour periods in the daytime, beginning at approximately 9 o'clock, with the subject in the post-absorptive condition, there is usually a somewhat high value in the first period of the day, followed by a reasonable constancy in the next three periods; in the few values recorded for the fifth and sixth periods, a tendency is shown for the metabolism to decrease with two subjects and to increase with a third subject. There is, of course, a possibility that the increases noted in some of the values during the later periods were due to restlessness of the subject as a result of the long sojourn in the chamber. On the other hand, there was certainly no external muscular activity of sufficient moment which would justify us in assuming that the measurement of the metabolism was vitiated in this way. In using the data for basal values in the measurement of the influence of the ingestion of food, it is evident that when major increments are to be expected one may disregard the slight variations noted throughout the day in these tables and consider that the metabolism is essentially constant. This is in line with the earlier interpretation of basal values given by us in a previous publication,1 which were obtained in duplicate experiments during the daytime, but occasionally during the sleeping period. A close agreement was there noted in the average values for the carbon-dioxide production, oxygen consumption, and heat pro- duction for the experiments compared. It should be remembered, however, that the average values referred to were for fairly long periods, i. e., from 6 to 12 hours, and in at least one instance, for 4 'Benedict and Carpenter, Carnegie Inst. Wash. Pub. No. 126, 1910, p. 107, table 45. 82 FOOD INGESTION AND ENERGY TRANSFORMATIONS. \ days. While these values do indicate, therefore, a constancy in the metabolism for periods of this length, they give no evidence as to the possibilities of variations from period to period, such as those shown in tables 23, 24, 25, and 26. In considering the values for the metabolism given in these basal tables, it should be remembered that the subjects were allowed the restricted freedom of the respiration chamber. It was impossible to require them to remain absolutely quiet or to assume a definite posi- tion for the period of 8 to 12 hours during which they were under obser- vation. The muscular activity was kept at a minimum, however, and every attempt was made to have it uniform from day to day. While we believe that the values given represent a higher metabolism than the strictly basal metabolism of the individuals studied — i. e., the metab- olism with muscular repose and without food in the stomach— we feel that our use of them for comparison with the results of the subsequent food experiments is permissible, in the absence of less contaminated data, inasmuch as the routine and degree of muscular activity on the food days were very similar to those on the daj^s when the basal metabolism was obtained. BOSTON CALORIMETER EXPERIMENTS (8-HouR BASIS). In the experiments on the 8-hour plan in Boston, both the chair calorimeter and the bed calorimeter were used for measuring the metabolism. In the chair calorimeter, which was the first calorimeter constructed in the Nutrition Laboratory, the subject remained com- fortably seated in an arm chair throughout an experiment. The total volume of the air in the chamber was approximately 1,400 liters; the air space and body activity were therefore much more restricted than in the Middletown calorimeter, in which the chamber had a volume of approximately 5,000 liters, affording opportunity for considerable movement. In the chair calorimeter the water bottles and urine bottles were conveniently placed near the subject and it was unneces- sary to rise from the chair for their use ; there was, however, some minor muscular activity, such as the motions accompanying the reading of a book, and similar movements. The actual activity in the chair- calorimeter experiments was very considerably less than that in the calorimeter experiments in Middletown, save when the latter experi- ments were made during the periods from 11 p. m. to 7 a. m. with the subject asleep in bed. The chamber of the bed calorimeter was even smaller than that of the chair calorimeter, being approximately 950 liters in volume. The subject lay upon a cot and it was impossible for him to sit up or to move very much except to turn the body from side to side. The food aperture was never opened during an experiment. Occasionally / BASAL METABOLISM. 83 the subject drank water, and urine collections were sometimes made. During the greater part of the time the subject read quietly or slept. The results of the experiments with the bed calorimeter may thus con- sistently be used as evidence of an approximate basal metabolism— i. e., the minimum metabolism with nearly complete muscular repose and in the post-absorptive condition. All of the Boston experiments were made with the subject in the post- absorptive condition (12 hours after food). Furthermore, it was pos- sible in these experiments to obtain a graphic record of the muscular activity by means of a pneumograph fastened around either the chest or the thighs and connected with a tambour outside the chamber. Inasmuch as the air volume of the two calorimeters used in Boston was smaller than that of the Middletown apparatus and the subject was considerably quieter, the measurements could be made with a higher degree of accuracy, especially as the activity was controlled by means of the graphic record. It was thi*s possible to subdivide the experi- ment into shorter periods and to obtain values per hour or per three- quarters of an hour instead of for 2 hours, as with the Middletown experiments. While the duration of the Boston experiments was approximately the same as that of the Middletown experiments considered in this section, the general plan was changed in that the basal metabolism was first determined for a number of periods, then the food was given, and the experiment was continued for the remainder of the 8 hours. The basal metabolism and the metabolism after food were thus deter- mined on the same day in continuous measurements. This plan was followed with nearly all of the food materials studied except beefsteak. Certain of the experiments were continued for periods longer than 8 hours in order to obtain further information as to the probable varia- tion from hour to hour. In many instances observations were made with the same subject at intervals for many months or even years; a hint could thus be obtained as to the possibility of seasonal or yearly variations. The first extended experiment in which the chair calorimeter was used was that made with J. R., December 3, 1908, although this appa- ratus had been tested in shorter experiments prior to this date. The results of this experiment, together with those of five other experiments with the same subject, are given in table 29. In this and the succeeding tables, the day is divided into hour periods, the results obtained in the individual periods being placed in the table according to the time the observations were made. Average values are also given both for the experimental periods and for the values obtained in the individual periods in all of the experiments. In considering the latter averages, it should be borne in mind that some of the individual values were determined several months or years apart. 84 FOOD INGESTION AND ENERGY TRANSFORMATIONS. TABLE 29. — Basal metabolism of J. R. at different times of day in chair-calorimeter experiments. — Boston. (Values per hour.) Date. Observation and duration. First hour.1 Second hour. Third hour. Fourth hour. Fifth hour. Sixth hour. Average. 1908. Dec. 3 Dec. 17 1910. Mar. 21 Carbon dioxide. 9h12ma.m. to 3u12mp.m 9 01 a.m. to 3 01 p.m .... 8 49 a.m. to 10 49 a.m am. 28.0 27.5 26 0 am. 28.5 27.5 26 0 am. 26.5 28.5 am. 25.5 27.5 gm. 25.5 27.5 am. 25.5 26.5 am. 26.5 27.5 26 0 May 5 8 38 a.m. to 10 38 a.m. . 27.0 26.5 27.0 May 10 8 37 a.m. to 10 37 a.m. . 27.0 28.0 27.5 May 13 8 57 a.m. to 10 57 a.m 25.5 26.5 26 0 Average 27.0 27.0 27.5 26.5 26.5 26.0 27.0 1908. Dec. 3 Dec. 17 1910. Mar. 21 Oxygen. 9h12ma.m. to 3h12mp.m. . . . 9 01 a.m. to 3 01 p.m 8 49 a.m. to 10 49 a.m .... 24.0 24.0 21.5 23.5 22.5 21.0 23.0 24.0 23.0 24.5 22.5 24.5 23.5 23.0 23.5 24.0 21.0 May 5 8 38 a.m. to 10 38 a.m. . . . 22.0 23.5 23.0 Mav 10 8 37 a.m. to 10 37 a.m. . . . 24.0 24.0 May 13 8 57 a.m. to 10 57 a.m 20.0 23 0 21.5 Average 22.5 23.0 23.5 24 0 23.5 23.5 23.0 190S. Dec. 3 Dec. 17 1910. Mar. 21 Heat. 9h12ma.m. to 3h12mp.m 9 01 a.m. to 3 01 p.m. . . . 8 49 a.m. to 10 49 a.m cats. 274 78 79 cals. 275 88 81 cals. 272 81 cals. 276 89 cals. 273 77 cah. 273 82 cals. 274 83 80 May 5 8 38 a.m. to 10 38 a.m .... 274 272 273 May 10 8 37 a.m. to 10 37 a.m. . . . 271 -72 272 May 13 8 57 a.m. to 10 57 a.m . 282 278 280 Average 76 78 77 83 75 78 77 'The beginning of the "First hour" was for this subject approximately between 8h30m a. m. and 9h15m a. m. 2Heat eliminated corrected for change in body-weight, but not for change in body-temperature. The carbon-dioxide production with this subject was remarkably constant, as shown by the figures in both sets of averages. Individual variations may be noted, however, the values being in two cases as high as 28.5 grams per hour and in several instances as low as 25.5 grams. On the whole, the agreement shows rather remarkable uniformity, not only from month to month but from hour to hour. The same uniformity is, in general, shown in the averages for the oxygen consumption. The range in the individual values is from 20 grains to 24.5 grams. Considerable variation appears in the values for the heat production. Thus in the fourth hour a value as high as 89 calories was found, while in another instance we have a value as low as 71 calories. When the average values alone are considered, the variations from hour to hour are found to be quite small, with the single exception of the average for the fourth hour. In general, this subject produced 77 calories of heat per hour. BASAL METABOLISM. 85 TABLE 30. — Basal metabolism of F. M. M. at different times of day in chair-calorimeter experiments. — Boston. (Values per hour.) Date. Observation and duration. First hour.1 Second hour. Third hour. Fourth hour. Fifth hour. Sixth hour. Seventh hour. Average. 1908. Dec. 9 Dec. 14 Dec. 18 Dec. 22 Dec. 29 Carbon dioxide. 8h36ma.m. to 2h36rap.m . . 1 1 02 a.m. to 4 02 p.m . . 9 15 a.m. to 3 15 p.m . . 8 40 a.m. to 2 40 p.m. . 10 00 a.m. to 4 00 p.m gm. 27.0 24.5 24.5 0m. 24.5 27.0 24.5 28.5 gm. 26.0 26.0 25.5 25.5 26.0 gm. 24.0 26.0 25.0 24.5 26.0 gm. 24.5 29.0 25.0 23.5 24.0 gm. 24.0 26.5 27.0 25.0 23.5 gm. 24.5 25.0 gm. 25.0 26.5 25.6 24.6 25 5 1909. Jan. 6 Jan. 11 Apr 8 8 50 a.m. to 2 50 p.m. . 9 06 a.m. to 3 06 p.m . . 10 24 a m. to 1 24 p.m 25.5 26.0 26.0 22.5 23.5 24.5 24.0 25.0 25.0 24.0 21.5 25.0 23.5 25.5 23.0 25.5 24.0 23.5 1910. Jan 31 9 30 a m to 1 1 30 am 29 0 27.0 28.0 Feb 2 851am to 1051 am 27 5 27 5 27.6 Feb 8 9 38 am to 1 1 38 am 24 5 26 5 25.6 Feb. 19 9 03 a.m. to 11 03 a.m . 26 0 25.0 25.5 Average 26 0 25.5 25.5 24.5 25 0 25.0 25.0 25.5 1908. Dec. 9 Dec. 14 Dec. 18 Dec. 22 Dec. 29 Oxygen. 8h36ma.m. to 2h36mp.m . . 11 02 a.m. to 4 02 p.m. . 9 15 a.m. to 3 15 p.m. . 8 40 a.m. to 2 40 p.m. . 10 00 a.m. to 4 00 p.m . . 23.5 19.5 20.0 19.0 26.5 19.5 24.0 22.5 25.5 23.5 23.0 23.0 19.5 22.5 24.0 23.0 22.0 23.0 24.5 22.5 20.5 23.0 20.0 23.5 24.5 22.0 20.0 22.0 22.0 21.0 23.5 23.6 21.5 22.5 1909. Jan. 6 Jan. 11 Apr. 8 8 50 a.m. to 2 50 p.m. . 9 06 a.m. to 3 OG p.m . . 10 24 a.m. to 1 24 p.m 23.0 22.0 23.0 19.5 20.5 21.5 22.5 20 5 25.5 21.0 21.0 23.5 22.0 22.5 20.0 23.0 21.0 20 5 1910. Jan 31 9 30 a.m. to 11 30 a.m 24 5 23.5 24 0 Feb. 2 8 51 a.m. to 10 51 a.m. . 22.0 24.5 23 6 Feb. 8 9 38 a.m. to 11 38 a.m. 22.0 23.0 22 5 Feb. 19 9 03 a.m. to 11 03 a.m. 22.5 22 5 Average 22.0 22.5 23 0 22.5 22.5 22 0 22.0 22 6 1908. Dec. 9 Dec. 14 Dec. 18 Dec. 22 Dec. 29 Heat. 8h36ma.m. to 2h36mp.m . . 11 02 a.m. to 4 02 p.m. . 9 15 a.m. to 3 15 p.m. . 8 40 a.m. to 2 40 p.m . . 10 00 a.m. to 4 00 p.m. cats. 87 85 268 cafe. 84 82 269 280 cals. 72 282 68 270 276 cals. 74 271 81 270 278 cals. 273 281 79 271 275 cals. 275 268 79 270 264 cals. 268 27l' calf. 77 '74 79 =70 J74 1909. Jan. 6 Jan 11 8 50 a.m. to 2 50 p.m. . 9 06 a.m. to 3 06 p.m 87 85 78 80 77 82 70 85 76 71 71 82 74 Apr. 8 10 24 a.m. to 1 24 p.m . . 278 278 280 279 1910. Jan. 31 9 30 a.m. to 11 30 a.m. 282 279 281 Feb. 2 8 51 a.m. to 10 51 a.m 277 278 S78 Feb. 8 9 38 a.m. to 11 38 a.m. . 283 281 J82 Feb. 19 9 03 a.m. to 11 03 a.m. . 276 282 279 Average 81 80 75 76 77 71 70 77 'The beginning of the " First hour" was for this subject approximately between 8h30m a. m. and 9h30™ a. m. JHeat eliminated corrected for change in body-weight, but not for change in body-temperature. 86 FOOD INGESTION AND ENERGY TRANSFORMATIONS. With the subject F. M. M., a larger number of prolonged experiments were made, many of them continuing for 6 hours. The results are given in table 30. An examination of the averages indicates again a remarkable uniformity both from hour to hour and from day to day. Individual variations, however, should not be lost sight of, as they show that it is always possible to obtain both large and abnormally small values. Strictly speaking, if the lowest value is accurately measured, that alone should be regarded as the absolute basal metabo- lism. The general picture of the basal metabolism is, however, not unlike that reported in the earlier observations by us,1 and leads us to the general conclusion that the average carbon-dioxide production per hour is independent of the time of day and does not vary, at least with this subject, inside of a period of about 14 months. Somewhat wider fluctuations appear in the individual periods for the oxygen consumption and yet the average values are remarkably constant. As with J. R., the variations in the values for the heat production in the individual periods are considerable. While the average values do not show so close an agreement as do those for the carbon-dioxide produc- tion and the oxygen consumption, yet they indicate that this man produced 77 calories per hour in the chair calorimeter. It should be stated that this subject was somewhat unsatisfactory in that it was difficult for him to remain perfectly quiet. Probably the lowest measurements of the metabolism here do not indicate the basal metabo- lism of this man, as he was in the sitting position, but they do represent the minimum amount of extraneous muscular activity. For purposes of comparison with the values obtained for the metabolism after food, however, their use is justified, as the two series of determinations were made under like conditions. An extended series of measurements of the basal metabolism, most of them of only 2 hours' duration, was made with J. J. C. Both the chair calorimeter and the bed calorimeter were used in this series. This man was also a very unsatisfactory subject, owing to his tendency to fall asleep, the degree of muscular repose thus being very irregular. Even with this subject the average values remain remarkably constant, especially for the carbon-dioxide production. It should be borne in mind, however, that the values from the third to the fifth periods are represented by only a single experiment. The measurements of the heat output for this man were extremely unsatisfactory, as no meas- urements of the body-temperature were obtained ; hence the determina- tions for the heat have not been corrected for changes in this factor. By reference to table 31 it is seen that on the average this subject produced in the chair calorimeter 78 calories per hour, a rather remark- able agreement with the subjects J. R. and F. M. M. Benedict and Carpenter, Carnegie Inst. Wash. Pub. No. 126, 1910, pp. 171, 184, and 194, tables 69, 73, and 77. BASAL METABOLISM. 87 TABLE 31. — Basal metabolism of J. J. C. at different times of day in chair-calorimeter experiments. — Boston. (Values per hour.) Date. Observation and duration. First hour.1 Second hour. Third hour. Fourth hour. Fifth hour. Average. 1909. \pr T Carbon dioxide. 101'56ma m. to Ih56mp.m . . . gm. gm. gm. 26.0 gm. 25 0 gm. 25 5 gm. 25 5 1910. Mar 4 9 07 am. to 11 07 a.m. 25.5 26.5 26 0 Mar 12 9 30 am to 1 1 30 a.m 23.5 24.5 24 0 Mar 22 9 21 a m to 11 21 a.m 26 5 23.5 25 0 Mar. 25 8 14 a.m. to 10 14 a.m 26.0 24.5 25.5 Apr. 29 8 59 a.m. to 10 59 a.m 27.0 25.5 26.0 Mav 9 9 31 a.m. to 11 31 a.m 25.5 23.5 24 5 May 12 9 02 am. to 11 02 a.m 26 5 24.0 25 0 Mav 18 8 56 a.m. to 10 56 a.m 24.0 22.5 23.0 May 31 9 15 a.m. to 11 15 a.m 25.5 26.0 26.0 1911. Jan. 10 9 08 a.m. to 11 23 a.m 227.0 227.0 225.0 26.0 Jan. 13 8 56 a.m. to 10 26 a.m 226.5 227.5 27.0 Jan 17 9 24 a.m. to 11 42 a.m 225 . 5 227.5 225.5 26.0 Average 26.0 25.0 25.5 25 0 25 5 25 5 1909. Apr 7 Oxygen. 10''56ma.m. to Iu56mp.m 20.5 20.5 23.0 21 5 1910. Mar 4 9 07 a.m. to 11 07 a.m 21.0 23.0 22 0 Mar 12 9 30 am. to 11 30 a.m 20 5 20.5 20 5 Mar 22 9 21 am to 11 21 a.m 24 0 21 0 22 5 Mar. 25 8 14 a.m. to 10 14 a.m 21.5 20.5 21.0 Apr. 29 8 59 a.m. to 10 59 a.m 24.0 20.5 22.0 May 9 9 31 a.m. to 11 31 a.m. . 24.5 18.5 21 5 May 12 9 02 a.m. to 11 02 a.m 21 0 18.5 20 0 May 18 8 56 am to 10 56 a.m 17 5 20 5 19 0 May 31 9 15 a.m. to 11 15 a.m 21.0 19.5 20.5 1911. Jan. 10 9 08 a.m. to 11 23 a.m =22.0 ?24.5 221.0 22.5 Jan. 13 8 56 a.m. to 9 41 a.m ... 222.5 22.5 Jan. 17 9 24 a.m. to 11 42 a.m 224.5 223.0 24.0 Average 22.0 20.5 21.5 20.5 23.0 21.5 1910. Mar. 12 Heat. 9h30ma.m. to Ilh30ma.m ca/s. 71 cals. 79 cals. cals. cafe. cals. 75 Mar. 22 9 21 a.m. to 11 21 a.m 386 380 383 Mar. 25 8 14 a.m. to 10 14 a.m 380 379 379 Apr. 29 8 59 a.m. to 10 59 a.m . ... 74 78 76 May 12 9 02 a.m. to 11 02 a.m. . . 383 375 379 May 18 8 56 a.m. to 10 56 a.m 73 74 74 Mav 31 9 15 a.m. to 11 15 a.m 82 75 79 1911. Jan. 10 9 08 a.m. to 11 23 a.m 277 280 -77 878 Jan. 13 8 56 a.m. to 10 26 a.m 278 271 375 Average 78 77 77 78 JThe beginning of the "First hour" with the chair calorimeter was approximately between 8h15m a. m. and 9h30m a. m. 'Calculated to hour basis; measured in period of 45 minutes. The heat values on Jan. 10 and 13, 1911, are heat eliminated corrected for change in body-weight, but not for change in body-temperature. JHeat eliminated corrected for change in body-weight, but not for change in body-temperature. 88 FOOD INGESTION AND ENERGY TRANSFORMATIONS. TABLE 31 (continued). — Basal metabolism of J. J. C. at different times of day in bed- calorimeter experiments. — Boston. (Values per hour.) Date. Observation and duration. First hour.1 Second hour. Third hour. Fourth hour. Fifth hour. Sixth hour. Average. 1910. Oct 27 Carbon dioxide. 9h08ma m. to 12h08mp.m 0m. 22 5 0m. 22 0 am. 23 0 am. gm. gm. gm. 22 5 Oct 31 9 22 am to 12 22 p m 23 5 23 0 22 5 23 0 Nov. 3 9 35 a.m. to 11 35 a.m. . 22.5 22.0 22.5 Nov. 8 9 46 a.m. to 12 18 p.m. -22 . 0 22 0 22.0 Nov 10 12 53 p m. to 2 53 p.m 22 0 23 0 22.5 Nov 15 12 34 p m. to 3 50 p.m 322 5 22 5 322 0 22.5 Average 23.0 22 5 22 5 22.5 22.5 22.5 22.5 Oct 27 Oxygen, 9h08ma.m. to 12bOSmp.m 20 5 18 5 19 0 19.5 Oct. 31 9 22 a.m. to 12 22 p.m 18 5 19 0 17 5 18.5 Nov 3 9 35 a m to 1 1 35 a m 19 5 18 5 19 0 Nov. 8 9 46 a.m. to 12 18 p.m. 217.5 18.5 18.0 Nov. 10 12 53 p.m. to 2 53 p.m 19.0 19.0 19.0 Nov. 15 12 34 p.m. to 3 50 p.m. . . 19.5 319.0 19.6 Average. . 19 5 18.5 18.5 19.5 19.0 19.0 Oct. 27 Heat. 9h08ma.ni. to 12b08mp.m cals. 46S cals. 468 cals. 467 cals. cals. cals. cals. 468 Oct. 31 9 22 a.m. to 12 22 p.m 459 462 463 461 Nov. 3 9 35 a.m. to 11 35 a.m. 4 66 465 466 Nov. 8 Nov. 10 9 46 a.m. to 12 18 p.m. . . 12 53 p.m. to 2 53 p.m 264 464 465 467 464 466 Nov. 15 12 34 p.m. to 3 50 p.m 365 465 368 466 Average 464 465 465 465 465 468 465 'The beginning of the "First hour" with the bed calorimeter was approximately between 9 a. m. and 9b30™ a. m. Calculated to hour basis; measured in period of Ih32m. Heat not corrected for change in body-temperature. 'Calculated to hour basis; measured in period of Ih8m. Heat not corrected for change in body-temperature. 4Heat eliminated corrected for change in body-weight, but not for change in body-temperature. The bed-calorimeter experiments with J. J. C. were even more unsat- isfactory than those with the chair calorimeter, as the subject showed a decided tendency to go to sleep and at times a definite although not extended activity. Under these conditions the metabolism was meas- urably less than the values obtained with the chair calorimeter. The carbon-dioxide production from hour to hour was remarkably uniform, especially when the average values alone are considered. Aside from the values for the first period the heat measurements again show constant average values; the general average for this apparatus was 65 calories per hour, a value some 13 calories less than that found with the chair calorimeter. This value undoubtedly represents very closely the basal metabolism of J. J. (\, although, as stated above, even the values obtained with the chair calorimeter may justifiably be used as a base- line for studying the influence of the ingestion of food in experiments BASAL METABOLISM. 89 made with the same apparatus. Both basal values find their subse- quent use in a consideration of the results of the food experiments. The series of experiments with L. E. E., in which only the chair calorimeter was used, extended over a relatively short period of time— i. e., from March 14 to May 11, 1910. (See table 32.) The average values for both the carbon-dioxide production and the oxygen consump- tion agree very well with those found with the subjects previously considered. Those for the heat production show a striking disagree- ment with each other, the high value of 81 calories being found for the first hour, while a low value of 68 calories is found in the third hour of one experiment. It is probable that these variations in the values for heat output are due to the fact that they have not been corrected for changes in body-temperature, as these measurements were not made; hence the heat values correspond to heat elimination rather than to heat production. TABLE 32. — Basal metabolism of L. E. E. at different times of day in chair-calorimeter experiments. — Boston. (Values per hour.) Date. i Observation aud duration. First hour.1 Second hour. Third hour. Average. 1910. Mar. 14 Carbon dioxide. 9h23n'a.m. to Ilb23ma.ni . . gm. am. 28.5 gm. 25.5 gm. 27.0 Mav 3 8 40 am to 10 40 am 25 0 24 5 25 0 May 11 8 31 a.m. to 10 31 a.m 25 0 24.0 24 5 Average 25.0 25.5 25.5 25.5 Mar. 14 Oxygen. 9h23ma.m. to Ilh23ma,.m 23.0 21.5 22.0 May 3 8 40 a.m. to 10 40 a.m . . 22.0 21.0 21.5 May 11 8 31 a.m. to 10 31 a.m 22.0 21.5 21.5 Average . . . . 22.0 22.0 21.5 21.5 Mar. 14 Heat. 9h23ma.m. to Ilh23ma.m cals. cals. 272 cals. 268 cats. 270 May 3 8 40 a.m. to 10 40 a.m 281 274 278 Mav 11 8 31 a.m. to 10 31 a.m 281 279 280 Average 281 275 268 276 'The beginning of the "First hour" was for this subject approximately between 8h30m a. in. and 9h30m a. m. 2Heat eliminated corrected for change in body-weight, but not for change in body-temperature. Another subject, V. G., who was measured in both the chair calo- rimeter and the bed calorimeter, was not temperamentally adapted for experimentation with such a fine point at issue as the influence of the ingestion of food. The basal values obtained with the chair calorimeter show larger variations from hour to hour than have thus far been noted with any of the subjects; indeed, the measurements of the heat output were lost in the experiment of January 21. (See table 33.) Measure- 90 FOOD INGESTION AND ENERGY TRANSFORMATIONS. TABLE 33. — Basal metabolism of V. G. at different times of day in calorimeter experiments. — Boston. (Values per hour.) Date. Observation and duration. First hour.1 Second hour. Third hour. Fourth hour. Average. 1911. CHAIR CALORIMETER. Carbon dioxide. / 9h07ma.m. to 9h52ma.m gm. gm. gm. gm. gm. Tan 2 >230 . 0 30.0 30.0 \11 22 a.m. to 12 15 p.m / Ian 21 8 55 am to 10 25 am 228.5 229.5 29.0 Average. . f 29.5 29.5 30.0 29.5 Oxygen. / 9h07ma.m. to 9h52ma.m Jan 2 >224 . 0 26.0 25.0 \11 22 a.m. to 12 15 p.m / Tan 21 8 55 a m to 10 25 a m 222.0 228 5 25.5 Average . 23.0 28.5 26.0 25.5 Heat. ( gi>07ma m. to 9h52ma.m cols. cals. cals. cals. cals. Tan 2 >286 379 '83 \11 22 a m to 12 15 p.m / 1910. Oct 24 BED CALORIMETER. Carbon dioxide. 9h39ma m. to 12h39mp.m gm. gm. 23.0 gm. 24.5 gm. 24.0 gm. 24.0 Oct 26 9 52 am to 12 52 p.m. . 424.5 424.0 24.5 Nov 4 9 26 am to 11 56 a.m 423.5 24.0 24.0 Nov 7 9 01 a.m. to 11 06 a.m 24.0 25.0 24.5 Dec 19 9 12 a.m. to 11 27 a.m 226.5 224.5 226.0 25.5 Average . . ... 25.5 24.0 24.5 24.0 24.5 Oct 24 Oxygen. 9h39ma.m. to 12h39mp.m 20.0 22.5 21.0 21.0 Oct 26 9 52 a.m. to 12 52 p.m 419.0 420.0 19.5 Nov 4 9 26 am to 11 56 a.m . . . 420.5 20.5 20.5 Nov 7 9 01 am to 11 06 am 19 0 19 0 19.0 Dec 19 9 12 a.m. to 11 27 a.m 220.5 223.0 222.5 22.0 Average 20.0 20.5 21.5 21.0 20.5 Oct. 24 Heat. 9h39ma.m. to 12h39mp.m cats. cals. 361 cals. 369 cals. 568 cals. »66 Oct 26 9 62 a.m. to 12 52 p.m 466 467 367 Nov. 4 9 26 a.m. to 11 56 a.m 465 368 367 Nov 7 9 01 a.m. to 11 06 a.m . 364 364 364 Dec. 19 9 12 a.m. to 11 27 a.m 265 268 367 Average 364 364 3C8 368 366 'The beginning of the "First hour" for this subject was approximately between 9 a. m. and 9h15m a. m. Calculated to hour basis; measured in period of 45 minutes. The heat values are heat elimi- nated corrected for change in body-weight, but not for change in body-temperature. 'Heat eliminated corrected for change in body-weight, but not for change in body-temperature. Calculated to hour basis; measured in period of 1J hours. Heat not corrected for change in body-temperature. BASAL METABOLISM. 91 ments of the body-temperature were practically impossible with this subject and hence the use of the heat values for comparison with those obtained after food is questionable. The average results of the bed- calorimeter experiments show no great fluctuation, even for the heat output. With this subject, also, the average values found with the chair calorimeter are perceptibly higher than those found with the bed calorimeter. The subject T. M. C., thoroughly aware of the importance of uniform muscular activity, gives us values in chair-calorimeter experiments that are probably as accurate and consistent as can be expected with any subject. (See table 34.) They show but few deviations from the normal value for both the carbon-dioxide production and the oxygen consumption. As no measurements of the body-temperature were made, the usual variations in the measurements of the heat output appear. The average results show a remarkable constancy in the metabolism from hour to hour. The period of experimentation was short, being only from January 3 to January 12, 1911, and no marked differences are found from day to day. The low metabolism noted in the whole series is in large part explained by the small body-weight of the subject. Four other subjects, A. G. E., C. H. H., Dr. H., and D. J. M., were studied in the chair calorimeter for two 1-hour periods; the results of these few experiments are also given in table 34. As a rule, the values obtained show the usual uniformity from hour to hour. TABLE 34. — Basal metabolism at different times of day in chair-calorimeter experiments. — Boston. (Values per hour.)1 Subject and observation. Date. Duration. First hour.2 Second hour. Third hour. Fourth hour. Aver- age. T. M. C. Carbon dioxiJe. 1911. Jan. 3 Jan. 7 Jan. 12 8h25ma.m. to 9h58ma.m . . . f 8 43 a.m. to 10 15 a.m . . . \11 45 a.m. to 12 30 p.m. . . 8 55 a.m. to 10 25 a.m . . . gm. 19.0 J19.0 19.5 gm. 19.0 18.5 18.5 gm. gm. 18.0 gm. 19.0 18.5 19.0 Average 19.0 18 5 18.0 19.0 Oxvgen Jan. 3 8h25ma.m. to 9h58ma.m . . 17.5 18 0 18 0 Jan. 7 Jan. 12 f 8 43 a.m. to 10 15 a.m . . . \11 45 a.m. to 12 30 p.m. . . 8 55 a.m. to 10 25 a.m . . . J16.fi 16.5 17.0 17.5 17.0 17.0 17.0 Average 17.0 17.5 17.0 17.5 Heat Jan. 3 8h25ma m. to 9h58ma m cals. 366 cals. 360 cals. cals. cals. 363 Jan. 7 Jan. 12 f 8 43 a.m. to 10 15 a.m. . . \11 45 a.m. to 12 30 p.m. . . 8 55 a.m. to 10 25 a.m . . . J356 366 355 358 356 356 '62 Average 363 358 356 360 'Values for T. M. C. calculated to hour basis; measured in periods of 45 minutes. 2The beginning of the "First hour" was approximately between 8h30m a. m. and 9 a. m. 3Heat eliminated corrected for change in body-weight but not for change in body-temperature. 92 FOOD INGESTION AND ENERGY TRANSFORMATIONS. TABLE 34. (continued). — Basal metabolism at different times of day in chair-calorimeter ex- periments.— Boston. (Values per hour). Subject and observation. Date. Duration. First hour.1 Second hour. Third hour Fourth hour. Aver- age. A. G. E. 1911. Tan ^ 8h47ma m to 10h17ma.m . gm. 224.5 gm. 224.0 gm. gm. gm. 24.5 Oxvgen Jan 23 8 47 a.m. to 10 17 a.m. . . 222.0 221.0 21.6 Heat Tan ^ 8 47 am. to 10 17 a.m. . cols. •72 cals. 271 cals. cals. cals. 372 C. H. H. [•in 18 8h58ma m to 10h28ma.m gm. 222.0 gm. 222.0 gm. gm. gm. 22.0 Tnn 18 8 58 am. to 10 28 a.m . 220.0 219.5 20.0 Heat Jan 18 8 58 a.m. to 10 28 a.m . . . cals. 260 cals. 260 cals. cals. cals. 360 DH. H.4 Carbon dioxide 1910. Feb 14 9h24ma.m. to Ilh24ma.m Qm. gm. 23.0 gm. 21.5 gm. gm. 22.0 Feb 17 9 31 a.m. to 11 31 a.m 21.5 21.5 21.5 Average ... 22.0 21.5 22.0 Oxvgen. Feb 14 9h24ma.m. to Ilh24ma.m. . . 20.5 19.5 20.0 Feb 17 9 31 a.m. to 11 31 a.m 20.0 20.5 20.5 Average. . . . . 20.5 20.0 20.5 D. J. M. Oarbon dioxic'e Mar 23 9h33ma.m. to Ilh33ma m Qm. gm. 25 5 gm. 25 5 gm. gm. 25.5 June 3 9 37 a.m. to 11 37 a.m. . . 25.5 24.5 25.0 June 7 9 21 a.m. to 11 21 a.m. . . 25.5 26.0 26.0 Average 25.5 25 5 25.5 Oxvgen Mar. 23 9h33ma.m. to Ilh33ma.m. . . 20.5 22.0 21.0 June 3 9 37 a.m. to 11 37 a.m. . . 20.5 20.5 20.5 June 7 9 21 a.m. to 11 21 a.m. . 21.5 20.5 21.0 Average 21.0 21.0 21.0 Heat. Mar 23 9h33ma.m. to Ilh33ma.m. . cals. cals. 368 cals. 372 cals. cals. 370 June 3 9 37 a.m. to 11 37 a.m. 76 76 76 June 7 9 21 am. to 11 21 a.m 382 378 380 Average 75 75 75 JThe beginning of the "First hour" was for the subjects in this table approximately between S^O"1 a. m. and 9 a. m. 2C'alculated to hour basis; measured in period of 45 min. The heat values for subjects A. G. E., and C. H. H., are heat eliminated corrected for change in body-weight, but not for change in body-temperature. 3Heat eliminated corrected for change in body-weight, but not for change in body-temperature. 4The heat measurements for the experiments with this subject were technically defective. A summary of the values for the basal metabolism found with the subjects of the Boston calorimeter experiments is given in table 35. With two subjects we have values obtained with both the chair and bed calorimeters, which show that the metabolism in the chair calo- rimeter is perceptibly higher than that in the bed calorimeter. The difference is so much greater than that which would commonly be expected, and also greater than that shown in an earlier report from BASAL METABOLISM. 93 this laboratory,1 that it must be considered as due not merely to a difference in body position but also to an admittedly somewhat more liberal muscular activity in the chair calorimeter as compared with that in the bed calorimeter. Undue stress must not be laid upon the rather remarkable agreement in the values for the heat output with the subjects J. R., F. M. M., L. E. E., D. J. M., and J. J. C., in the experi- ments with the chair calorimeter or upon the extraordinarily low values obtained with C. H. H. and A. G. E., for the fact that the body-temper- ature measurements were lacking in many of the experiments plays an mportant role in the interpretation of these values. TABLE 35. — Summary of average values for basal metabolism determined for subjects in calorimeter experiments. — Boston. (Amounts per hour.) Subject. Calorim- eter. Average body-weight without clothing. Carbon dioxide. Oxygen. Heat. Nitrogen1 excreted in urine. J. R Chair . . kilos. 68 3 grams. 27 0 grams. 23 0 cals. 77 grams. 0 46 F. M. M Chair . 60 2 25 5 22 5 77 43 J. J. C Chair 64 8 25 5 21 5 78 1 Bed 63.5 22.5 19.0 265 .40 L. E. E Chair 59 5 25 5 21 5 276 52 V. G Chair 55 8 29 5 25 5 283 \ Bed 53.3 24.5 20.5 266 .35 T. M. C.. . A. G. E Chair Chair. 47.7 56 4 19.0 24 5 17.5 21 5 260 272 .41 42 C. H. H Chair 54 8 22 0 20 0 260 3 36 DR. H Chair .... 66 3 22 0 20 5 .32 D. J. M Chair 58 1 25 5 21 0 75 51 includes all nitrogen obtained with these subjects for the periods in which the basal metab- olism was determined and during any other periods without food. (See table 36.) 2Heat eliminated corrected for change in body-weight, but not for change in body-temperature. 3Subject was without food in first 3 hours of the 5 hours covered by each sample included in this average. Sucrose was given at the end of 3 hours. For the purpose of indicating the protein metabolism of these Boston subjects, we have included in table 35 average values for the nitrogen excretion per hour, not only for the calorimeter experiments, but for other experiments not included in this publication. The values from which these averages are drawn are given in table 36. No marked variation is found with the different individuals, the same subject usually having approximately the same nitrogen excretion per hour under the conditions of measurement employed. It is rarely that such con- trasts are noted as that in the results for V. G., with whom a very small excretion of nitrogen occurs on November 21, while 3 days earlier almost the maximum amount is found. That this corresponds to an actual difference in the protein katabolism is by no means definitely assured from these figures, for the difficulty of completely emptying the bladder, especially in the case of young and untrained subjects, is well known to practiced experimenters. 'Emmes and Riche, Am. Journ. Physiol., 1911, 27, p. 406. 94 FOOD INGESTION AND ENERGY TRANSFORMATIONS. TABLE 36. — Nitrogen excreted in urine during experiments without food. (Amounts per hour.) Subject and date. Amount. Subject and date. Amount. Subject and date. Amount. 1908. J. R. Dec. 3 ... Dec. 17. .. 1909. Feb. 25... Mar. 20... Apr. 27 ... Apr. 29... May 1 ... May 6 ... May 12 ... May 15 ... May 18. .. May 21 ... May 29 ... 1910. May 5 ... May 10. .. Average . . . 1908. P.M. M.Dec. 9... Dec. 14. .. Dec. 18 ... Dec. 22. .. Dec. 29 ... 1909. Jan. 6.... Jan. 11.... Jan. 12 Jan. 22 Feb. 24. ... Apr. 8 1910. Jan. 31 Feb. 8.... Feb. 19. ... Average. . . 1909. L. E. E. Jan. 8.... Apr. 28. ... Apr. 30. .. May 3 ... May 7 ... May 10. .. May 13. .. May 20 ... May 22. . . June 1 ... June 9 ... June 16. . . Oct. 16.... gram. 0.37 .46 .46 .45 .46 .46 .49 .38 .55 .47 .49 .45 .55 .44 .44 1910. L. E. E. Mar. 7 (con.) Mar. 14 Mar. 19 Mar. 29 May 3 June 7 June 11 July 1 Nov. 26 Nov. 29 Dec. 3 Dec. 9 Average 1909. J. J. C. Jan. 27 (con.) Feb. 2 Mar. 3 Mar. 6 Mar. 6 Mar. 16 Apr. 7 1910. Feb. 5 Feb. 15 Feb. 18 Feb. 24 Mar. 4 Mar. 15 Mar. 18 Mar. 22 Mar. 25 Mar. 31 Apr. 4 Apr. 7 Apr. 29 May 6 May 9 May 12 June 6 June 8 June 10 June 13 Oct. 27 Oct. 31 Nov. 3 Nov. 6 Nov. 8 Nov. 10 Nov. 15 Nov. 22 1911. Jan. 10 gram. 0.49 .56 .52 .73 .51 .52 .66 .49 .44 .57 .45 .46 1911. J. J. C. Jan. 13 Jan. 17 Jan. 30 Feb. 1 Apr. 25 Average 1910. V. G. Oct. 24 Oct. 26 Nov. 4 Nov. 7 Nov. 18 Nov. 21 Dec. 19 1911. Jan. 2 Jan. 5 Jan. 21 Feb. 6 Feb. 15 Mar. 11 Average 1909. T. M. C. Feb. 4 Mar. 23 1910. Feb. 7 Feb. 23 Mar. 23 Mar. 26 May 16 May 25 June 2 June 8 June 20 June 24 July 12 Nov. 14 Nov. 16 1911. Jan. 3 Jan. 7 Jan. 12 Average 1910. A. G. E. Mar. 24 Mar. 28 Apr. 2 Apr. 6 gram. 0.60 .43 .50 .28 .33 .40 0.46 t .32 .32 .25 .49 .18 .32 .52 .32 .27 .28 .41 .37 .52 0.42 .29 .63 .38 .40 .40 .38 .38 .24 .37 .42 .47 .41 .46 .23 .41 .31 .49 .46 .40 .38 .26 .34 .48 .47 .60 .57 .45 .47 .37 .31 .32 .30 .41 .38 .59 .46 0.44 .63 .37 .35 .28 .33 .36 .46 .63 .46 .39 .54 .45 .54 .35 0.53 .49 .39 .44 .55 .45 .40 .32 .44 .49 .35 .40 .39 .36 .45 .36 .25 .28 .43 0.50 .62 .46 .45 .47 .48 .39 .52 .54 .53 .66 .48 .42 .41 0.35 .45 .43 .43 BASAL METABOLISM. 95 TABLE 36 (continued). — Nitrogen excreted in urine during experiments without food. (Amounts per hour.) Subject and date. Amount Subject and date. Amount Subject and date. Amount 1910. A. G.E.Apr. 9... (con.) May 19. .. May 27.. . May 31.. . June 3 ... June 13. .. July 2... 1911. Jan. 23 ... Average. . . gram. 0.41 .43 .45 .47 .49 .47 .33 .28 1911. C. H. H. May 10 May 23 Average 1910. DR. H. Feb. 14 Feb. 17 Average gram. !0.34 '.38 1910. D. J. M. Mar. 21 Mar. 23 Mar. 25 Mar. 30 Apr. 8 June 3 June 7 Average gram. 0.59 .65 .47 .32 .70 .49 .45 J.36 0.33 .30 .51 .32 .42 'Subject was without food in first 3 hours of the 5 hours covered by the sample in each case. Sucrose was given at the end of 3 hours. GENERAL CONCLUSIONS REGARDING 8-HouR EXPERIMENTS IN BOSTON. With the shortening of the experimental period, the distinction between heat production and heat elimination becomes of considerable consequence. In the 24-hour experiments it was found that the heat production and heat elimination were essentially identical — that is, that the body-temperature as determined by rectal measurements was practically the same each morning at 7 o'clock when the experimental day ended. While the correctness of this assumption as a generaliza- tion may fairly be questioned, nevertheless very considerable differ- ences in body-temperature may actually appear and yet not affect the calculation of the total heat production when based on the 24-hour unit. With short periods, on the other hand, temperature fluctuations may normally be expected. It has been demonstrated that there are ordi- narily variations of 1° to 2° C. in the normal rectal temperature, the minimum appearing from 3 to 5 a. m., and the maximum in the late afternoon. Even during short periods of rest there may be consid- erable fluctuation in the body-temperature. Consequently, as the experimental period is shortened, there is an increasing danger of possible error in the measurements of the heat production owing to either a storage of heat in the body, as shown by an increase in the body-temperature, or a loss of heat, as indicated by a fall in the body- temperature. To obtain the true heat production, the values for this storage or loss should be added to or deducted from the values obtained for the heat actually eliminated during the period. This question is of special significance when the attempt is made to compare the heat production and the gaseous exchange — in other words, to compare the direct and indirect calorimetry — the difficulties lying for the most part in securing a proper measurement of the body- 96 FOOD INGESTION AND ENERGY TRANSFORMATIONS. temperature. Many inconsistencies that appear at first sight in the results of these experiments, as, for instance, those with L. E. E. (table 32) , may properly be ascribed to erroneous measurements of the body-temperature or to the lack of such measurements. At about the time these experiments were made special attention was devoted to the measurement of heat production and the descrip- tion of a special apparatus for measuring the body-temperature deep in the rectum was published.1 It has been impracticable in all sub- sequent researches to take advantage of this method of measurement, and yet experience in this laboratory, as well as elsewhere, has shown that heat elimination as measured by the respiration calorimeter can have but little significance without a definite knowledge of the very considerable change in the body-temperature that may accompany a normal or physiological experiment and is quite likely to accompany observations on pathological cases. If we make a general study of the metabolism data obtained in these Boston experiments, the results may be summed up as follows: As a rule, the average values for the gaseous metabolism for each subject show uniformity, although at times there is more or less variation in the individual values. Owing, probably, to the fact that the body-tem- perature measurements were lacking or defective, there is frequently considerable variation in the heat output, although even here the values do not lack uniformity in some cases. With the two subjects who were studied in both the chair calorimeter and the bed calorimeter, lower values were invariably found with the bed calorimeter, this being due to the greater degree of muscular repose. It should be noted that the criterion for uniformity is a plus or minus variation of 5 per cent — that is, if the values for the carbon dioxide or the oxygen are within 1 gram of each other on the 20 to 25 gram basis, they are considered reasonably uniform. Hence we must admit at the outset the possibility of variations in the individual periods of at least plus or minus 5 per cent. This is important to note in any subsequent use of these values in determining the influence of the ingestion of food, for frequently the effect of the ingestion of food may be not much out- side this limit. Accordingly this basis of experimentation for food experiments, while favorable when a large effect of digestion is to be expected, is still of doubtful value when the subtler effects are studied, as they may be entirely lost sight of. We see no reason, however, why the results of these experiments should not, with intelligent appreciation of their defects, still be used for comparison with the results of experiments made under identically the same experimental conditions after the ingestion of food. One major criticism of so using these values may be made, in that while Benedict and Slack, Carnegie Inst. Wash. Pub. No. 155, 1911. BASAL METABOLISM. 97 the temperature curve of the normal body may be reasonably uniform when no food is taken, it is quite likely that the ingestion of food may produce a somewhat rapid rise in temperature which, if not measured accurately, would still further vitiate the calculation of the values for the heat production. It is thus seen that it will be necessary to confine the major discussion of the influence of the ingestion of food upon metabolism to its effect upon the respiratory exchange and the indirect calorimetry computed therefrom, using the grosser heat meas- urements as subsidiary evidence. SHORT-PERIOD EXPERIMENTS. An examination of the literature (see pages 10 to 46) shows that many of the researches have been carried out with short periods ranging from 2 hours to 10 or 15 minutes; the majority of the experiments were made in 15-minute periods. In our study of the metabolism after food a large proportion of the basal metabolism experiments were likewise made with these short periods. CRITIQUE OF THE SHORT-PERIOD METHOD. This method is particularly adapted for experiments with a respira- tion apparatus with which the gaseous metabolism may be determined and the heat output computed from the results. Such experiments are carried out with considerably less expense and the use of intricate calorimetric apparatus is avoided. Furthermore, comparable values for the metabolism may be obtained on the same day; thus one may be certain of a specially determined and reliable base-line each day, with accurate determinations of body-temperature, pulse rate, and respira- tion rate. With both the 24-hour period and the 8-hour period, various time- consuming observations must be made and much duplicate data secured before a satisfactory average is obtained. With the short- period base-line, values may be quickly obtained. Indeed, the results of one or two periods may be rejected on account of extraneous mus- cular activity of some definite nature, and a true base-line may be found from the average of the other periods with more constant results. To avoid possible activity in the rest periods, it has been the excellent custom in Johansson's laboratory in Stockholm to alternate the periods of complete rest with periods of moderate activity and not to insist upon the tedium of an arbitrarily imposed complete muscular rest for any great length of time. After two or three periods without food have been obtained with closely agreeing results, and the constancy of the base-line established for that day, food may be given the subject and a series of observations made for from 1 to 6 hours, or even longer. With 15-minute periods 98 FOOD INGESTION AND ENERGY TRANSFORMATIONS. it is possible to make an observation practically every 30 minutes. The course of the metabolism after the taking of the food can thus be closely followed and a satisfactory curve obtained showing the imme- diate effect, the maximum increment, and the gradual cessation of the excess heat production. The short-period method is thus more espe- cially fitted for studying small variations in metabolism and particu- larly the rapidly occurring and disappearing changes. Although sufficient material is obtained by this method of measure- ment to draw a graphic picture of the metabolism, the conditions are still not ideal, as the measurements are not continuous and small varia- tions and possible compensation may thus be lost, especially if the intervals between periods are lengthened from any cause. This method of determining the metabolism for comparison purposes is further open to criticism in that the assumption must be made that the metabolism remains constant throughout the experimental day, whereas the results may be affected by a daily rhythm or variation. The question may be fairly asked : When no food is taken, is the metab- olism the same at 3 p. m. as at 9 a. m.? In other words, if a base-line is determined at 9 a. m., food is given at 10 a. m., and the influence of the food is followed until 3 or 4 p. m., can it be assumed that the incre- ment noted at 4 p. m. above the base-line found at 9 a. m. is due exclu- sively to the influence of food, or is it due in part to a daily rhythm? Johansson found in his experiments, which were carried out with pre- cautions to maintain absolute muscular repose, that the time of day had but little or no influence upon the carbon-dioxide excretion.1 In considering the results of our experiments made by the short-period method, this question of constancy in the basal metabolism from hour to hour may be discussed intelligently, for a large amount of data is available from which conclusions may be drawn. DISCUSSION OF RESULTS OF SHORT-PERIOD EXPERIMENTS. Aside from a few experiments in which the Tissot apparatus was used,2 the universal respiration apparatus3 was employed exclusively for the short-period experiments. The experiments usually began between 8 and 9 a. m. and continued until noon, and sometimes later; the periods as a rule varied but little from 15 minutes in length. In some instances the experiment was 18 periods in length, but the ma- jority were from 5 to 6 periods long. The data for all of the subjects with whom experiments of five or more periods have been made have been collected and tabulated; the Johansson, Skand. Arch. f. Physiol., 1898, 8, p. 103. Magnus-Levy likewise states that the time of day has no influence upon the metabolism. (Magnus-Levy, Arch. f. d. ges. Physiol., 1894, 55, p. 32.) 2Tissot, Journ. de physiol. et de pathol. gen., 1904, 6, p. 688. 'Benedict, Am. Journ. Physiol., 1909, 24, p. 345; Deutsch. Arch. f. klin. Med., 1912, 107, p. 156. See, also, p. 202 of this monograph. BASAL METABOLISM. 99 results obtained with over 30 subjects are thus available for compari- son. With several subjects the experiments were made at intervals during a period of five or even six years, but with the majority they were made in a period of approximately two months or even two weeks. An abstract of similar data, which includes nearly all of the subjects with whom we are dealing in this publication, has been given in a previous paper from this laboratory.1 Emphasis was there laid upon the variations in the average maximum values for the oxygen con- sumption, using the average minimum value for a basis. Inasmuch as it is important to note the actual variations which may be observed in a long series of experiments of this kind, the data will be considered in more detail in this publication. As it would be impracticable to print all of the material obtained, three typical subjects have been selected and the carbon-dioxide pro- duction and oxygen consumption per minute for the individual periods with these subjects have been tabulated. The data for the other subjects are given in abstract. In the tables showing the detailed results, the day has been subdivided into half-hour periods and the data for the individual 15-minute periods of the experiment placed according to the time the observations were made. The values given under "first period" commonly represent those obtained in the experi- mental periods which occurred between 8 and 8h30m a. m. At the bottom of the tables are given the average values for each 30-minute period throughout the series, thus indicating the average course of the metabolism throughout the day. The minimum and the maximum values for each period are also given and the mean variations of the individual values from the averages. In the extreme right-hand column the averages for the individual experiments are placed, show- ing the course of the metabolism throughout the months or years of the study. In studying the results given in these tables, emphasis should be laid only upon the average values and no particular significance given to single values like the maximum and minimum data. This is in accord- ance with the custom of this laboratory, as such values are liable to technical errors and physiological variations which must necessarily creep into experiments as complicated as these. The average values for the day are olrawn from at least two results and usually three or more, while those for consecutive periods are computed from 5 to 42 periods. It should furthermore be remembered that the data for the oxygen consumption give a more logical basis for discussion than those ob- tained for the carbon-dioxide elimination. This is due to the remark- able influence upon the carbon-dioxide production of the character of the previous diet,2 the large variations in the calorific equivalent of Benedict, Journ. Biol. Chem., 1915, 20, p. 263, table 4. 2Benedict and Higgins, Am. Journ. Physiol., 1912, 30, p. 217. 100 FOOD INGESTION AND ENERGY TRANSFORMATIONS. carbon dioxide with varying respiratory quotients, and the possibility of an over- ventilation of the lungs accompanied by an excessive carbon- dioxide production. EXPERIMENTS WITH H. L. H. The most extensive series of experiments was obtained with Mr. H. L. Higgins, who was long connected with the experimental work of the Nutrition Laboratory. The first experiment with this subject was on May 23, 1910, and the last on June 2, 1915; although not made at regular intervals, the observations were reasonably well distributed over this period of about five years. Confining our discussion first to the carbon-dioxide values and considering the influence upon them of the time of day and their variation in the consecutive periods, we find that the carbon-dioxide production per minute shows considerable variation from hour to hour in the individual experiments. (See table 37.) Differences as large as 20 c.c. or more are occasionally noted, this corresponding to an approximate variation of 10 per cent. Thus in the experiment of September 24, 1911, there was a difference between the first and second periods of 26 c.c. and between the first and fourth periods of 31 c.c., or nearly 15 per cent of the average value for the day, while the values for January 13, 1912, show a difference between the second and third periods of 30 c.c., again about 15 per cent of the average for the day. The average values for the consecu- tive periods are remarkably constant. The highest is that for the first period, 203 c.c., drawn from 10 periods; the lowest is that for the fifth period, 195 c.c., drawn from 21 periods. Although the average value for the fifth period is lower than that for the first, we do not find here, as with some of the experiments made with the 8-hour method, any tendency towards a falling off or material alteration of the values as the day progresses. The greatest mean variation, 11.3 c.c., occurs in the first period, this being slightly more than 5 per cent of the average value for this period. The mean variation of the averages for all the periods is but 7.8 c.c., an agreement that indicates uniform experimental conditions and ac- curacy in technique. From the general picture of the carbon-dioxide production of this subject during the period of five years, which is obtained from the averages in the extreme right-hand column, we find that while there are individual variations there is no general tendency toward a material alteration in the metabolism; this is further confirmed by the small average mean variation. We may therefore infer that the carbon- dioxide production of this subject did not vary to any extent in the course of the five years of experimenting. The average carbon-dioxide production for H. L. H., as shown by the determinations made during this period, may be considered as 198 c.c. per minute. BASAL METABOLISM. 101 TABLE 37. — Carbon-dioxide produced at different times of day in respiration experiments; subject H. L. H., in post-absorptive condition and lying on couch. (Values per minute.) Average age, 25 years. Average body-weight (naked), 61.4 kilograms. Height, 172 cm. Date. Duration of First half Second half Third half Fourth half Fifth half Sixth half Seventh half Eighth half Aver- experiment. hour.1 hour.1 hour.1 hour.1 hour.1 hour.1 hour.1 hour.1 ape. 1910 c.c. c.c. c.c. c.c. c.c. c.c. c.c. c.c. c.c. May 23 8h30ma.m. to Ilh05ma,m. . 206 201 202 206 199 203 May 28 8 28 a.m. to 11 54 a.m. . 198 194 190 205 206 206 195 199 June 1 8 35 a.m. to 12 01 p.m. . 191 193 205 185 192 199 209 196 June 4 8 24 a.m. to 11 07 a.m. . 193 203 193 192 193 202 196 June 9 8 30 a.m. to 11 57 a.m. . 189 204 181 190 197 190 184 191 June 22 8 41 a.m. to 11 41 a.m. . 190 180 181 189 197 193 188 July 16 8 45 a.m. to 11 19 a.m. . 195 182 205 196 199 195 July 25 8 46 a.m. to 11 13 a.m. . 188 197 182 202 194 208 195 1911. Mar. 25 8 30 a.m. to 9 40 a.m . . 201 200 204 202 May 17 8 31 a.m. to 9 51 a.m. . 188 189 195 191 May 24 8 40 a.m. to 10 39 a.m . . 178 185 185 185 183 June 1 8 43 a.m. to 9 38 a.m . . 197 197 197 June 7 8 51 a.m. to 9 39 a.m . . 190 192 191 July 1 8 58 a.m. to 10 19 a.m. . 185 194 198 192 Sept. 11 8 22 a.m. to 9 36 a.m . . 212 207 211 . . . 210 Sept. 20 8 49 a.m. to 10 10 a.rn . . 189 207 221 206 Sept. 21 8 48 a.m. to 10 06 a.m . . 210 204 210 208 Sept. 22 8 53 a.m. to 10 06 a.m . . 196 201 199 199 Sept. 23 8 53 a.m. to 10 11 a.m. . 196 195 195 . . . 195 Sept, 24 8 15 a.m. to 9 42 a.m . . 229 203 207 198 209 Oct. 2 8 51 a.m. to 10 05 a.m. . 185 196 204 195 Oct. 5 8 57 a.m. to 10 06 a.m. . 182 190 192 188 Oct. 6 8 49 a.m. to 10 00 a.m. . 193 201 206 . . . 200 Nov. 21 9 03 a.m. to 9 41 a.m . . 218 207 . . . 213 1912. Jan. 9 811 a.m. to 9 24 a.m. . 213 209 211 . . . 211 Jan. 10 7 50 a.m. to 8 54 a.m . . 214 217 215 . . t 215 Jan. 11 8 38 a.m. to 9 41 a.m. . 216 192 198 202 Jan. 12 8 02 a.m. to 9 01 a.m. . 205 207 215 . . . • • 209 Jan. 13 8 04 a.m. to 9 07 a.m . . 198 208 178 • 195 Nov. 4 8 25 a.m. to 9 43 a.m . . 23~1 223 234 229 Nov. 5 8 11 a.m. to 9 11 a.m. . 196 198 218 . . . 204 Nov. 6 8 14 a.m. to 9 10 a.m. . 190 196 203 198 Nov. 12 8 21 a.m. to 9 25 a.m . . 191 178 185 185 1913. May 14 9 06 a.m. to 11 23 a.m. . 196 197 191 215 210 202 1914. May 27 8 01 a.m. to 8 38 a.m. . 191 179 . . . 185 June 2 8 56 a.m. to 9 29 a.m . . 190 179 185 June 3 8 53 a.m. to 9 35 a.m . . 189 178 . . . 184 June 6 9 36 a.m. to 10 08 a.m 190 177 184 Nov. 5 8 57 a.m. to 9 31 a.m . . 203 203 ... 203 Nov. 28 8 53 a.m. to 9 30 a.m. . 211 203 . . , 207 1915. Jan. 20 8 57 a.m. to 10 01 a.m . . 189 195 196 193 Jan. 22 9 50 a.m. to 11 51 a.m 187 183 187 189 202 190 Feb. 11 9 09 a.m. to 10 29 a.m. . 198 194 192 193 194 June 1 7 56 a.m. to 8 43 a.m . . 183 198 180 • > • t 187 June 2 7 49 a.m. to 8 37 a.m. . 210 199 196 202 Davs 10 23 42 36 21 11 10 5 245 Minimum . ... 183 179 178 178 177 185 189 184 183 Maximum 229 231 223 234 221 215 210 209 229 Average 203 201 197 196 195 196 200 197 198 M. V . 11.3 9. 1 9.5 8.0 8.0 7.2 5.3 7.2 7.8 'The experimental periods were usually 15 minutes in length and there was but one period in each half hour. 'The total number of periods in which the carbon-dioxide was determined in the 45 experiments was 158. 102 FOOD INGESTION AND ENERGY TRANSFORMATIONS. TABLE 38. — Oxygen consumed at different times of day in respiration experiments; subject, H. L. H.t in post-absorptive condition and lying on couch. (Values per minute.) Average age, 25 years. Average body-weight (naked), 61.4 kilograms. Height, 172 cm. Date. Duration of experiments. First half hour.1 Second half hour.1 Third half hour.1 Fourth half hour.1 Fifth half hour.1 Sixth half hour.1 Seventh half hour.1 Eighth half hour.1 Aver- age. 1910. Mav 23 ghgQma m to 1 l^OS^a m c.c. c.c. 234 c.c. 236 c.c. 223 c.c. c.c. 220 c.c. 229 c.c. c.c. 228 May 28 8 28 am to 11 54 a.m .... 227 239 231 236 242 253 244 239 8 35 a m to 12 01 p.m .... 228 246 237 236 233 243 251 239 8 24 am to 11 07 a.m . . . 226 233 229 236 236 248 235 June 9 8 30 am to 11 57 a.m . 217 223 20G 222 235 210 225 220 June 22 July 16 8 41 a.m. to 11 41 a.m. . . . 8 45 a.m. to 11 19 a.m .... 241 225 242 236 261 232 256 237 237 266 255 237 253 July 25 8 46 a.m. to 11 13 a.m. . . . 238 221 236 227 252 243 236 1911. Mar. 25 8 30 a.m. to 9 40 a.m .... 242 243 248 244 May 17 8 31 a.m. to 9 51 a.m. . . 236 227 234 232 May 24 8 40 a.m. to 10 39 a.m. . 229 218 225 224 June 1 June 7 July 1 Sept. 11 8 43 a.m. to 9 38 a.m .... 8 51 a.m. to 9 39 a.m 8 58 a.m. to 10 19 a.m .... 8 22 a.m. to 9 36 a.m . 246 240 232 224 231 233 231 234 246 233 237 232 230 241 Sept. 20 Sept. 21 Sept. 22 Sept. 23 Sept. 24 Oct. 2 Oct. 4 Oct. 5 Oct. 6 Nov. 21 1912. Jan. 9 Jan. 10 Jan. 11 8 49 a.m. to 10 10 a.m 8 48 a.m. to 10 06 a.m 8 53 a.m. to 10 06 a.m .... 8 53 a.m. to 10 11 a.m. . . . 8 15 a.m. to 9 42 a.m. . . . 8 51 a.m. to 10 05 a.m. . . . 8 53 a.m. to 10 09 a.m .... 8 57 a.m. to 10 06 a.m .... 8 49 a.m. to 10 00 a.m 9 03 a.m. to 9 41 a.m. . . . 8 11 a.m. to 9 24 a.m. . . . 7 50 a.m. to 8 54 a.m .... 8 38 a.m. to 9 41 a.m. . 281 249 245 274 254 245 245 270 282 260 272 270 225 248 237 249 237 248 242 229 263 274 259 259 266 230 249 242 256 243 235 263 277 265 266 241 246 246 257 265 278 261 266 273 232 248 242 254 240 250 244 236 Jan. 12 Jan. 13 Nov. 4 8 02 a.m. to 9 01 a.m .... 8 04 a.m. to 9 07 a.m. . . . 8 25 a.m. to 9 43 a.m . . 239 239 232 256 255 239 235 244 261 237 243 253 Nov. 5 Nov. 6 Nov. 12 8 11 a.m. to 9 11 a.m. . . . 8 14 a.m. to 9 10 a.m. . . . 8 21 a.m. to 9 25 a.m. . . 239 242 237 241 248 243 241 244 241 243 242 1913. May 14 1914. May 27 9 06 a.m. to 11 23 a.m. . . . 8 01 a.m. to 8 38 a.m . . 253 237 235 231 227 237 242 234 245 June 2 June 3 June 6 8 56 a.m. to 9 29 a.m .... 8 53 a.m. to 9 35 a.m .... 9 36 a.m. to 10 08 a.m . . 237 221 224 226 238 230 230 224 234 Nov. 5 Nov. 28 1915. Jan. 20 Jan. 22 8 57 a.m. to 9 31 a.m. . . . s ."i3 a.m. to 9 30 a.m .... 8 57 a.m. to 10 01 a.m. . . . 9 50 a.m. to 11 51 a.m. . 239 237 237 237 234 235 231 235 226 226 228 238 238 236 236 230 Feb. 11 June 1 June 2 9 09 a.m. to 10 29 a.m 7 56 a.m. to 8 43 a.m 7 49 a.m. to 8 37 a.m 223 249 242 243 240 220 244 236 242 245 241 228 245 Days 10 oo 49 Q7 99 10 5 -40 Minimum 2r>rl 217 920 9nfi ^18 290 210 225 220 Maximum °81 274 9U9 074 977 252 266 255 278 Average 246 241 940 240 949 935 240 243 241 M. V q 7 8 6 n t 11 '' 13 0 6 8 111 8 8 9 0 experimental periods were usually 15 minutes in length and there was but one period in each half hour, total number of periods in which the oxygen was determined in the 46 experiments was 159. BASAL METABOLISM. 103 Our study of the results of this series has thus far been based solely upon the data obtained regarding the carbon-dioxide production, but a more logical basis of discussion for changes in metabolism is to be found in the values for the oxygen consumption. These are recorded in table 38. Certain data obtained under special abnormal conditions, as an experimentally induced acidosis, are of course excluded, and so far as we are aware the figures given may properly be used for basal values. The averages at the bottom of the table show that the oxygen consumption per period as the day advanced remained noticeably constant. The highest average (246 c.c.) is that for the first period; the lowest average (235 c.c.) is found for the sixth period. Inasmuch as the average values for the seventh and eighth periods are materially higher than the average found for the sixth period, it is reasonable to consider that the oxygen consumption of H. L. H. shows no general trend toward a decrease in the metabolism, as the measurements con- tinued from 8 a. m. to midday. This conclusion is further justified by the fact that the mean variation from the general average is only 9 c.c. The mean variations for the individual periods, as shown in the last line of the table, agree satisfactorily and give evidence of uniformity in the experimental conditions and accuracy of the experi- mental work. The average oxygen consumption of this man over a period of five years, as shown by the general average, is 241 c.c. The averages in the extreme right-hand column indicate that the oxygen consumption, like the carbon-dioxide production, had no general tendency to alter in value as time progressed, with the single exception of a group of five experiments from September 20 to 24, 1911, inclusive. On those days the values approached very closely to an average of 270 c.c. During these five days the subject, although in a post-absorptive condition during the observations, was living on a diet containing a liberal amount of protein and fat but only 125 grams of carbohydrate.1 This diet was sufficiently low in carbohydrates to alter the metabolism of the subject materially. We do not feel justified, however, in omitting the results from the table. It may be stated, therefore, that with the subject H. L. H. the a verage values for both the carbon-dioxide production and oxygen con- sumption were notably constant, both from period to period and during a period of five years, but that the individual values varied considerably at times. EXPERIMENTS WITH L. E. E. Another series of experiments was carried out with Mr. L.E. Emmes, who has also long been associated with this laboratory. This series extended from April 26, 1909, to July 29, 1915, inclusive, all but one Benedict and Higgins, Am. Journ. Physiol., 1912, 30, p. 217. 104 FOOD INGESTION AND ENERGY TRANSFORMATIONS. of the experiments being made prior to June 6, 1911. Data for 8 half-hour periods, secured approximately between 8 a. m. and Ilh30m a. m., are available for comparison purposes. Considering first the table showing the carbon-dioxide production (table 39), it is found that with this subject the average value for the first period is extraordinarily high (224 c.c.), while the subsequent TABLE 39. — Carbon dioxide produced at different times of day in respiration experiments; subject L. E. E., in post-absorptive condition and lying on couch. (Values per minute.) Average age, 31 years. Average body-weight (naked), 59.8 kilograms. Height, 176 cm. Date. Duration of experiments. First half hour.1 Seconc half hour.1 Third half hour.1 Fourth half hour.1 Fifth half hour.1 Sixth half hour.1 Seventh half hour.1 Eighth half hour.1 Aver- age. 1909. c.c. c.c. c.c. c.c. c.c. c.c. c.c. c.c. c.c. Apr. 26 8h09ma.m. to 9b37ma.m . . 225 200 212 210 212 Apr. 28 8 10 a.m. to 9 15 a.m. . 222 203 211 . . . . . . 212 Apr. 30 8 03 a.m. to 9 08 a.m . . 211 193 203 . . . . . . 202 May 3 8 03 a.m. to 9 15 a.m. . 252 217 231 . . . . . . 233 May 7 8 06 a.m. to 9 12 a.m . . 246 218 217 . . . 227 May 10 8 32 a.m. to 11 02 a.m. . 196 191 191 204 196 May 13 8 12 a.m. to 10 47 a.m . . 200 207 209 206 209 210 207 May 20 8 20 a.m. to 10 44 a.m . . 234 228 224 216 233 233 228 May 22 8 40 a.m. to 11 16 a.m. . . . . 2.30 221 228 238 249 248 236 June 1 8 43 a.m. to 10 56 a.m 215 208 218 204 212 230 215 June 9 8 58 a.m. to 11 13 a.m. . 219 201 210 228 219 .. '. 215 June 16 8 29 a.m. to 10 46 a.m 204 198 211 218 217 210 1910. Feb. 4 8 32 a.m. to 11 42 a.m 205 204 203 187 211 201 197 201 Feb. 8 8 38 a.m. to 11 30 a.m. . 197 195 197 199 187 197 195 Mar. 7 8 47 a.m. to 11 52 a.m. . 206 194 199 189 205 190 197 Mar. 19 8 44 a.m. to 11 45 a.m. . 206 192 199 208 197 209 207 203 Mar. 29 8 29 a.m. to 11 40 a.m. . 216 178 197 178 19.3 178 205 192 June 7 8 32 a.m. to 11 45 a.m. . 199 199 182 194 198 194 June 11 8 44 a.m. to 11 27 a.m. . . . . 202 195 199 195 208 198 200 July 1 8 47 a.m. to 10 56 a.m. . 193 193 199 196 195 July 6 8 36 a.m. to 11 10 a.m. . 202 194 215 194 222 205 205 July 14 8 40 a.m. to 11 20 a.m. . 188 191 191 186 191 201 191 Nov. 26 8 25 a.m. to 10 20 a.m . . 220 220 222 225 222 Nov. 29 9 15 a.m. to 10 59 a.m 200 207 211 205 206 Dec. 3 8 24 a.m. to 9 39 a.m . . 196 194 201 197 Dec. 9 7 59 a.m. to 8 44 a.m 205 192 199 1911. Mar. 23 8 42 a.m. to 9 46 a.m . . 202 202 209 204 May 15 8 44 a.m. to 9 53 a.m 189 189 188 189 May 22 8 37 a.m. to 9 44 a.m . . 184 198 187 190 May 29 8 30 a.m. to 10 24 a.m. . 185 182 178 187 183 June 5 8 48 a.m. to 10 02 a.m . . 187 ISO 201 189 1915. July 29 8 30 a.m. to 12 55 p. in . . 194 183 189 Days 8 24 30 26 20 18 12 7 Z32 Minimum 200 184 178 178 178 186 178 190 183 Maximum 252 2.30 231 228 238 249 248 207 236 Average 224 1?04 202 200 204 208 208 199 204 M. V 14.9 9.9 10.8 10.3 11.8 13.9 12.3 4.1 10.8 'The experimental periods were usually 15 minutes in length and in most instances there was but, one period in the half hour. aThe total number of periods in which the carbon -dixoide was determined in the 32 experiments was 148. BASAL METABOLISM. 105 values all lie very close to 200 c.c. If we exclude the first period, we find no evidence of change in the value as the day progresses. A closer examination of the figures shows that the high value on the first day is determined, in part at least, by values on May 3 and 7, on which the carbon dioxide excreted was 252 c.c. and 246 c.c., respectively, both values being considerably higher than those found on the subsequent TABLE 40. — Oxygen consumed at different times of day in respiration experiments; subject L. E. E., in post-absorptive cotidition and lying on couch. (Values per minute.) Average age, 31 years. Average body-weight (naked), 59.8 kilograms. Height, 176 cm. Date. Duration of First half Second half Third half Fourth half Fifth half Sixth half Seventh half Eighth half Aver- experiments. hour.1 hour.1 hour.1 hour.1 hour.1 hour.1 hour.1 hour.1 age. 1909. c.c. c.c. c.c. c.c. c.c. c.c. c.c. c.c. c.c. Apr. 26 8h09ma.m. to 9h37ma.m . . 242 243 244 239 242 Apr. 28 8 10 a.m. to 9 15 a.m. . 236 233 236 235 Apr. 30 8 03 a.m. to 9 08 a.m . . 234 239 248 240 May 3 8 03 a.m. to 9 15 a.m. . 229 236 232 . . . 232 May 7 8 06 a.m. to 9 12 a.m. . 243 232 232 236 May 10 8 32 a.m. to 11 02 a.m. . 242 235 231 243 238 May 13 8 12 a.m. to 10 47 a.m . . 238 246 239 252 235 232 240 May 20 8 20 a.m. to 10 44 a.m . . 241 257 256 249 252 244 250 May 22 8 40 a.m. to 11 16 a.m. . 240 252 249 253 263 253 252 June 1 8 43 a.m. to 10 56 a.m . . 268 248 277 252 273 271 265 June 9 8 58 a.m. to 11 13 a.m. . 248 247 258 260 274 257 June 16 8 29 a.m. to 10 46 a.m . . 263 280 264 257 264 266 1910. Feb. 4 8 32 a.m. to 11 42 a.m. . 232 239 248 238 259 273 248 Feb. 8 8 38 a.m. to 11 30 a.m... 253 235 247 249 247 243 246 Mar. 7 8 47 a.m. to 11 52 a.m. . 238 238 245 270 248 Mar. 19 8 44 a.m. to 1 1 45 a.m . . 248 236 244 253 252 236 245 Mar. 29 8 29 a.m. to 11 40 a.m. . 249 235 244 237 238 254 243 June 7 8 32 a.m. to 11 45 a.m. . 244 235 225 230 241 249 237 June 1 1 8 44 a.m. to 11 27 a.m 234 238 233 241 244 238 July 1 8 47 a.m. to 10 56 a.m . . 248 233 242 240 241 July 6 8 36 a.m. to 11 10 a.m 232 231 234 237 259 262 243 July 14 8 40 a.m. to 11 20 a.m. . 233 231 232 232 235 244 235 Nov. 26 8 25 a.m. to 10 20 a.m 257 248 256 263 256 Nov. 29 9 15 a.m. to 10 59 a.m . . 271 261 272 274 270 Dec. 3 8 24 a.m. to 9 39 a.m. . 237 233 237 236 Dec. 9 7 59 a.m. to 8 44 a.m . . 251 250 251 1911. Mar. 23 8 42 a.m. to 9 46 a.m . . 235 234 240 236 May 15 8 44 a.m. to 9 53 a.m . . 251 241 238 243 Mav 22 8 37 a.m. to 9 44 a.m . . 254 242 248 248 May 29 8 33 a.m. to 10 24 a.m . . 225 235 243 242 236 June 5 8 48 a.m. to 10 02 a.m . . 237 223 226 229 1915. July 29 8 30 a.m. to 12 55 p.m. . 229 224 227 Days 8 24 29 26 20 16 12 5 232 Minimum 229 225 224 223 226 230 235 244 227 Maximum 251 268 280 277 263 273 274 273 270 Average 239 244 241 244 245 249 255 253 244 M. V 5.0 9.5 7.5 9.5 9.5 12.6 13.4 8.6 8.1 'The experimental periods were usually 15 minutes in length and in most instances there was but on enod in the half hour. 2The total number of periods in which the oxygen was determined in the 32 experiments was 143. 106 FOOD JNGESTION AND ENERGY TRANSFORMATIONS. periods of the same day. The average carbon-dioxide production of this subject over a period of approximately six years was 204 c.c. An examination of the figures in the extreme right-hand column shows a tendency for the carbon-dioxide production to be lower during the last half of the series than during the first half. When the values for the oxygen consumption given in table 40 are examined, it is seen that the discrepancy in the carbon-dioxide pro- duction which was noted for the first period does not appear in the oxygen values. Indeed, there is a possible tendency for the oxygen consumption to increase slightly as the day goes on. The average value for the first half-hour drawn from 8 periods is 239 c.c. ; those for the fifth to the eighth periods are all 245 c.c. or over, with the last three per- ceptibly higher. On the other hand, the average value for the whole series of observations is 244 c.c., which does not indicate a trend toward variation in oxygen consumption as the day progresses. As was the case with H. L. H., variations from period to period on the same day are frequently noted. The mean variation, like that for the carbon-dioxide production, is small, which is indicative of a satisfactory technique. The values in the extreme right-hand column show that in a period of six years there was no apparent tendency for the oxygen to alter its value to any great extent, but as the last three values are measurably lower than the average, it may be necessary to limit the period of approximately constant metabolism to the time between April 26, 1909, and May 22, 1911, especially as but one value was obtained after June 5, 191 1. The data in table 40 give no conclusive evidence, however, that a period of six years is sufficient to alter materially the average metabolism of this subject. EXPERIMENTS WITH J. K. M. The third subject was a former laboratory assistant, J. K. M. Values for eight periods, i. e., from approximately 8h30m a. m. to 12h 30m p. m., are recorded. The data for the carbon-dioxide production are given in table 41 ; the general average for the entire series of obser- vations, which is shown in the last line of the table, is 183 c.c. There is no indication of a material change in the metabolism during the forenoon, although wide variations occasionally appear from period to period. The average values for each experiment, which are given in the right-hand column, show that during the period from May 24, 1912, to July 23, 1913, or one year and two months, there was no general tendency for the carbon-dioxide production either to increase or to decrease, as the values for the most part lie quite close to the gen- eral average. The chief exceptions are the minimum value of 165 c.c. on June 29, 1912, and the maximum value of 210 c.c. on May 24, 1912. This latter value was obtained on the first day of experimentation, when, owing to the novelty of the situation, the metabolism is usually higher than on subsequent days. BASAL METABOLISM. 107 As with the other subjects, the values for the oxygen consumption are more regular than those for the carbon-dioxide production. (See table 42.) The average for the values obtained in each period, as given at the end of the table, show a striking constancy in the metabolism throughout the day, the lowest average being 221 c.c. and the highest 227 c.c. On the other hand, the actual minimum and maximum values obtained in the individual periods show a wide variation. In the TABLE 41. — Carbon dioxide produced at different times of day in respiration experiments; subject J. K. M., in post-absorptive condition and lying on couch. (Values per minute.) Average age, 23 years. Average body-weight (naked), 60.4 kilograms. Height, 173 cm. Date. Duration of experiments. First half hour.1 Second half hour.1 Third half hour.1 Fourth half hour.1 Fifth half hour.1 Sixth half hour.1 Seventh half hour.1 Eighth half hour.1 Aver- age. 1912. c.c. c.c. c.c. c.c. c.c. c.c. c.c. c.c. c.c. May 24 8h45ma.m. to 9h58ma.m. 204 201 224 210 May 28 10 00 a.m. to 11 45 a.m. 192 187 202 184 . . . 191 June 4 8 49 a.m. to 10 30 a.m. 193 194 200 192 195 June 11 8 48 a.m. to 11 48 a.m. 178 179 182 172 194 . . « 181 June 13 8 39 a.m. to 11 25 a.m. 183 178 177 185 172 185 180 June 18 8 56 a.m. to 11 41 a.m. 177 178 175 173 169 189 177 June 20 8 30 a.m. to 11 41 a.m. 175 166 177 186 179 195 181 180 June 26 8 51 a.m. to 11 32 a.m. 178 172 165 181 162 174 169 . . . 172 June 29 8 47 a.m. to 11 21 a.m. 164 16.3 176 163 152 173 164 . . . 165 July 1 8 59 a.m. to 11 44 a.m. 176 175 159 178 169 171 July 3 9 02 a.m. to 11 49 a.m. 169 167 170 181 196 159 174 July 9 9 07 a.m. to 12 01 p.m. 181 184 174 185 197 184 July 12 8 58 a.m. to 11 45 a.m. 174 164 176 182 176 179 170 174 July 31 10 42 a.m. to 11 58 a.m. 177 173 189 180 Sept. 20 8 43 a.m. to 11 29 a.m. 175 175 197 198 178 190 186 Sept. 21 8 45 a.m. to 11 36 a.m. 177 185 176 174 179 174 184 178 Oct. 29 9 30 a.m. to 11 55 a.m. 198 182 181 194 191 . . . 189 Oct. 30 8 57 a.m. to 12 15 p.m. 185 204 198 172 177 . . . 183 187 Oct. 31 9 04 a.m. to 12 05 p.m. 198 184 176 191 202 201 192 Nov. 19 8 55 a.m. to 10 54 a.m. 190 202 191 199 186 194 Nov. 26 9 53 a.m. to 10 49 a.m. 175 178 188 180 Dec. 3 8 50 a.m. to 11 29 a.m. 180 186 181 182 Dec. 12 9 35 a.m. to 11 00 a.m. 181 197 170 188 184 Dec. 14 10 16 a.m. to 10 57 a.m. 203 176 204 194 Dec. 15 10 07 a.m. to 10 35 a.m. . . . 182 181 182 1913. Jan. 23 8 58 a.m. to 11 52 a.m. 188 191 192 175 186 190 187 Mar. 14 8 51 a.m. to 11 27 a.m. 176 182 185 183 179 181 Apr. 29 9 38 a.m. to 11 47 a.m. 180 174 171 182 177 May 7 9 11 a.m. to 11 34 a.m. 180 164 181 173 185 174 176 June 5 9 11 a.m. to 12 30 p.m. 189 178 171 173 200 182 July 15 9 07 a.m. to 12 11 p.m. 195 178 179 175 191 184 July 18 9 12 a.m. to 12 58 p.m. 185 180 172 181 178 179 July 23 9 37 a.m. to 12 00 p.m. 178 173 194 199 186 Days 5 23 25 28 28 28 21 7 233 Minimum 164 163 164 163 152 169 159 170 165 Maximum 183 204 204 224 199 204 201 200 210 Average 175 181 181 185 178 183 182 187 183 M. V 4.8 8.1 8.7 9.8 7.7 8.0 9.1 8.7 6.3 experimental periods were usually 15 minutes in length and in all but one instance there was but one period in the half hour. 2The total number of periods in which the carbon dioxide was determined in the 33 experiments was 166. 108 FOOD INGESTION AND ENERGY TRANSFORMATIONS. average values for the experimental days a group may be observed from June 20 to July 3, 1912, with an average of 217 c.c., and on June 5 and July 18, 1913, averages of 212 c.c. and 211 c.c. respectively were obtained. Aside from these low values no tendency is shown toward an alteration of the metabolism throughout the period of experimenta- tion and we may fairly state that the average oxygen consumption of this subject as measured during a period of one year and two months is 225 c.c. TABLE 42. — Oxygen consumed at different times of day in respiration experiments; subject J. K. M., in post-absorptive condition and lying on couch. (Values per minute.) Average age, 23 years. Average body-weight (naked), 60.4 kilograms. Height, 173 cm. Date. Duration of experiments. First half hour.1 Second half hour.1 Third half hour.1 Fourth half hour.1 Fifth half hour.1 Sixth half hour.1 Seventh half hour.1 Eighth half hour.1 Aver- age. 1912. c.c. c.c. c.c. c.c. c.c. c.c. c.c. c.c. c.c. May 24 8h45ma.m. to 9h58ma.m. 234 237 234 . . i 235 May 28 10 00 a.m. to 11 45 a.m. 233 212 223 232 . . , 225 June 4 8 49 a.m. to 10 30 a.m. 224 229 221 224 . . * • 225 June 11 8 48 a.m. to 11 48 a.m. 238 230 • • • 225 227 233 231 June 13 8 39 a.m. to 11 25 a.m. 238 224 227 222 217 226 > • • 226 June 18 8 56 a.m. to 11 41 a.m. 241 236 233 238 231 247 • • • 238 June 20 8 30 a.m. to 11 41 a.m. 214 200 213 232 223 225 224 219 June 26 8 61 a.m. to 11 32 a.m. 222 215 217 219 216 207 223 217 June 29 8 47 a.m. to 11 21 a.m. 224 209 229 208 204 206 220 214 July 1 8 59 a.m. to 11 44 a.m. 217 212 205 211 227 . . , 214 July 3 9 02 a.m. to 11 49 a.m. 215 219 214 223 225 217 • . . 219 July 9 9 07 a.m. to 12 01 p.m. 236 242 227 227 233 235 . . . 233 July 12 8 58 a.m. to 11 45 a.m. • • • 213 219 221 213 214 215 219 216 July 31 10 42 a.m. to 11 58 a.m. 212 210 221 214 Sept. 20 8 43 a.m. to 11 29 a.m. < 220 234 242 250 235 233 236 Sept. 21 8 45 a.m. to 11 36 a.m. 231 244 233 235 230 233 240 235 Oct. 29 9 30 a.m. to 11 55 a.m. 236 223 227 231 236 231 Oct. 30 8 57 a.m. to 12 15 p.m. . . . 243 244 222 222 229 232 Oct. 31 9 04 a.m. to 12 05 p.m. 229 215 214 220 221 234 222 Nov. 19 8 55 a.m. to 10 54 a.m. 245 241 239 223 226 . . • 235 Nov. 26 9 53 a.m. to 10 49 a . m. 220 224 228 • • • 224 Dec. 3 8 50 a.m. to 11 29 a.m. 220 228 219 222 Dec. 12 9 35 a.m. to 11 00 a.m. 210 220 216 232 220 Dec. 14 10 16 a.m. to 10 57 a.m. 246 221 249 239 Dec. 15 10 07 a.m. to 10 35 a.m. 223 229 . . . . . . , . . 226 1913. Jan. 23 8 58 a.m. to 11 52 a.m. 232 231 227 220 229 239 230 Mar. 14 8 51 a.m. to 11 27 a.m. 228 224 230 233 223 • * • 228 Apr. 29 9 38 a.m. to 11 47 a.m. 229 235 226 223 228 May 7 9 11 a.m. to 11 34 a.m. 234 226 225 225 215 222 225 June 5 9 11 a.m. to 12 30 p.m. • • • 213 206 207 207 226 212 July 15 9 07 a.m. to 12 11 p.m. • . • 238 224 217 219 220 224 July 18 9 12 a.m. to 12 58 p.m. « . * • 217 216 209 209 202 211 July 23 9 37 a.m. to 12 00 m. 229 225 225 239 230 Days 5 23 25 28 28 28 21 7 133 Minimum 214 200 206 207 204 206 210 202 211 Maximum 238 245 244 246 250 249 247 239 239 Average 226 227 227 225 221 224 227 222 225 M. V 7.0 10.7 8.2 7.9 7.2 7.5 7.7 7.7 6.5 'The experimental periods were usually 15 minutes in length and in all but one instance there was but one period in the half hour. 2The total number of periods in whcih the oxygen was determined in the 33 experiments was 166. BASAL METABOLISM. 109 EXPERIMENTS WITH OTHER SUBJECTS. It is impracticable to publish in detail all of the values obtained with the other subjects included in this study, as the mass of data is so extensive. To show the particular point emphasized in this discussion of results, namely, the probable trend of the morning metabolism from 8 a. m. to 1 p. m., an abstract of the results for 29 subjects is presented in tables 43 to 45. These tables show the weight, height, and age of each subject, the limits of the period of time in which the experiments were made, the number of individual periods included in the experi- TABLE 43. — Gaseous metabolism at different times of day in respiration experiments; subjects in post-absorptive condition and lying on couch. (Values per minute.) Subject, naked weight,1 height, age.1 Time covered by experiments. Observation. <*• «H o <*M "3 £ £ h O ft V* "3 A •o a o o 1 | ••H 13 1 !S H | •— "3 J5 J3 +3 H O fa M O <— *3 ,-c •M £ b O i|H "c5 J3 A t< QQ Seventh half hour. Average of daily averages. DR. M. 75.9 kilos 29 periods, Apr. 30, 1913, (Avg. COS... •JAvg. O2 c.c. 202 256 c.c. 201 255 c.c. 204 257 C.C. 204 263 c.c. C.C. c. c. c.c. 200 254 175 cm 29 yr to Dec. 31, 1914. [Days. . 8 9 8 4 11 W. J. T. [29 periods Mar. 1 1913 Avg. CO2. . . Days 215 4 200 3 196 5 198 5 202 6 200 3 203 8 74.6 kilos 183 cm., 22 yr.. to May 3, 1913. Avg. Oj>. . . . ^Days 255 4 255 3 249 5 251 5 254 6 258 4 254 8 J. H. H. 69.3 kilos J24 periods, Dec. 20, 1912, f Avg. C02. . . •{Avg. O2. . . . 198 230 195 231 197 237 190 236 192 234 195 238 195 226 194 233 171 cm. 25 yr. to Apr. 18, 1913. Days 3 4 4 3 4 3 2 5 M. J. S. 161 periods July 19 1912 f Avg. C02. . . Davs 198 5 195 10 191 9 195 12 192 8 198 10 199 5 195 13 63.7 kilos. 170 cm., 24 yr. . to Aug. 6, 1912. ] Avg. O2 . . . . IDavs 237 4 233 10 231 9 239 12 234 8 241 10 242 5 235 13 R. G. [27 periods Dec. 22, 1912 [Avg. CO2... Davs 189 1 188 5 197 5 195 5 190 3 187 4 188 2 192 6 62.6 kilos. . 173 cm., 23 yr.. to Feb. 4, 1913. ] Avg. O2 [Days 233 1 230 5 231 5 231 5 223 3 223 5 229 2 228 6 J. E. F. '.21 periods Nov. 22, 1911 fAvg. CO2... j Davs. 210 4 207 5 208 5 204 2 204 1 197 2 185 2 206 6 60.5 kilos 172 cm., 21 yr.. to April 6, 1912. |Avg. O2 ! Days . . 255 4 236 5 233 4 233 2 223 1 239 2 233 2 237 6 H. B. L. 60.2 kilos }l4 periods, Feb. 20, 1912, ! Avg. CO2. . . 1 Avg. O2. . . . 201 239 192 226 178 216 186 222 191 227 185 225 187 224 173 cm., 20 yr. to April 5, 1912. i Davs 1 3 3 3 2 2 3 J. W. P. 1 18 periods, June 14, 1912, fAvg. CO2. . . J Days . . 201 3 202 3 213 2 203 2 197 3 196 2 202 2 201 3 56.7 kilos. . . . 172 cm., 30 yr.. to Oct. 22, 1912 i ]Avg. O2 1 Davs . 238 3 235 3 248 2 246 2 245 2 247 2 252 2 243 3 I. A. F. 55.6 kilos. . 1 11 periods, Mar. 26, 1912, [Avg. C02. . . \ Avg. Oo 176 220 186 221 187 221 182 217 185 219 186 224 184 221 156 cm., 24 yr. . to Apr. 4, 1912. [Davs 1 2 2 1 2 2 2 J. J. G. 50.3 kilos . ,29 periods, Mar. 17, 1913, fAvg. CO2... \ Avg. Os 174 194 184 201 174 205 177 210 171 202 165 196 175 206 174 204 164 cm., 21 yr. . to May 6, 1913. Days . . 1 3 7 4 6 3 4 9 1Average body-weight and average age for the series of experiments. 'The experimental periods were usually 15 minutes in length and in most instances there was but one period in the half hour. The average time of the first period used was at all times approximately between 8 a. m. and 0 a. m. 110 FOOD INGESTION AND ENERGY TRANSFORMATIONS. ments, and the average carbon-dioxide production and oxygen con- sumption in the successive half hours of the day; also the number of ex- perimental days from which each value is drawn. As in the preceding tables, grand averages are given for each subject for the carbon-dioxide production and oxygen consumption for the total number of experi- mental days, this being found by averaging the daily averages of each factor for all of the experiments with the individual subjects. The data are arranged according to the weight of the subjects in each group. As would be expected from the results found in tables 37 to 42, the data indicate that with these subjects, also, there is no noticeable tendency toward an alteration in the basal metabolism as the day progresses, particularly in the values for the oxygen consumption. TABLE 44. — Gaseous metabolism at different times of day in respiration experiments; subjects in post-absorptive condition and lying on couch. (Values per minute.) Subject, naked weight1, height, age.1 Time covered by experiments. Observa- tion. First half hour.2 H 13 O 43 '— "rt 43 •a 13 O c HI 03 h 3 0 M «4H "c3 43 -o IH 43 H i4 o 43 «*H "3 43 43 49 LH O fe u, o 43 V* "3 42 -4-i *«-( £ b O M **-i "3 43 X 02 Seventh half hour. b 0 •M "3 43 •5 -a w u 5 43 IM c« 43 43 d 2 IH a o 43 ••* *CJ 4= 43 42 a V H Average of daily averages. F. G. B. 83.6 kilos \38 periods, Mar. 1, 1909, (Avg. CO2. \ Avg. Oj . . c.c. 225 •>m C.C. 216 261 c.c. 213 ?54 c.c. 214 255 c.c. 225 251 c.c. 216 250 c. c. 215 ?49 c.c. 213 ?57 C.C. 209 ?59 c.c. 223 274 c.c. 214 flSS 183 cm., 40 yr. to Apr. 14, 1915. [Days ? fi 6 4 1 ?, 4 4 4 3 10 H. H. A. '.92 periods, Nov. 7, 1911, Avg. CO2. Days 1873 6 181 8 180 16 177 ?0 178 22 187 8 196 3 190 4 183 ?, 180 71 62.4 kilos 164 cm., 22 yr. 1 to Dec. 22, 1912. Avg. O2 . . Days 22bJ 6 214 7 214 15 212 20 213 22 216 8 2dO 3 223 4 217 ?, 214 ?,7 8. A. R. [si periods, Mar. 30, 1912, Avg. CO2. Days 178 1 170 3 172 4 172 5 174 3 166 2 177 4 177 4 191 ?, 179 3 172 8 60.8 kilos 166 cm., 23 yr. | to Aug. 14, 1912. Avg. O2. . Days fAvg. CO2. 212 1 188 203 3 202 200 4 ?05 204 5 210 195 3 207 200 2 212 207 5 ?10 212 3 215 210 2 208 3 208 8 ?09 J. B. T. 1 70 periods, May 27 1912 Days 4 10 10 12 10 10 8 3 12 60.0 kilos .... | to Jan 24 1913 lAve. Oi 246 252 251 249 249 257 249 247 ?5?, 171 cm., 20 yr. Days .... 4 10 q 12 10 11 7 3 12 W. F. B. fAvz CO» 184 207 200 197 195 197 190 181 198 59.9 kilos . 30 periods, Mar. 10, 1913, • Avc O? 219 235 231 229 227 220 244 241 230 168 cm., 32 yr. to July 22, 1913. Days 1 4 R 4 6 5 ?, ?, 7 D. J. M. Ul periods, Mar. 21, 1910, Avg. CO2. Davs. . 211 1 190 5 183 5 184 5 190 2 187 4 194 3 185 4 214 ?, 188 ft 68.0 kilos 176 cm., 20 yr. to May 20, 1910. Avg. O2. . Days 239 1 233 5 231 5 224 4 232 2 234 5 2Jb 3 232 4 240 ?, 232 6 A. G. E. fAvtr CO* 200 197 195 200 191 195 190 194 194 67.0 kilos 63 periods, Mar. 24, 1910, J Avff Oo 221 217 221 •7J7 215 212 219 220 217 169 cm., 25 yr. to Mar. 28, 1911. [Days 7 10 10 10 10 8 fi 2 13 P. F. J. A7 0 Irilnq ! 93 periods, Feb. 5, 1912, fAvg. CO2. (Days 196 1 196 15 191 13 191 15 190 10 184 10 187 9 189 8 191 3 193 3 192 18 167 cm., 20 yr. j to Nov. 14, 1912. ]Avg. O2.. [Days 234 1 230 15 232 13 230 15 227 10 226 10 234 10 243 8 247 3 249 3 233 18 'Average body-weight and average age for the series of experiments. The experimental periods were usually 15 minutes in length and in most instances there was but one period in the half hour. The average time of the first period used was at all times approximately between 8 a. m. and 9 a. m., except as otherwise noted. 'The average time of beginning the first period with this subject was 6h30m a. m. BASAL METABOLISM. Ill An examination of the detailed tables from which this abstract is made shows even more strikingly than with the subjects trained in the use of the apparatus, as were H. L. H., L. E. E., and J. K. M., that there were considerable variations in the individual values. While most of the material from which this abstract is drawn was more fragmentary than that given for the three subjects in detail, there is no evidence of a tendency for the metabolism to change in either direction during the period of experimentation. CONCLUSIONS REGARDING SHORT-PERIOD EXPERIMENTS. The results just discussed were obtained with men in good health, from 17 to 40 years of age. Unfortunately the observations of the metabolism of individuals over 30 years of age are not so extended as they should be; we are thus unable to state definitely that the lower- ing of the metabolism noted in practically all instances with people of advanced years had not already begun with the subjects about 40 years of age, but our evidence thus far obtained does not lead us to infer this. In any attempt to draw general conclusions from these short-period experiments we should depend more especially upon the values found for the oxygen consumption, as, being uninfluenced by the previous diet, they give a clearer picture of the actual metabolism. A general review of the results in tables 37 to 42 and of the results from which the average values in tables 43 to 45 are drawn shows that with all of the subjects the individual values fluctuated considerably at tunes, but that the average values from period to period indicate no general change one way or the other. The average values for the experiments during a period of several months or years show a general constancy in the metabolism, there being but few average values which vary widely from the general average for the whole period. This is emphasized by the fact that the general mean variations for the various subjects were not large. The general constancy in the metabolism during the dif- ferent hours of the day and during different months and years thus seems to be fairly well established by these data, at least for individuals between 17 and 40 years of age. The variations in the individual values make clear the fact that single determinations should not be relied upon and that in order to obtain a value for the basal metabolism it is necessary to secure two or three well-agreeing periods for averaging. Inasmuch as the average values from period to period did not tend to change in any one direction, they were evidently free from diurnal influence; this factor may there- fore be eliminated in considering the results of comparison experiments in which the metabolism during fast is first determined and subse- quently the metabolism after food. This leads us, therefore, to the general conclusion that the determination of basal values immediately prior to the ingestion of food is the most logical and satisfactory method for studying the small changes in the metabolism frequently noted after the ingestion of food. 112 FOOD INGESTION AND ENERGY TRANSFORMATIONS. TABLE 45. — Gaseous metabolism at different times of day in respiration experiments; Subject, naked weight,1 height, age.1 Time covered by experiments. Observa- tion. w. h O V* 'd M •w M hi s £ O «M •a — T3 a 8 09 CO M O V* 13 43 •o 43 H h 0 43 •— ~£ A u O '- i- 0 43 «*-, "3 -»-j «— £ * | — "3 43 +* M 02 — "3 43 h o § g-S o CO 1 T! 43 5 43 on H fAvg. CO2. c.c. 216 c.c. 208 c.c. 211 c.c. c.c. C.C. c.c. c.c. H. R. R. [11 periods, Apr. 22, 1915, | Avg. O2 . . 278 ?,7?, ?70 69.5 kilos, 185 cm., 19 yr. \ to April 23, 1915. Days. . 2 ? 2 A. J. O. 69.3 kilos, 180 cm., 30 yr . f 100 periods, Nov. 4, 1914. 1 to Feb. 8, 1915. (Avg.C02. Avg. O2 . . [Days fAvg.CO2. 1 Days . . 216 252 6 2033 1 214 250 22 189 1 208 247 20 185 3 207 247 13 197 T> 206 254 4 192 9^ 202 247 3 194 19 208 259 2 194 18 200 241 1 193 1? K. H. A. 66.4 kilos, 182 cm., 26 yr . J R [139 periods, July 27, 1911, | to June 26, 1912. /54 periods Feb. 25, 1909, Avg. O2. . (Days fAvg.C02. Davs . . 2523 1 23 13 1 228 1 211 1 241 2 213 4 241 12 202 7 242 23 199 10 238 18 200 7 236 18 204 6 238 12 200 6 66.0 kilos, 182 cm., 27 yr. J. J. C. 65.0 kilos, 175 cm., 26 yr . \ to June 2, 1909. /258 periods, Feb. 26, 1909, \ to Apr. 25, 1911. ]Avg. O2.. [Days [Avg. CO2. ! Days .... Avg. O2 . . Days. . 2523 1 194 2 241 2 244 1 193 12 229 11 237 4 191 37 231 S5 242 8 193 38 230 ?8 244 9 189 42 229 40 246 7 188 29 225 28 244 6 189 26 227 24 245 6 191 24 229 ?3 fAvg. CO2. 178 162 164 17'? H. "W . F. 58.0 kilos, 174 cm., 25 yr. [41 periods, Jan. 27, 1915, \ to July 30, 1915. JAvg. O2. . [Days 224 3 205 5 210 ?, 223 1 H. F. T. 57.8 kilos, 179 cm., 32 yr. ("272 periods, June 8, 1911, \ to Jan. 30, 1912. fAvg.CO2. 1 Days .... Avg. O2.. Davs 1684 6 2004 6 158 9 191 7 158 10 192 q 173 11 195 1 1 168 19 198 ^n 172 28 193 27 171 20 194 20 167 27 194 ?fi V. G. (63 periods, Nov. 4, 1910, (Avg.C02. Days . . 201 6 194 11 190 11 197 q 198 4 219 1 204 5 190 1 54.7 kilos, 162 cm., 17 yr . I to Mar. 11, 1911. Avg. O2 . . Days . . 240 6 229 11 228 11 229 q 236 4 233 1 231 6 230 1 T. H. H. [44 periods, Feb. 17, 1915, fAvg.CO2. \ Avg. O2 . . 176 205 179 ^05 182 ?07 175 199 167 iqq 54.5 kilos, 171 cm., 29 yr . \ to Mar. 31, 1915. 1 Days . . 3 10 10 4 i fAvg. CO2. 167 169 164 163 W. K. [39 periods, Feb. 20, 1915, \ Avg. O2 . . 196 °00 194 •?01 49.7 kilos, 162 cm., 29 yr . \ to July 16, 1915. Days . . 3 6 5 1 T. M. C. f 100 periods, Mar. 23, 1909, fAvg.C02. 1 Days . . 168 4 157 10 154 13 152 17 152 15 153 14 155 11 156 9 48.5 kilos, 165 cm., 32 yr . ( to May 27, 1914. Avg. O2. . [Days 183 4 188 9 184 14 183 14 180 14 183 14 187 10 188 9 'Average body-weight and average age for the series of experiments. 2The experimental periods were usually 15 minutes in length and in most instances there was but one period in the half hour. The average time of the first period used was at all times approximately between 8 a. m. and 9 a. in., except as otherwise noted. 3The average time of the first period with this subject was 7 a. m. 4The average time of the first period with this subject was 6h30ra a. m. BASAL METABOLISM. 113 subjects in post-absorptive condition and lying on couch. (Values per minute.) § 43 — "3 S3 a £ t-, 3 O 43 *— "3 43 -c •*£ a V H Eleventh hall hour. I 43 s 43 0 - 43 •— "o rfc Thirteenth hall hour. Fourteenth hal: hour. Fifteenth hall hour. Sixteenth hall hour. Seventeenth hal hour. Eighteenth hal hour. Nineteenth hal hour. Twentieth hal hour. 1 43 ** & & 5 *J a 1 Average of dailj averages. Subject, naked. weight,1 height, age.1 c.c. 218 C.C. 219 c.c. 209 C.C. c.c. c.c. c.c. c.c. c.c. c.c. c.c. c.c. c.c. c.c. 213] 9 BO 2Q9 285 280 • . R. R. 1 2 2 2 69.5 kilos, 185 cm., 19 yr. 199 205 212 203 205 2101 247 251 252 247 254 249 f A. J. O. 1 2 3 4 4 24j 69.3 kilos, 180 crn., 30 yr. 198 190 194 194 194 190 201 194) 11 13 10 4 4 2 2 28 1 K. H. A. 977 932 236 235 242 °36 240 239 [ 66.4 kilos, 182 cm., 26 vr. 13 10 4 4 2 2 28J 9Q7 199 188 2021 6 3 2 12l J. R. 245 253 240 243 f 66.0 kilos, 182 cm., 27 yr. g 3 2 12J 189 188 193 196 °08 206 204 191 1911 Ifi fi 3 3 2 1 2 4 3 52l J. J. C. 974 934 237 242 229 243 233 240 240 230 1 65.0 kilos, 175 cm., 26 yr. 15 7 3 2 2 1 2 4 3 52! 168 172 185 180 176 171 1721 9f)fi 211 231 224 217 213 214V H. \V. F. 2 2 1 3 4 4 9j 58.0 kilos, 174 cm., 25 yr. 161 16 189 16 198 165 20 194 19 196 156 15 185 15 195 163 16 187 16 191 153 11 179 11 199 159 9 186 9 157 10 185 10 159 10 190 10 149 3 181 3 155 4 190 4 156 3 189 3 158 3 189 3 167 3 188 3 165] 44 192 f 44j 1951 H. F. T. 57.8 kilos, 179 cm., 32 yr. 3 4 2 3 3 u\ V. G. 231 240 230 233 233 231 1 54.7 kilos, 162 cm., 17 yr. 3 1 3 3 14 188 185 183 186 1801 226 220 217 206 207^ . H. H. 2 K 4 f) 12 54.5 kilos, 171 cm., 29 yr. 151 159 166 169 178 170 175 165 1681 166 192 199 205 217 190 202 197 200 \ \\ . K. I o c u 3 1 1 2 c 8 49.7 kilos, 162 cm., 29 yr. 161 165 162 1541 3 2 2 isl T. M. C. 196 188 190 184 1 48.5 kilos, 165 cm., 32 yr. 4 9 9 18 114 FOOD INGESTION AND ENERGY TRANSFORMATIONS. USE OF AVERAGE BASAL VALUES FOR COMPARISON. A considerable amount of experimental evidence has accumulated regarding the relationship of the average basal values of different individuals.1 The comparison of the results obtained with different subjects has been much discussed, together with the varying effects upon them of the factors influencing the basal metabolism, such varia- tions depending upon the different conditions of nutriment and environ- ment. Here, however, we are particularly interested only in those factors which influence the basal metabolism of a single individual. The question arises : To what extent is it possible to determine the basal metabolism of a subject and assume that this value is constant and may be logically used as a general base-line for food experiments subse- quently carried out? When several basal experiments have been made with a subject, and a number of closely agreeing results have been obtained for that particular day, many investigators use this average basal value for comparison with results obtained on subsequent days without further comment. The short-period method admits of the duplication of experimental periods for comparison in securing an average basal value, but it is by no means certain that the general use of such a value is the wisest or the most satisfactory procedure. It is obvious that the metabolism will be somewhat affected by a material alteration in the body-weight, such as may take place in the course of a year or, with a growing individual, in a very much shorter space of time. A base-line determined under materially different weight conditions may not therefore be used for general comparison. Furthermore, seasonal variations may be possible. For example, we may ask whether a base-line determined in the winter may be logi- cally used for comparison in the summer. One of the most striking illustrations of seasonal variation was given in some observations made at the Massachusetts General Hospital upon Palmer.2 With essen- tially the same body-weight, the subject showed in summer a total heat production of 1,797 calories, 19.2 calories per kilogram of body-weight, and 707 calories per square meter of body-surface; in winter he had a total heat production of 2,004 calories, 21.4 calories per kilogram of body- weight, and 789 calories per square meter of body-surface. The question of possible seasonal variation has also been considered in connection with the results of our short-period experiments. To this end the values obtained for the consumption of oxygen per minute in the individual months have been averaged in table 46 for each subject who was studied during a period of at least 1\ months. The longest period of time during which experiments were made was that for 'Benedict, Emmes, Roth, and Smith, Journ. Biol. Chem., 1914, 18, p. 139; Benedict, ibid., 1915, 20, p. 263. 2Palmer, Means, and Gamble, Journ. Biol. Chem., 1914, 19, pp. 242 and 243. BASAL METABOLISM. 115 L. E. E. of 6j years. With none of the subjects were values obtained for every month in the year. The primary object in giving these average values is to note if there is a tendency for the metabolism to be distinctly higher at one season than another. TABLE 46. — Average oxygen consumption in different months of the year in respiration experi- ments without food.1 (Values per minute.) Month. < W W < W M ffl d &J d 1-9 ^ d a EH' H d -i fc h § P § M *s § •^ 9 EH fc w 9-! PQ •-» Jan. . c.c. 218 c.c. c.c. 259 C.C. 235 C.C. c.c. C.C. c.c. 239 C.C. c.c. c.c. 230 c.c. 244 c.c. 195 c.c. 252 Feb.. 217 230 231 188 247 241 244 239 Mar. 220 249 266 235 188 218 243 244 240 228 251 Apr. . 268 229 215 239 251 290 228 238 May. June. July 232 237 238 243 253 218 223 183 181 176 215 217 220 242 249 237 234 233 240 232 226 219 252 232 228 223 220 205 189 249 250 Aug. . 238 184 Sept. 241 2264 236 191 253 Oct. . 244 228 244 Nov . 200 250 229 191 263 242 237 250 230 245 Dec 212 240 230 244 259 227 237 281 lThia table includes all subjects on whom experiments were made during a period of at least 1\ months, the longest period being 6| years with subject L. E. E. 2See explanation of this high value on page 103. Examining the data for differences from month to month, we find that with H. H. A. the minimum of 200 c.c. occurs in November and that the maximum of 220 c.c. is found in March, with a difference of 10 per cent. In this particular case, therefore, the basal value deter- mined in November can not properly be used for studying small incre- ments measured in March. It does not follow, however, that we should invariably expect with H. H. A. a low metabolism in November with a higher metabolism in March. With the subject K. H. A. the variations are extremely small; the minimum value (230 c.c.) was found in February and the maximum (249 c.c.) in March. With F. G. B. a minimum of 243 c.c. was found in May and a maximum of 268 c.c. in April; with J. J. C. a minimum of 218 c.c. in May and a maximum of 235 c.c. in January and March; with T. M. C. a minimum of 176 c.c. in July and a maximum of 191 c.c. in November. The values for A. G. E. are practically constant for the 5 months during which he was measured. With L. E. E. a minimum of 237 c.c. was obtained in July and a maximum of 263 c.c. in Novem- ber; with H. L. H. a minimum of 233 c.c. in June and a maximum of 264 c.c. in September; with P. F. J. a minimum of 219 c.c. in July and a maximum of 251 c.c. in April; with Dr. M. a minimum of 232 c.c. in June and a maximum of 290 c.c. in April; with J. K. M. 116 FOOD INGESTION AND ENERGY TRANSFORMATIONS. a minimum of 220 c.c. in July and a maximum of 236 c.c. in Septem- ber; with M. A. M. a minimum of 237 c.c. in December and a maximum of 251 c.c. in March; with H. F. T. a minimum of 184 c.c. in August and a maximum of 205 c.c. in June; while with J. B. T. a minimum was found of 244 c.c. in October and a maximum of 281 c.c. in Decem- ber. It is thus clear that the metabolism of these subjects, as indicated by oxygen measurements alone, does not show regular seasonal vari- ations, but only noticeable differences in averages from month to month. Although in table 46 we have recorded only the oxygen measure- ments, yet it is evident that with these normal individuals the respira- tory quotient in the post-absorptive condition remains reasonably uniform at 0.85, so that for purposes of comparison we may assume that the oxygen consumption corresponds to the heat production. While, therefore, the data show somewhat large differences in the metabolism for the different months with different individuals, there is no uniform- ity other than the possible tendency for the high values to fall in the month of March, this occurring with four subjects, and for the minimum metabolism to fall in July, as also found with four subjects; but the results are not sufficiently uniform to draw definite conclusions as to the maximum and minimum metabolism occurring in these two months. The possible fluctuations in the metabolism have likewise been shown for 35 subjects1 who were studied for periods of time varying from 5 days to 4 years and 5 months. In all cases the subjects were in the post-absorptive condition and with complete muscular repose. The increase in the oxygen consumption is used as an index of the fluctua- tions of the metabolism, with the value for the minimum daily average as a basis. The figures indicate that the oxygen consumption varied above the minimum from 3.5 per cent to 31.3 per cent, with an average variation of 13.9 per cent. The greatest variations were found as a rule with those subjects studied for the longer periods. The results obtained with many of these subjects were considered in more detail in the preceding section. By reference to tables 37 to 45 it will be seen that while the average values showed usually no tendency to change materially during the months or years the subjects were studied, yet the values for the individual periods often fluctuated widely. With such fluctuations it would not be logical to use a basal metabolism determined on one day for comparison with the metabolism determined on another day, except possibly when the superimposed factor to be measured is of considerable size, as in severe muscular work. With well-trained subjects of long experience, an average basal value may be considered as more reliable than those obtained with untrained subjects. Perhaps one of the best illustrations of the constancy of metabolism with a thoroughly well trained subject is that of the pro- fessional bicycle rider, M. A. M., studied by Benedict and Cathcart,2 'Benedict, Journ. Biol. Them., 1915, 20, p. 263, table -1. 2Benedict and Cathcart, Carnegie Inst. Wash. Pub. No. 1*7, 1913. BASAL METABOLISM. 117 whose metabolism was determined practically every morning for several months. (See tables 47 and 48.) The uniformity of the average metabolism for the day throughout this extended period is striking, to say the least, the variations in the metabolism being small. In fact, these particular experiments have been cited as conclusive evi- dence that when the base-line has once been fairly established it may, with propriety, suffice as a common base-line for subsequent use. But in physiological experimenting of this kind a subject is rarely so com- pletely under control that he can be used daily for several weeks and even months in experiments with a respiration apparatus. Such condi- tions have never, we believe, been duplicated in experiments in which the influence of the ingestion of food had been primarily considered. In studying a superimposed factor with a great increase in metab- olism, such as that commonly occurring in severe muscular work experi- ments, the use of a common base-line is open to the least objection, but most factors have a less pronounced effect upon the metabolism than severe muscular work. Even with so constant a metabolism as that of M. A. M., it would be impossible to use an average basal value in many experiments with him on the influence of the ingestion of food, for the variations in the metabolism in the supposedly satisfactory collec- tion of basal values were at times plus or minus 5 or 10 per cent, and the total effect of many processes of digestion fall well within this limit. The constancy in the average metabolism shown in tables 37 to 45 confirm in practically every detail the general conclusions drawn by Gigon2 from the basal data obtained by him with the Sond£n-Tigerstedt TABLE 47. — Carbon dioxide produced at different times of day in, respiration experiments; subject M. A. M., in post-absorptive condition and lying on couch. (Values per minute.) Average age, 29 years. Average body-weight (naked), 66.0 kilograms. Height, 177 cm. Date. Duration of experiments. First half hour.1 Second half hour.1 Third half hour.1 Fourth half hour.1 Fifth half hour.1 Sixth half hour.1 Average. 1911. c.c. c.c. c.c. c.c. c.c. c.c. c.c. Deo. 7 9h04ma.m. to 10h41ma.m.. . 229 227 219 226 225 8 8 37 a.m. to 10 04 a.m.. . 203 203 202 211 205 11 10 11 am to 11 16 a m. 194 190 200 195 12 8 57 am to 10 02 a m. 202 197 195 198 13 8 33 a.m. to 9 37 a.m.. . 200 196 203 200 14 8 50 a.m. to 9 52 a.m. 217 214 216 216 15 8 29 a.m. to 9 31 a.m.. . 202 205 194 200 19 8 32 a.m. to 9 34 a.m.. . 204 200 196 200 20 8 25 a.m. to 9 19 a.m.. . 203 194 186 194 21 8 22 a.m. to 9 15 a.m. .. 202 199 196 199 22 8 27 a.m. to 9 22 a.m.. . 199 195 188 194 JThe experimental periods were usually 15 minutes in length and there was but one period in each half hour. 2Gigon, Munch, med. Wochenschr., 1911, 58, p. 1343. 118 FOOD INGESTION AND ENERGY TRANSFORMATIONS. TABLE 47 (continued). — Carbon dioxide produced at different times of day in respiration experi- ments; subject M. A. M., in post-absorptive condition and lying on couch. — (Values per minute.) Date. Duration of experiments. First half hour.1 Second half hour.1 Third half hour.1 Fourth half hour.1 Fifth half hour.1 Sixth half hour.1 Average. 1912. Jan. 1 2 9 33 a.m. to 8 35 a.m. .. 8 49 a.m. to 9 26 a m. c.c. 206 c.c. 208 198 c.c. 209 200 c.c. c.c. c.c. c.c. 208 1QQ 3 4 8 26 a.m. to 9 24 a.m.. . 8 26 a.m. to 8 41 a.m.. . 201 214 199 201 200 214 5 8 29 a.m. to 8 44 a.m. .. 213 213 8 8 34 a.m. to 9 10 a.m.. 205 204 205 9 8 30 a.m. to 9 10 a.m. .. 215 207 211 10 8 29 a.m. to 9 07 a.m. .. 206 211 209 12 8 34 a.m. to 9 10 a.m.. . 228 217 223 15 8 33 a.m. to 9 11 a.m. 235 229 232 16 8 36 a.m. to 9 14 a m. 212 210 211 17 8 30 a.m. to 9 10 a.m. .. 196 187 192 18 8 30 a.m. to 9 09 a.m. . 197 205 201 19 23 24 8 29 a.m. to 9 43 a.m.. . 8 42 a.m. to 9 47 a.m. .. 8 34 a.m. to 9 13 a.m.. . 196 211 210 200 211 192 201 209 199 210 201 25 26 8 36 a.m. to 9 40 a.m.. . 8 32 a.m. to 911am. 202 204 201 200 195 199 202 31 Feb. 1 2 6 7 8 9 13 14 15 16 20 21 23 26 27 29 Mar. 6 11 8 35 a.m. to 9 44 a.m. .. 8 46 a.m. to 9 26 a.m. .. 8 40 a.m. to 9 43 a.m. .. 8 47 a.m. to 11 50 a.m. . . 8 35 a.m. to 9 36 a.m. .. 8 36 a.m. to 9 31 a.m.. . 8 38 a.m. to 9 39 a.m.. . 8 38 a.m. to 9 43 a.m. .. 8 36 a.m. to 9 39 a.m.. . 8 38 a.m. to 9 36 a.m.. . 8 40 a.m. to 9 40 a.m.. . 8 46 a.m. to 9 49 a.m. .. 8 39 a.m. to 9 44 a.m. .. 9 05 a.m. to 9 43 a.m. .. 8 41 a.m. to 9 45 a . m. . . 8 40 a.m. to 9 42 a.m.. . 8 41 a.m. to 9 41 a.m. .. 8 47 a.m. to 10 01 a.m.. . 8 44 a.m. to 9 22 a.m. 227 214 206 208 196 204 206 191 199 189 195 203 218 202 221 212 202 208 190 206 191 192 194 187 191 209 188 209 195 202 229 235 218 218 216 195 211 189 208 183 193 207 187 188 203 191 200 200 208 217 229 212 221 225 213 ?208 222 214 204 2210 195 207 190 196 202 188 193 200 191 205 199 209 216 230 215 20 1245 p.m. to 202 p.m. 3200 22 26 8 22 a.m. to 10 35 a.m. . . 8 43 a.m. to 9 20 a . m. . 210 210 216 202 212 219 211 214 206 29 Apr. 16 1914. Apr. 18 8 43 a.m. to 9 50 a . m. . . 8 38 a.m. to 9 34 a.m.. . 8 24 a.m. to 10 03 a.m. . . 214 234 198 236 207 186 206 212 196 212 193 217 218 193 Days 43 50 39 10 4 2 454 Minimum 189 186 183 193 190 200 188 Maximum 235 236 229 225 226 208 232 Average 207 205 203 211 210 204 205 M. V 7.8 9.7 9.0 9.7 10.0 4.0 8.4 •The experimental periods were usually 15 minutes in length and there was but one period in each half hour. 2Two other results (seventh period, 207 c.c., and eighth period, 202 c.c.) were obtained and included in the average for the day. 'Average of results obtained in ninth to twelfth periods, 208, 190, 201, and 202 c.c., respectively. 'The total number of periods in which the carbon dioxide was determined in the 54 experi- ments was 154. BASAL METABOLISM. 119 apparatus in Stockholm and the Jaquet apparatus in Basel, and subse- quently by means of another apparatus employing a spirometer, Miiller valves, and mouthpiece, in the Poliklinik in Basel. Since the data obtained with the Stockholm apparatus were exclusively confined to carbon-dioxide production, they can not be taken as comparable values for indicating constancy in the total heat production. Never- theless it is important to note that, even on the basis of the figures presented by Gigon, variations of nearly 10 per cent are found, which far exceed in many instances the variations found in observations fol- lowing the ingestion of the several foodstuffs. Accordingly, in the final selection of a determined basal value, it is of fundamental importance that we should bear in mind the fact that in averaging a large number of experiments the tendency is for all of the irregularities to be eliminated. For a comparison with an average value obtained from a large number of food experiments it may be justifiable to use a basal value of this kind, but in a comparison with the results of only one or two food experiments the variations in the single periods must be taken into consideration. While in this research our experience in securing a general basal value for use is by no means satisfactory, it has occasionally been necessary to use an average base-line. Inasmuch as a large number of values were secured, it is probable that any variations in the individual values will be more or less eliminated in the grand average. Nevertheless it is quite clear that a general base-line, even for a well-trained subject who is experimented upon each day, can not properly be used for studying the minor factors influencing basal metabolism, such as may be found in connection with the ingestion of certain of the food materials studied. TABLE 48. — Oxygen consumed at different times of day in respiration experiments; subject M. A. M., in post-absorptive condition and lying on couch. (Values per minute.) Average age, 29 years. Average body-weight (naked), 66.0 kilograms. Height, 177 cm. Date. Duration of experiments. First half hour.1 Second half hour.1 Third half hour.1 Fourth half hour.1 Fifth half hour.1 Sixth half hour.1 Average. 1911. c.c. c.c. c.c. c.c. c.c. c.c. c.c. Dec. 7 9h04ma.m. to 10h41ma.m. . . 251 262 277 257 262 8 9 21 a.m. to 10 04 a.m.. . 246 247 247 11 10 11 a.m. to 11 16 a.m 232 243 238 238 12 9 22 a.m. to 10 02 a.m.. . 233 226 230 13 8 33 a.m. to 9 37 a.m. .. 226 222 231 226 14 8 50 a.m. to 9 62 a m 241 237 235 238 15 8 29 a.m. to 9 31 a.m.. . 254 252 245 250 19 8 32 a.m. to 9 34 a.m. .. 235 250 229 238 20 8 25 a.m. to 9 19 a.m. .. 226 227 225 226 21 8 22 a.m. to 9 15 a.m.. . 230 231 231 231 22 8 27 a.m. to 9 22 a.m.. . 229 217 229 225 experimental periods were usually 15 minutes in length and there was but one period in each half hour. 120 FOOD INGESTION AND ENERGY TRANSFORMATIONS. TABLE 48 (continued). — Oxygen consumed at different times of day in respiration experiments; subject M. A.M., in post-absorptive condition and lying on couch. (Values per minute.) Date. Duration of experiments. First half hour.1 Second half hour.1 Third half hour.1 Fourth half hour.1 Fifth half hour.1 Sixth half hour.1 Average. 1912. To»-l 1 8 33 a m to 9 35 a m c.c. 232 c.c. 233 c.c. 233 c.c. c.c. c.c. c.c. 233 JED. 1 o 8 49 am. to 9 26 a.m. 231 232 232 3 4 8 26 a.m. to 9 24 a.m. .. 8 26 a m to 8 41 a m. 233 235 237 229 233 235 K 8 29 a m to 8 44 a m. 233 233 8 9 8 34 a.m. to 9 10 a.m. .. 8 30 a m to 9 10 a m. 228 237 234 246 231 242 10 8 29 a m to 9 07 a m. 258 259 259 12 8 34 a m to 9 10 a m 266 259 263 15 8 33 a m. to 911am. 266 249 258 16 8 36 a m. to 9 14 a m. 250 245 248 17 18 8 30 a.m. to 9 10 a.m.. . 8 30 a m to 9 09 a m 253 255 249 267 251 261 19 23 24 8 29 a.m. to 9 43 a.m.. . 8 42 a.m. to 9 47 a.m.. . 8 34 a m to 9 13 a m 252 252 230 269 240 234 259 247 260 246 232 25 26 8 36 a.m. to 9 40 a.m.. . 8 32 a m. to 9 11 a m. 260 240 236 233 251 249 237 31 Feb. 1 2 6 8 35 a.m. to 9 44 a.m.. . 8 46 a.m. to 9 26 a.m.. . 8 40 a.m. to 9 43 a.m.. . 8 47 a m. to 11 50 a m. 235 243 241 239 247 243 244 242 247 233 225 234 2231 240 241 246 2233 7 8 9 13 14 15 16 20 21 23 26 27 29 Mar. 6 11 8 35 a.m. to 9 36 a.m. .. 8 36 a.m. to 9 31 a.m.. . 8 38 a.m. to 9 39 a.m.. . 8 38 a.m. to 9 43 a.m. .. 8 36 a.m. to 9 39 a.m.. . 8 38 a.m. to 9 36 a.m.. . 8 40 a.m. to 9 40 a . m. . . 8 46 a.m. to 9 49 a . m. . . 8 39 a.m. to 9 44 a.m.. . 8 42 a.m. to 9 43 a.m.. . 8 41 a.m. to 9 45 a.m.. . 8 40 a.m. to 9 42 a.m.. . 8 41 a.m. to 9 41 a.m.. . 8 47 a.m. to 10 01 a.m.. . 8 44 a.m. to 9 22 a.m. 236 260 244 234 239 234 220 243 243 229 229 242 253 232 254 237 235 232 228 223 250 232 234 245 241 257 261 245 231 254 246 230 233 240 222 250 233 243 243 235 265 257 248 258 233 256 242 233 235 234 222 248 236 236 239 239 258 259 247 20 12 45 p m to 2 02 p m »240 22 26 29 Apr. 16 19H. Apr. 18 8 22 a.m. to 10 35 a.m.. . 8 43 a.m. to 9 42 a.m.. . 8 43 a.m. to 9 50 a.m.. . 8 38 a.m. to 9 34 a.m.. . 8 24 a.m. to 10 03 a.m . . 255 232 277 249 226 245 235 283 238 229 254 232 269 250 229 249 282 232 248 250 233 278 246 229 Days 43 48 40 10 4 2 «54 Minimum 220 217 222 225 234 231 222 Maximum 277 283 269 282 257 238 278 Average 242 242 241 246 246 235 242 M. V. . . . 11 0 10.1 9.9 16.3 7.0 3.5 9.7 'The experimental periods were usually 15 minutes in length and there was but one period in each half hour. 'Two other results (seventh period, 231 c.c., and eighth period, 231 c.c.) were obtained and included in the average for the day. •Average of results obtained in ninth to twelfth periods, 246, 235, 236, and 241 c.c., respectively. 4The total number of periods in which the oxygen was determined in the 54 experiments was 153. GENERAL DETAILS. 121 GENERAL DETAILS REGARDING THE RESEARCH. The experiments in 1905, 1906, and 1907, included in this research on the effect upon the metabolism of the ingestion of food, were made at Wesleyan University, Middletown, Connecticut, and those subsequent to 1907 in the Nutrition Laboratory in Boston. Only the respiration calorimeter was used in the Middletown experiments. In the Boston experiments not only the chair and bed respiration calorimeters were employed, but also two forms of respiration apparatus — i. e,, the universal respiration apparatus and the Tissot respiration apparatus. With the calorimeters, the carbon-dioxide production, the oxygen consumption, and the heat production were determined; with the respiration apparatus, determinations were made only of the respir- atory exchange, the heat production being obtained by indirect calorimetrjr. The several apparatus have been fully described else- where ; brief descriptions are included in this publication.1 The general plan of experimenting has been given in the preceding section ; the rou- tine with the various apparatus has also been outlined with more or less detail in the discussion of the results of the experiments. In the Middletown calorimeter considerable freedom of movement was possible. In the 24-hour experiments with this apparatus the sub- ject was able to carry out the ordinary routine of a day, restricted only by the confines of the chamber and the experimental requirements for a minimum amount of activity. In the waking hours he sat in a chair; in the sleeping periods he lay on the bed. During the 8-hour experi- ments with the same apparatus he sat quietly in a chair. In the chair calorimeter in Boston the subject also sat in a chair for the entire experimental period and was instructed to reduce all movement to the minimum. In all these apparatus the water and urine vessels and telephone were placed conveniently near the subject, so that they could be used with the least activity possible. In the bed calorimeter the subject lay on an air mattress with few or no major changes of position. In the experiments with the two respiration apparatus the subject lay on a couch, practically without movement, during the periods. In the Middletown calorimeter experiments the individual periods were usually 2 hours in length; in the Boston calorimeter experiments they were shortened to 1 hour and in a few instances to 45 minutes. With the universal respiration apparatus the periods ordinarily approxi- mated 15 minutes in length; with the Tissot apparatus the periods were generally shorter. The observations in the experiments with the two 'For a description of the Middletown calorimeter, see Atwater and Benedict, Carnegie Inst. Wash. Pub. No. 42, 1905. For the chair and bed calorimeters, see Benedict and Carpenter, Carnegie Inst. Wash. Pub. No. 123, 1910. For the universal respiration apparatus, see Benedict, Deutsch. Arch. f. klin. Med., 1912, 107, p. 156; Carpenter, Carnegie Inst. Wash. Pub. No. 216, 1915. For the Tissot respiration apparatus, see Tissot, Journ. de physiol. et de path, gen., 1904. 6, p. 688, and Carpenter, Carnegie Inst. Wash. Pub. No. 216, 1915, p. 61. 122 FOOD INGESTION AND ENERGY TRANSFORMATIONS. respiration apparatus were not continuous, there being intermissions varying in length according to the conditions of experimenting, food material used, etc. It was usual to make a 15-minute observation every half hour during the experimental period, but the intermissions were often much longer. The intermissions with the Tissot apparatus were usually brief. As a rule, the subject lay on the couch during the intermissions with both apparatus and was more or less quiet. In the Middletown experiments the movements made by the subject were recorded by an observer, but in nearly all of the Boston experi- ments the degree of muscular repose was shown by some form of graphic record. In many of the calorimeter experiments observations were made of the body-temperature; the data recorded were secured per rectum, by means of an electrical-resistance thermometer. Records of the pulse rate were obtained with the Fitz pneumograph in the Middletown experiments, but in the calorimeter experiments in Boston and in the experiments with respiration apparatus the Bowles stethoscope was used, the counts being made by a special observer. Records of the respiration rate were secured in practically all of the Middletown and Boston calorimeter experiments and in the experi- ments with the tension-equalizer form of the universal respiration apparatus by means of the Fitz pneumograph. In the experiments with the respiration apparatus the pneumograph was connected with a kymograph, thus giving graphic records of the respiration. In the obser- vations with the spirometer form of the universal respiration apparatus, the graphic record of the respiration was provided by a mechanical de- vice attached to the spirometer instead of by the Fitz pneumograph. In several groups of the Boston experiments, i. e., those with water, coffee, and beef tea, records of the blood pressure were obtained with the Erlanger sphygmomanometer. Table 49 gives a list of the food experiments, grouped according to the apparatus and diet used. It shows that 59 experiments were made with the respiration calorimeter in Middletown, 41 experiments with the chair calorimeter and 3 experiments with the bed calorimeter in Boston. In the experiments in which only the respiratory exchange was determined, 78 experiments were made with the universal respira- tion apparatus and 9 experiments with the Tissot apparatus. The research included, in all, 190 experiments, i. e., 15 chewing experiments, 11 experiments with water, 8 with coffee, 13 with beef tea, 65 with carbohydrates, 15 with a fat diet, 44 with a protein diet, and 19 with mixed nutrients. The composition and fuel value of the food materials used in the experiments are shown in table 50. The values are, for the most part, directly determined or are computed from determined values. The composition of the mixed diets may be found in the section describing the experiments with mixed nutrients.1 'See table 235, p. 310. GENERAL DETAILS. 123 TABLE 49. — Summary of experiments folloiving the ingestion of food. Kind of experiment. Middletown calorimeter. Boston. Total Calorimeter. Universal respiration apparatus. Tissot respiration apparatus. Chair. Bed. Chewing 3 2 2 5 2 4 5 2 1 1 3 4 4 4 2 3 112 4 3 2 2 1 2 3 4 3 5 3 4 5 1 1 1 7 6 6 6 13 8 14 4 11 1 1 1 1 1 1 1 4 1 15 11 8 13 14 9 19 5 5 7 3 2 1 1 7 7 24 3 6 5 4 2 4 15 Water Coffee Beef tea Carbohydrates : Dextrose Levulose Sucrose Lactose Maltose-dextrose mixture. . . . Bananas and sugar Bananas Popcorn Rice (boiled) Fat: Mayonnaise Cream Butter and potato chips Protein: Beefsteak (cooked) Beefsteak and bread Beefsteak and potato chips . . Glidine Gluten and skim milk Plasmon and skim milk ... Mixed nutrients: Milk Mixed diet Total . . 59 41 3 78 9 190 include 6 heavy-breakfast and 2 heavy-supper experiments. Statistical data for the subjects of the experiments following the ingestion of food are given in table 51. In all there were 39 male subjects, the average age for the period of experimenting ranging from 17 to 48 years. The large majority of the subjects were from 20 to 30 years of age. The average body- weight without clothing ranged from 48 to 83 kilograms. The greater number of the subjects had a body-weight between 55 and 65 kilograms. The experiments with each class of nutrients are discussed in separate chapters in the following pages. In the tabulated results for the calorimeter experiments, the amount, nitrogen content, and total energy of the diet are given, also the fuel value, and the proportions of energy from the different nutrients. The basal values for the carbon- dioxide production, oxygen consumption, and heat production are likewise recorded, together with the basal nitrogen in the urine of the experimental day if this was obtained. Whenever the respiratory quo- tients are given for the food periods, the basal, respiratory quotient, 124 FOOD INGESTION AND ENERGY TRANSFORMATIONS. TABLE 50. — Percentage composition of food materials used in experiments.1 Food material. Pro- tein. Fat, Carbo- hydrates. Fuel value per gram. Remarks. Bananas p. ct. 1.32 p. ct. 0.62 p. ct. 22. 02 cals. 1.0142 Beefsteak (cooked) 22.9 5.43 1.4414 Analyzed for J. R., Dec. 4, 1908. Do 31.2 14. 54 2.630 Analyzed for A. W. W. May 25 1907. Do 28. 75 6 45 1.6794 Beef tea . . 1 36 0 I2 0 22 0 0724 Used for A. W W., May 2 1907 Do 2.57 O.I2 0.22 0.11S4 Bread, black 9.6 0.3 48. 92 2.4274 Bread, gluten8 89.4 0 3 4 8 4.195 Bread, white . ... 9 79 1 32 53 I2 2 6944 Butter l.O2 85. 02 8 . 0909 Coffee 0.5 2.7 0.1314 Analyzed for J. J. C., Mar. 9, 191 1.10 Do 0.29 1 O9 0.0504 Cream ... 2 7" 20 4* 4 52 2 18911 Used for H. R. D., Mar. 28, 1906. Do 2 4 29 8 4 52 3 0604 Analyzed for J. J. C., Mar. 22, 1910 Do 2.4 25.6 4.52 2 . 6644 Analyzed for D. J. M., June 3, 1910. Do 2 2 32 7 4 52 3.3124 Analyzed for D. J. M., June 7, 1910. Do 9 412 29 412 4 52 3 01 24 Used for D. J. M., Mar. 23, 1910. Dextrose13 100.0 3.739 Glidine 86.6 0.7 3.04 3.7394 Lactose13 100 0 3.737 Lemon juice 2 314 0 2804 Lettuce 1.22 0 32 2 92 0.1982 Levulose13 100.0 3.729 Maltose-dextrose mixture . (15) 3.018 Mayonnaise 1.1* 86. 44 0.24 8.197 Milk, skim 3.29 0.32 5. 12 0.3469 Milk, whole 3.32 4.02 5 O2 0.7162 Plasmon 74 5 0 2 6 9 3 786 Plasmon, graham biscuit. Plasmon, milk biscuit. . . . Popcorn 14.3 18.7 10.9 10. 016 10. 016 5 O2 69. 24 65. 04 78. 72 4.355 4.363 4.255 Potato chips 5 517 39. 82 46 72 5 6049 Used for E. H. B., A. H. M., and A. W. W. Do 4.8 37 6 39 6 5 3164 Analyzed for J. J. C., Mar. 12, 1910. Do 3 0 52 5 42 I9 6 7344 Analyzed for L. E. E., Mar. 14, 1910. Do 4 7 39 2 38 2 5 4024 Analyzed for J. R., Mar. 21, 1910. Do 4.218 37. 718 42. 118 5 . 4024 Rice (boiled) 1 9 0 I2 14 O4 0 662 Sucrose 100 0 3 960 JFor composition of mixed diets used in the research see table 235, p. 310. 2At water and Bryant, U. S. Dept. Agr., Office Exp. Stas. Bull. 28, 1906. 3Average value excluding that for A. W. W., May 25, 1907. 4Computed. 'Average value; when available actual determinations substituted for average and fuel values recomputed. 'Average of determinations for E. H. B., Apr. 8, 1907, and A. H. M., Apr. 29, 1907, with whom the actual determinations of protein were used and fuel values computed accordingly. For data regarding creatinine and creatine, see pp. 160 and 161. 'Average of determinations obtained in experiments other than those with E. H. B. and A. H. M. Actual determinations used when available and fuel values recomputed. 'Benedict, Carnegie Inst. Wash. Pub. No. 77, 1907, p. 203; in calculating protein from nitrogen the usual factor, 6.25, was used. 'Average value; determined values substituted when available. l°Also used for Prof. C. Nov. 20 and Nov. 22, 1909, in experiments with sucrose. "Average of determinations obtained for A. L. L. and A. H. M., with whom the actual determinations of protein and energy were used. "Average value, not including determinations used in first average for cream. "Emery and Benedict, Am. Journ. Physiol., 1911, 28, p. 301. 14Also 7.5 p. ct. citric acid. Atwater and Bryant, loc. cit. 15Four analyses made elsewhere on samples of this product show on the average 39 p. ct. of maltose, 27 p. ct. of dextrose and 34 p. ct. of water. "Assumed. "Determined on sample for A. W. W., Apr. 25, 1907. "Average of all values obtained for potato chips, excepting those included in first average; determined values substituted when available and fuel values recomputed. GENERAL DETAILS. 125 TABLE 51. — Statistics of age, height, and weight of subjects used in experiments following the ingestion of food. Subject. Occupation. Average age. Height. Average body- weight without clothing. Middletown: E H B College student years. 23 cm. 174 kilos. 73 H R D Do 18 171 58 H C K Do 22 181 74 ALL Do (251 166 /681 A H M Do \26/ 25 179 \74r 66 N. M. P. Do 22 177 65 Dr. R Physician 26 168 50 A. W. W College student 23 173 58 D W Do 22 180 76 H B W Do. . 20 162 62 Boston: H. H. A Medical student 21 164 62 K. H. A Laboratory assistant 26 182 66 F. G. B Chemist 40 183 83 J. C. C. College student 22 173 55 J. J. C Laboratory assistant 27 175 64 J. P. C. Medical student 23 169 73 Prof. C. Physiologist 36 169 83 T. M. C. Chemist 32 166 48 \ G. E Do. 26 169 57 H G. E. Tinsmith . 21 183 65 LEE Chemist . . . 31 175 60 A. F Student 25 175 66 A. F. G Laboratory assistant 24 175 54 V. G Do 17 162 55 C. H. H Do 19 169 55 Dr H Professor 48 182 66 H. L. H Chemist 24 172 60 P. F. J Laboratory assistant 20 167 57 B. M. K Medical student 27 163 51 D. M Do 22 171 63 D. J. M Laboratory assistant 20 175 58 F. M. M. Do 17 173 61 J. F. M . . College student 20 181 77 J K M Laboratory assistant . 23 173 61 \. J. O Baseball player 30 180 69 Dr. P. R Physician 41 164 55 J. R Chemist 27 182 69 Dr. S Professor 43 181 59 H F. T Dental student 32 179 58 'For years 1906 and 1907, respectively, because of marked difference in physical characteristics of subject. i. e., that obtained on the same day, is recorded for comparison. The period between the time the subject finished eating and the beginning of each experimental period after food is shown, also the total amount and the increase over the basal value for each of the three factors of metabolism (carbon-dioxide production, oxygen consumption, and heat production) ; the respiratory quotients are included in the tables only 126 FOOD INGESTION AND ENERGY TRANSFORMATIONS. when significant. If available, the nitrogen in the urine excreted during the food periods is given, either as an average figure with the food data at the head of the table or for the individual periods in a separate column. The tables for the respiration experiments give the data for the diet, also the average basal values per minute for the gaseous exchange, the computed heat production, the respiration rate, and the pulse rate. The time of beginning each period of measurement after food and the results of the observations are shown, with the addition in some cases of the values for the inspiratory ventilation. While the increments in the metabolism have not been calculated, they are readily noted by a comparison of the average basal values with the data recorded for each period following the ingestion of food. The time when the food was taken is given in a footnote. In both the calorimeter and respira- tion experiments the subjects usually ate the food in 15 or 20 minutes; if longer than this was required, the time thus occupied is stated in a footnote. METABOLISM DURING CHEWING. Of the various processes classified by Professor Armsby1 as prior to actual digestion, the work of prehension is hardly suitable for experi- mental study, since it would vary greatly with different individuals and with the different kinds of food consumed. On the other hand, mas- tication is a physiological function accompanying all ingestion of food. Indeed, a cult with many adherents has been established to advocate prolonged mastication. Hence information regarding the probable energy transformations as a result of mastication has unusual interest. To study this question, a series of experiments was made in which the subject chewed gum for a considerable length of time. This study was supplemented by a second series of experiments in which a rubber stopper was substituted for the chewing gum. STATISTICS OF EXPERIMENTS. The calorimeter experiments included 3 experiments with the respira- tion calorimeter at Middletown, Connecticut (tables 52 to 54), 4 with the chair calorimeter (tables 55 and 57 to 59) and 1 with the bed calorimeter in Boston, Massachusetts (table 56). In all of these the subject chewed gum. In addition, 5 respiration experiments were made with the subject chewing gum (tables 60 to 64) and two respira- tion experiments in which a rubber stopper was chewed vigorously (tables 65 and 66). A summary of the values obtained for the heat production in these experiments is included in tables 67 and 68. 'Armsby, The principles of animal nutrition, 2d ed., 1906, p. 374. METABOLISM DURING CHEWING. 127 For the respiration experiments the output of heat was computed by the indirect method. These experiments consisted of two series of periods, in the first of which the subject was without food and did no chewing. As the measurements of the metabolism were not con- tinuous, it was necessary to compute the values given in tables 67 and 68 for the total increment due to chewing by the best method obtainable and to make certain assumptions. Tables 60 to 66 show both the average heat production for the periods without food or chewing, {. e., the basal value for the day, and the heat output for each of the periods with chewing. The increase in the metabolism in the periods with chewing has been obtained by comparing the basal value for the day with the heat computed for each period. These increments of heat represent the results of two to four periods in which the metabolism was measured. The total time of chewing in the several respiration experiments varied from 53 minutes to 2 hours 19 minutes; the total duration of the measurement of the metabolism (not continuous) was from 30 to 60 minutes. In computing the total increment in the metabolism due to chewing (see table 68), it was assumed that the increase was coincident with the beginning of chewing. It was furthermore assumed that the rate of increase in the periods between the beginning of chewing and the begin- ning of the measurements (6 to 14 minutes), also in the intervals between the periods of measurement (6 to 40 minutes), was the same as that in the measured periods and that the average increment obtained for these periods represents the rate of increase in the metabolism for the total time of observation — i. e., from the beginning of chewing to the end of the last period. The total increment in the metabolism for this time was therefore computed by direct proportion. For example, in the experiment with V. G., January 5, 1911 (see table 62, page 133), the average basal value for the heat output per min- ute obtained in periods without food and without the work of chewing, was 1.13 calories. The subject began chewing 10 minutes before the measurements of the metabolism commenced. The values obtained for the respective chewing periods were 1.46, 1.52, 1.43, and 1.32 cal- ories for a total period of measurement of 53 minutes. The average increment in the metabolism during the measured periods of chewing was therefore 0.30 calorie per minute. Using this value and the total time of chewing, that is, the period from llhllm a. m. to Ih30m p. m., or 2 hours 19 minutes, the total increase in the metabolism (139 X 0.30) was computed to be 42 calories. The basal value corre- sponding to this period (139 by 1.13) was 157 calories. The percentage increase in the metabolism (42 -J- 157) was therefore 27 per cent. Statistical data not included in the tables or in the discussion are given for all of the experiments in the following paragraphs. The data for pulse rate and respiration rate represent averages of the indi- 128 FOOD INGESTION AND ENERGY TRANSFORMATIONS. vidual records for the basal and chewing periods. Records of the body- temperature, when available, were made with the rectal thermometer at the beginning of the periods and at the end of the experiment. Analyses of chewing gum give 62 to 69 per cent of soluble carbohy- drates. When the basal values were determined immediately before the chewing periods, the times given include both basal and chewing periods. CALORIMETER EXPERIMENTS. A. L.L.,8}>40ma.m.to4h40mp.m., Aprils, 1906. 67.6 kilograms. — Urinated at 4h42m and 7 p. m. Studied most of time and very quiet. Chewed rapidly and regularly. Basal periods: body-temperature, 36.69° and 36.59° C.; pulse rate, 57; respiration rate, 18. Chewing periods: body-temperature, all records, 36.65° C.; pulse rate, 58; respiration rate, 19. H. R. D., 8h37m a. m. to 4h37m p. m., April 4, 1906. 58.2 kilograms.— Uri- nated at 7h15m a. m. (after enema) and 4h48m p. m. Sat quietly reading. Rate of chewing, 72 to 107 per minute, first chewing period; 81 to 85 per minute, second chewing period. Basal periods: body-temperature, 36.73° and 36.67° C.; pulse rate, 69; respiration rate, 18. Chewing periods: body-tem- perature, 36.63°, 36.76°, and 36.76° C.; pulse rate, 69; respiration rate, 19. H. B. W., 8h05m a. m. to 4h05m p. m., April 26, 1907. 62.6 kilograms.— Urinated and defecated without enema before coming to laboratory. Very quiet in first basal period, but less quiet in second period; increasingly restless in chewing periods. Chewed steadily most of time; rate 64 to 96 per minute. Basal periods: body-temperature, 36.83° and 36.68° C.; pulse rate, 64; respi- ration rate, 18. Chewing periods: body-temperature, 36.74°, 36.75°, and 36.76° C.; pulse rate, 66; respiration rate, 18. J. J. C., 8h14m a. m. to 12*14m p. m., March 25, 1910. 64.8 kilograms.- Urinated 5h30m a. m., 8h35m a. m., and 12h35m p. m. Reported asleep 9h08m, 9h20m, and 9h40ra a. m. Basal periods: pulse rate, 60; respiration rate, 18. Chewing periods: pulse rate, 63; respiration rate, 19. V. G., 9h12m a. m. to 2^04m p. m., December 19, 1910. 55 kilograms. — In bed calorimeter. Was quiet throughout experiment except for turning over at beginning of second basal and last two chewing periods; had to be awakened several times in second basal period, but awake most of third basal period. Complained of being warm, but temperature of chamber did not exceed 21° C. at any time. Basal periods: pulse rate, 69; respiration rate, 21. Chewing periods: pulse rate, 79; respiration rate, 22. V. G., 9h07m a. m. to 12h15m p. m., January 2, 1911. 56.3 kilograms.— Very quiet at beginning of basal periods, but most of experiment restless; very rest- less in last chewing period, owing to pain in stomach. Basal periods: pulse rate, 62; respiration rate, 20. Chewing periods: pulse rate, 63; respiration rate, 19. T. M. C., 8h25m a. m. to Ilh28m a. m., January 3, 1911. 47.7 kilograms.— Urinated at 7h15m a. m. Read quietly. Rate of chewing approximately two movements of jaws a second. Basal periods: pulse rate, 68; respiration rate, 15. Chewing periods: pulse rate, 77; respiration rate, 17. T. M. C., 8h43m a. m. to 12h30m p. m., January 7, 1911. 48 kilograms.- Urinated 6h45m a. in. and Ih44m p. m. Very quiet throughout experiment. Rate of chewing, 100 to 106 in first chewing period and 88 to 100 in second chewing period. Basal periods: pulse rate, 68; respiration rate, 15. Chewing periods: pulse rate, 78; respiration rate, 16. METABOLISM DURING CHEWING. 129 TABLE 52.— A. L. L., April 3, 1906. Sitting. Chewing gum (15 grams). Nitrogen in urine, 0.65 gram1 per 2 hours. Basal values per 2 hours (April 3, 1906) : COs, 49 grams; 62, 43 grams; heat, 147 cals. Period (duration of chewing). Carbon dioxide. Oxygen. Heat. Total. Increase. Total. Increase. Total. Increase. 2 hours grams. 56 53 grams. 7 4 grams. 47 47 grams. 4 4 cals. 153 158 cals. 6 11 2 hours Total (4 hrs.) Basal values 109 98 11 94 86 8 311 294 17 'Sample included amount for about 7f hours, without food, preceding and following the periods of chewing. TABLE 53.— H. R. D., April 4, 1906. Sitting. Chewing gum (15 grams). Nitrogen in urine, 0.52 gram1 per 2 hours. Basal values per 2 hours: CO2, 46 grams (Apr. 4, 1906) ; O2, 42 grams (Feb. 6 to Apr. 20, 1006) ; heat, 148 cals. (Apr. 4, 1906). Period (duration of chewing). Carbon dioxide. Oxygen. Heat. Total. Increase. Total. Increase. Total. Increase. 2 hours grams. 51 48 grams. 5 2 grams. 44 41 grams. 2 -1 cals. 151 142 cals. 3 -6 2 hours Total (4 hours) 99 92 7 85 84 1 293 296 -3 Basal values 'Sample included amount for about 5j hours, without food, preceding the periods of chewing. TABLE 54— #. B. W., April 26, 1907. Sitting. Chewing gum (80 grams). Nitrogen in urine, 0.87 gram1 per 2 hours. Basal values per 2 hours (Apr. 26, 1907) : COa, 57 grams; O2, 50 grams; heat, 166 cals. Period (duration of chewing) . Carbon dioxide. Oxygen. Heat. Total. Increase. Total. Increase. Total. Increase. 1 hour 51 minutes ... grams. 542 57 grams. 1 0 grams. 47* 51 grams. 1 1 cals. 1543 171 cals. 0 5 2 hours Total (3 hrs. 51 min.) 111 110 1 98 96 2 325 320 5 Basal values. 'Sample included amount for about 5 \ hours, without food, preceding the periods of chewing. 'Computed from result for actual period of 2 hours by deducting basal value equivalent to 9 minutes at beginning of experiment when subject was not chewing. 130 FOOD INGESTION AND ENERGY TRANSFORMATIONS. TABLE 55.— J. J. C., March 25, 1910. Sitting. Chewing gum.1 Nitrogen in urine, 0.49 gram2 per hour. Basal values per hour (Mar. 25, 1910): CC>2, 25.5 grams; Oz, 21 grams; heat,* 79 cals. ; respira- tory quotient, 0.88. Nitrogen in urine, 0.30 gram per hour. Period (duration of chewing). Carbon dioxide. Oxygen. Heat,3 Respira- tory quotient. Total. Increase. Total. Increase. Total. Increase. 48 minutes .... ... grams. 23. 54 28.0 grams. 3.0 2.5 grams. 20. 54 22.5 grams. 3.5 1.5 cals. 644 77 cals. I -2 0.85 .90 60 minutes Total (1 hr. 48 min.) Basal values 51.5 46.0 5.5 43.0 38.0 5.0 141 142 -1 1 Amount not recorded. 2Sample included amount for if hours, without food, preceding the periods of chewing. 3Heat eliminated corrected for change in body-weight, but not for change in body-temperature. 4Computed from result for actual period of 1 hour by deducting basal value equivalent to 12 minutes at beginning of experiment when subject was not chewing. TABLE 56.— V. G., December 19, 1910. Lying. Chewing gum.1 Nitrogen in urine, 0.32 gram2 per hour. Basal values per hour (Dec. 19, 1910) : COj, 25.5 grams; Oa, 22 grams; heat,' 67 cals.; respiratory quotient, 0.85. Period (duration of chewing) . Carbon dioxide. Oxygen. Heat.3 Respira- tory quotient. Total. Increase. Total. Increase. Total. Increase. 32 minutes grams. 14. 54 20.5 31.0 grams. 1.0 1.5 2.5 grams . 11. 54 16.5 28.0 grams. 0.0 0.0 3.5 cals. 41< 54 92 cals. 5 4 17 0.90 .89 .81 45 minutes 67 minutes Total (2 hrs. 24 min.). . . Basal values 66.0 61.0 5.0 56.0 52.5 3.5 187 161 26 .... 'Amount not recorded. JSample included amount for 4 hours, without food, preceding the periods of chewing. 3Heat eliminated corrected for change in body-weight, but not for change in body-temperature. ^Computed from result for actual period of 45 minutes by deducting basal value equivalent to 13 minutes at beginning of experiment when subject was not chewing. METABOLISM DURING CHEWING. 131 TABLE 57. — V. G., January 2, 1911. Sitting. Chewing gum (about 6 grams). Nitrogen in urine, 0.39 gram1 per 45 minutes. Basal values per 45 minutes (January 2, 1911): CC>2, 22.5 grams; Oz, 19 grama; heat,5 62 cals. respiratory quotient, 0.87. Period (duration of chewing). Carbon dioxide. Oxygen. Heat.2 Respira- tory quotient. Total. Increase. Total. Increase. Total. Increase. 45 minutes . . . . grams. 21.5 22.5 grams. -1.0 0.0 grams. 19.5 17.5 grams. 0.5 -1.5 cals. 63 60 cals. 1 -2 0.80 .93 45 minutes Total (1 hr. 30 min.) Basal values 44.0 45.0 -1.0 37.0 38.0 -1.0 123 124 -1 'Sample included amount for about 3 hours, without food, preceding and following the periods of chewing. *Heat eliminated corrected for change in body-weight, but not for change in body-temperature. TABLE 58.— T. M. C., January 3, 1911. Sitting. Chewing gum.1 Nitrogen in urine, 0.27 gram2 per 45 minutes. Basal values per 45 minutes (January 3, 1911): CC>2, 14 grams; Oj, 13 grams; heat,3 47 cals.; respiratory quotient, 0.79. Period (duration of chewing). Carbon dioxide. Oxygen. Heat.3 Respira- tory quotient. Total. Increase. Total. Increase. Total. Increase. 38 minutes grams. 14. 54 17.5 grams. 2.5 3.5 grams. 11. 04 14.5 grams. 0.0 1.5 cals. 414 50 cals. 1 3 0.94 .88 45 minutes Total (1 hr. 23 min.) Basal values 32.0 26.0 6.0 25.5 24.0 1.5 91 87 4 'Amount not recorded. 2Sample included amount for about 2f hours, without food, preceding the periods of chewing. 'Heat eliminated corrected for change in body-weight, but not for change in body-temperature. 'Computed from result for actual period of 45 minutes by deducting basal value equivalent to 7 minutes at beginning of experiment when subject was not che wing. 132 FOOD INGESTION AND ENERGY TRANSFORMATIONS. TABLE 59.— T. M. C., January 7, 1911. Sitting. Chewing gum.1 Nitrogen in urine, 0.19 gram2 per 45 minutes. Basal values per 46 minutes (January 7, 1911) : CO2, 14 grams; Ch, 12.5 grams; heat,1 42 cals. ; res- piratory quotient, 0.80. Period (duration of chewing). Carbon dioxide. Oxygen. Heat.3 Respira- tory quotient. Total. Increase. Total. Increase. Total. Increase. 38 minutes grams. 14. 04 17.0 grams. 2.0 3.0 grams. 11.5* 15.0 grams. 1.0 2.5 cals. 364 48 cals. 1 6 0.87 .82 45 minutes Total (1 hr. 23 min.) 31.0 26.0 5.0 26.5 23.0 3.5 84 77 7 Basal values 'Amount not recorded. 'Sample included amount for about 5j hours, without food, preceding and following th« periods of chewing. 'Heat eliminated corrected for change in body-weight, but not for change in body- temperature. 'Computed from result for actual period of 45 minutes by deducting basal value equivalent to 7 minutes at beginning of experiment when subject was not chewing. RESPIRATION EXPERIMENTS. T. M. C., 12 noon to 12h50m p. m., December 17, 1910.— Light breakfast at 7h30m a. m. (two small slices toasted and buttered white bread and cupful of coffee, with cream and sugar). Rate of chewing, 68 to 86 per minute in first period, 74 to 87 per minute in second period ; difficult for subject to keep mouth closed when chewing. J. J. C.,9^27m a. m. to Ih55m p. m., January 4, 1911. 64.6 kilograms. — Head confined in wooden head-rest to prevent its moving out of position during sleep. Slept a few minutes in first basal period and nearly all of third basal period. Adhesive plaster over lips in basal periods. Rate of chewing, 80 to 92 per minute; in second chewing period, stopped chewing once and opened mouth for about 3 seconds. Nitrogen in urine per hour, 8 a. m. to 5h10m p. m., 0.37 gram. V. G., Sh3»m a. m. to Ih30m p. m., January o, 1911. 56 kilograms.— Asleep in second basal period; second chewing period shortened to 7 minutes, as subject was dizzy and had some difficulty in breathing; also dizzy last two minutes of third chewing and at end of fourth chewing periods. Rate of chewing, 46 to 75 per minute. Urinated at 7h50m a. m. and urinated and defe- cated at 2h40m p. m. Nitrogen in urine per hour, 7h50m a. m. to 2h40m p. m., 0.33 gram. F. G. B., S]tW" a. m. to 10*0;')™ a. m., January 9, 1911. 83.5 kilograms.- Urinated at 7h44m a, in., 8h28In a. m., and 9h24m a. m. Rate of chewing. 03 to 103 per minute in first chewing period, 100 to 104 per minute in second chewing period. F. G. B., ll}USm a. m. to ll*4om a. m., May 5, 1911. Chewing periods fol- lowed water-drinking experiment of same date (see table 79, page 147); for data regarding basal period, see statistics for that experiment. Chewed with mouth closed; rate of chewing, 90 to 95 per minute in first period and 112 to 114 per minute in second period. Nitrogen in urine per hour, 10h54m a. m. to Ilh47m a. m., 0.41 gram. V. G., Ilh26m a. m. to 12*31™ p. m., January 31, 1911. 54.9 kilograms.- Chcwing periods followed water-drinking experiment of same date (see table METABOLISM DURING CHEWING. 133 74, page 146); for data regarding basal periods, see statistics for that experi- ment. Opened mouth several times during chewing. Nitrogen in urine per hour 7h45m a, m. to 12h50m p. m., 0.32 gram. J. J. C., lhOSm p. m. to 2*09m p. m., February 7, 1911. 63.9 kilograms.- Chewing periods followed water-drinking experiment of same date (see table 75, page 146) ; for data regarding basal periods, see statistics for that experi- ment. Nitrogen in urine per hour, 7h30m a. m. to 2h16m p. m., 0.41 gram. TABLE 60. — T. M. C., December 17, 1 91 0. Chewing gum (6 grams). Lying. (Values per minute.) Basal values (Nov. 14 and 16, 1910): CO2, 163 c.c.; O2, 187 c.c.; heat (computed), 0.91 cal.; average pulse rate, 72; average respiration rate, 13. Time. Average respiration rate. Carbon dioxide. Respiratory quotient. Oxygen. Average pulse rate. Heat (computed). Chewing gum:1 12 noon 16 c.c. 177 0.84 c.c. 210 69 cats. 1.02 12h35mp.m 15 171 .80 213 70 1.02 Subject began chewing at Ilh50m a. m. TABLE 61. — J. J. C., January 4, 1911. Chewing gum (9 grams). Lying. (Values per minute.) Time. Average respiration rate. Carbon dioxide Respiratory quotient. Oxygen. Average pulse rate. Heat (computed). Without food : Av. of 3 periods 16 c.c. 201 0.93 c.c. 217 63 cals. 1.08 Chewing gum:1 12h21mp.m 17 239 70 1.30 12 47 pm. 18 228 69 1.24 1 08 p.m 19 230 72 1.25 1 40 p.m .... 19 231 69 1.25 Subject began chewing at 12h07m p. m. TABLE 62. — F. (?., January 5, 1911. Cheioing gum.1 Lying. (Values per minute.) Time. Average respiration rate. Carbon dioxide. Respiratory quotient. Oxygen. Average pulse rate. Heat (computed). Without, food : Av. of 3 periods Chewing gum ? Ilh21ma.m. . 20 17 c.c. 205 269 0.90 c.c. 229 59 88 cals. 1.13 1 46 11 51 a.m 18 281 84 1 52 12 19 p.m 18 263 86 1.43 1 15 p.m 19 243 77 1.32 Amount not recorded. 'Subject began chewing at llhllm a. m. 134 FOOD INGESTION AND ENERGY TRANSFORMATIONS. TABLE 63. — F.G.B., January 9, 1911. Chewing gum (3 grams) . Lying. (Values per minute.) Time. Average respiration rate. Carbon dioxide. Respiratory quotient. Oxygen. Average pulse rate. Heat (computed) . Without food : Av. of 2 periods 14 c.c. 244 0 94 c.c. 259 68 cals. 1 29 Chewing gum :l 9h22ma.m. .... 15 254 88 288 73 1 41 9 50 a.m 15 270 .92 295 74 1.46 Subject began chewing at 9h08m a. m. TABLE 64. — F. G. B., May 5, 1911. Cheiving gum (6 grams). Lying. (Values per minute.) Time. Average respiration rate. Carbon dioxide. Respiratory quotient. Oxygen. Average pulse rate. Heat (computed). Without food: Av. of 2 periods 13 c.c. 207 0 85 c.c. 243 62 cals. 1.18 Chewing gum :l Ilh03ma.m 15 237 86 274 64 1.34 1 1 30 a.m . .... 11 259 88 296 65 1 45 1Subject began chewing at 10h52m a. m. TABLE 65. — V.G.,Janvary81,1911. Chewing rubber stopper. Lying. (Values per minute.) Time. Average respiration rate. Carbon dioxide. Respiratory quotient. Oxygen. Average pulse rate. Heat (computed). Without food: Av. of 3 periods 19 c.c. 190 0 84 c.c. 227 59 cals. 1 10 Chewing :' Ilh26ma.m 19 213 68 1 22 11 51 a.m 19 218 69 1 25 12 16 p.m 18 222 69 1 27 Subject began chewing stopper at Ilh20m a. m. TABLE 66. — J.J.C., February 7, 1911. Chewing rubber stopper . Lying. (Values per minute.) Time. Average respiration rate. Carbon dioxide. Respiratory quotient. Oxygen. Average pulse rate. Heat (computed). Without food: Av. of 3 periods 17 c.c. 183 0.80 c.c. 229 65 cals. 1 10 Chewing :l Ib03mp.m 20 222 81 273 67 1 31 1 31 p.m 21 215 77 278 71 1 32 1 54 p.m 19 208 70 1 26 •Subject began chewing stopper at 12h50m p. m. METABOLISM DURING CHEWING. 135 TABLE 67. — Increase in metabolism of subjects drinking water, coffee, and beef tea, arul chewing gum. (Calorimeter experiments; subject sitting.)1 Group and subject. Date and place of experiments. Amount of material. Approximate temperature of material. Duration of period. Basal value for period. Increment of heat. Amt. Per cent of basal value. Chewing gum : A. L. L Middletown. Apr. 3, 1906 Apr. 4, 1906 Apr. 26, 1907 Boston. Mar. 25, 1910 Dec. 19, 19103 Jan. 2, 1911 Jan. 3, 1911 Jan. 7, 1911 Middletown. Mar. 16, 1907 Mar. 27, 1907 Boston. Jan. 10, 1911 Jan. 12, 1911 Jan. 13, 1911 Middletown. Apr. 12, 1907 Apr. 19, 1907 Middletown. Apr. 8, 1907 Apr. 29, 1907 May 2, 1907 May 9, 1907 May 10, 1907 Boston. May 12, 1910 May 13, 1910 grams. 15 15 30 6 1,584 3,935 1,547 1,800 1,800 2945 1,0736 892 1,143 2,056 1,605 892 1,222 314 °C. 22 22—11 21 22 21 72 56 to 66 82 22 22 to 7 54 50 15 to 38 44.1 hrs. min. 4 O2 4 O2 3 512 1 482 2 242 1 302 1 232 1 232 8 0 8 0 2 15 2 15 2 15 8 0 8 0 8 0 8 0 8 0 8 0 8 0 4 0 4 0 cals. 294 296 320 142 1613 124 87 77 656 320 177 138 168 620 656 716 656 620 620 60S8 316 320 cals. 17 -3 5 -1 263 -1 4 7 24 -19 6 22 26 -18 73 -11 13 4 22 20s -1 -8 6 -1 2 -1 16 -1 5 9 4 -3 3 16 15 -3 11 -2 2 1 4 3 0 -3 H. R. D H. B. W J. J. C V. G V. G T. M. C T. M. C . \Vater:4 A. H. M A. W. W . . . J. J. C T. M. C. J. J. C Coffee and sugar: A. W. W A. H. M Beef tea:7 E. H. B A. H. M A. W. W A. W. W... A. H. M J. J. C J. R 'Except in experiment with V. G., Dec. 19, 1910. 'Period here given is the actual time of chewing. 'Subject in bed calorimeter. 'Taken in varying amounts at intervals during experiments. For details, see tables 69 to 73. 'Subject finished drinking coffee 13 minutes after beginning of experiment. 'About 250 grams at beginning of each hour in first 4 hours of the experiment. 'Subject finished drinking beef tea from 14 to 38 minutes after the beginning of the respective experiments in the Middletown series; from 25 to 31 minutes before the experiments in the Boston series. 'Obtained by indirect calorimetry. 136 FOOD INGESTION AND ENERGY TRANSFORMATIONS. TABLE 68. — Increase in metabolism of subjects drinking water, coffee, and beef tea, and chewing gum. (Respiration experiments; subject lying.) Group and subject. Date. Amount of material. Temperature of material. Duration of period.1 Basal value for period (computed). Increment of heat (computed). Amt. Per cent of basal value. Chewing gum :2 T. M. C 1910. Dec. 17 1911. Jan. 4 Jan. 5 Jan. 9 May 5 Jan. 31 Feb. 7 Jan. 31 Feb. 7 Mar. 24 Mar. 27 Mar. 28 May 5 Mar. 9 Mar. 21 Mar. 23 Mar. 24 Mar. 25 Mar. 27 Jan. 25 Jan. 26 Jan. 27 Feb. 2 Feb. 3 Feb. 8 yraius. 6 9 (3) 3 6 200 300 325 325 325 500 325 325 325 325 325 312 400 400 400 400 269 350 °C. 50.5 57.4 58.0 53.0 55.0 11.0 56 . 2 to 53 . 3 (") (4) 60.0 60.0 52.0 53 . 0 to 50 . 0 55 . 2 to 53 . 6 52.8 to 52.0 61.4 to 59.0 58.7 to 60.0 55 . 4 to 50 . 0 hrs. min. 1 0 1 48 2 19 .. 57 . . 53 1 11 1 19 .. 56 1 26 1 59 1 16 2 43 .. 50 5 29 3 28 3 50 1 31 2 14 2 22 4 57 6 25 5 52 6 5 6 48 4 55 cols. 55 117 157 74 63 78 87 62 95 124 81 168 59 352 233 265 95 158 152 333 420 352 361 437 298 cals. 1 10 42 8 11 11 16 -1 2 -6 0 3 1 46 22 26 2 10 13 41 33 16 21 44 17 13 16 27 11 17 14 18 -2 2 -5 0 2 2 13 9 10 2 « 9 12 8 5 6 10 fi J. J. C. . V. G . . F. G. B F. G. B Chewing stopper: V. G . . J. J. C Water: V. G J. J. C C. H. H J. P. C A. G. E . . . . F. G. B Coffee: J. J. C J. J. C L. E. E C. H. H H. L. H J. P. C . . . . Beef tea: J. J. C V. G C. H. H C. H. H V. G C. H. H . . . 'Period here given is the time between drinking of material or beginning of chewing to the end of the last period on the respiration apparatus. *One piece of chewing gum has been found to weigh 3 grams. 'Amount of gum not recorded. ^Temperature not recorded. METABOLISM DURING CHEWING. 137 DISCUSSION OF RESULTS OF CHEWING EXPERIMENTS. In two of the Middletown calorimeter experiments, slight incre- ments in the heat output were observed; the third showed a slight decrease. The data in tables 52 to 54 also show that the increments in the values for the gaseous metabolism approximated those found for the heat production. Thus the work of chewing gum performed by these subjects during a period of approximately 4 hours usually produced on the average a slight increase over the basal metabolism. In the five experiments made with the chair and bed calorimeters in Boston, the time of actual chewing was considerably shorter than in the Middletown experiments, being approximately If to 2f hours in duration. In two of the experiments there was practically no varia- tion in the metabolism; the other three experiments showed an incre- ment of 5, 9, and 16 per cent, respectively. In one of these experi- ments, that with T. M. C. on January 7, 1911, the increment in the heat production was actually somewhat less than the increment noted in the gaseous metabolism, yet it points towards a true increase in the metabolism. In the bed-calorimeter experiment with V. G. on Decem- ber 19, 1910, in which the high increment of 16 per cent was obtained, the increase in the heat output was somewhat higher than that shown for the carbon-dioxide production, which was but 8 per cent, and for the oxygen consumption, which was but 7 per cent. It is thus not impossible that errors in the measurement of the heat production may account for the abnormally high percentage increase in this factor. Disregarding the heat value obtained in this experiment with V. G. and substituting that obtained for the gaseous metabolism of about 8 per cent, the increment in the calorimeter experiments due to chewing gum will average approximately 3 per cent, with wide variations which include three negative values. Measuring the metabolism with a respiration apparatus during the chewing of gum has certain technical difficulties which at first were thought to be insurmountable. By using nosepieces instead of a mouthpiece and giving careful instructions to the subjects, it was pos- sible to make five experiments with four subjects. In all of the respira- tion experiments it was necessary to obtain the heat output by the indirect method of computing it from the gaseous metabolism. In considering the results of the chewing experiments, therefore, it is especially important to note any possibility of loss of carbon dioxide or intake of oxygen through the mouth during chewing, for naturally any leakage of air into or out of the mouth during the periods of obser- vation would cause a disturbance in the measurements of the metab- olism. If the results recorded show similar changes in the values for the carbon-dioxide production and oxygen consumption, it may be taken as an indication that there was little, if any, leakage of air 138 FOOD INGESTION AND ENERGY TRANSFORMATIONS. through the mouth. In a number of instances it was impossible to obtain an accurate measure of the oxygen consumed, owing to careless- ness on the part of the subject in opening the mouth during chewing. This was especially true with the subjects V. G. and J. J. C. On the other hand, F. G. B. and T. M. C. took especial care to prevent such losses and the respiratory quotients found indicate that there was no disturbance and no appreciable leak. Hence we may properly assume that there was an actual increment in the metabolism which was meas- ured with a considerable degree of accuracy. The summary of the results of the respiration experiments given in table 68 shows in all cases measurable increases in the metabolism, these varying from 11 to 27 per cent. In the experiments in which the oxygen measurement was lost, due to the carelessness of the subject in opening the mouth while chewing, the carbon-dioxide measurements were used for computing the heat output. The calorific value of carbon dioxide used was the one corresponding to the respiratory quotients found prior to the chewing period, or in the few cases when quotients after the chewing period were available, an average of the two sets of quotients was used. It is of course possible that when the mouth was opened during chewing there was an increase in the carbon-dioxide excretion as a result of an excessive ventilation of the lungs. If this were the case it might account for the increase in the heat output attributed to the chewing, since in these cases the carbon-dioxide pro- duction was the only factor of metabolism available. In the experi- ments with F. G. B. and T. M. C. it is reasonably certain that there was no such loss through the mouth; the heat values could therefore be computed from the oxygen consumption. The data secured in the respiration experiments show that as a result of chewing gum the basal metabolism may be increased on the average approximately 17 per cent. The diversity of results in the calorimeter experiments may be partly explained by the fact that the experiments were carried out over a considerable period of time, and the total increment formed a relatively small proportion of the total heat measured. The conclusion is warranted, however, that chewing gum results in a positive increase in the metabolism of from 10 to 17 per cent. Although an analysis of the chewing gum shows that from 62 to 69 per cent of carbohydrates was present, it is certain that this small amount of gum — i. e., 3 to 30 grams — had no influence upon the metabolism. Supplementary evidence in regard to the work of mastication was obtained in two experiments in which the subjects vigorously chewed a rubber stopper. Both experiments were made with the respiration apparatus, unfortunately with the less reliable subjects J. J. C. and V. G. The increase in the metabolism was essentially the same as that found with the other subjects in the gum-chewing experiments, METABOLISM DURING CHEWING. 139 namely, 18 and 14 per cent, respectively, or 16 per cent on the average, thus verifying completely the more carefully planned experiments on chewing gum. It would appear from the data obtained in this study that the work of mastication, such as would be involved in chewing gum or a rubber stopper continuously, may temporarily require an increment in the metabolism of approximately 17 per cent. In general agreement with the rise in metabolism due to chewing gum and a rubber stopper, the pulse rate is found to have increased in nearly all of the experiments. In the calorimeter experiments in Boston the pulse rate increased 9 to 10 beats per minute in all except those with J. J. C., March 25, 1910, and V. G., January 2, 1911. In the experiments with the respiration apparatus an increase was found in practically all of the experiments, the increase in the averages rang- ing from 3 beats per minute with F. G. B. on May 5, 1911, to 25 beats with V. G. on January 5, 1911. At this point we are certainly justified in calling attention to the relation of the measured increase in the metabolism to the question of prolonged mastication. One of the arguments which has been advanced is that such mastication insures the absorption of a larger proportion of material from the ingested food. The fallacy of this reasoning is clearly shown when it is seen that digestion experiments have estab- lished the fact that with ordinary mastication from 90 to 95 per cent of the total energy of foodstuffs is completely absorbed. The common method of making digestion experiments is to deter- mine the protein, fat, and carbohydrates in the food eaten, and to calcu- late or determine its heat of combustion. The quantities of the same factors are determined in the feces and the ratios of the differences between these two series of values to those of the food itself are reported as the coefficients of digestibility. This method of determining the digestibility is based upon the archaic conception that feces consist primarily of the undigested residue of food. As is now known, undi- gested food forms but a small part of the feces and the ratio is in fact much higher than the commonly stated proportion of 90 to 95 per cent. Even on the basis of the older interpretation, however, the possibility of increasing the digestibility or availability of foodstuffs by extreme mastication seems very small. Furthermore, when we find that this prolonged mastication demands an excess heat production of approxi- mately 17 per cent above the basal value it is easily seen that any advantage gained from a possible increase in the digestibility of the food is more than compensated by the increase in the heat production. The conception of an increase in the digestibility and in the utilization of the energy of foodstuffs as a result of prolonged mastication thus finds no support in fact. 140 FOOD INGESTION AND ENERGY TRANSFORMATIONS. INGESTION OF WATER. Large amounts of water are regularly consumed by all individuals throughout life. Since one or more liters pass through the body in 24 hours, it is hardly conceivable that such passage is unaccompanied by energy transformations; the processes of absorption and secretion should also be taken into consideration. Furthermore, the taking of water at various temperatures frequently produces distinct subjective effects and (at times) effects of a physiological nature, such as an inclina- tion to defecation. A study of the question as to whether or not the drinking of water produces a measurable effect on the basal metabolism is therefore of prime importance. The literature is very deficient in definite information regarding the influence of water-drinking upon the metabolism. The most detailed experiments are those carried out in Rubner's laboratory by Lasch- tschenko,1 who concludes that the drinking of water at room tempera- ture (approximately 18° C.) has no influence upon the carbon-dioxide production. Water at 32° to 33° C. produced a very slight increase, but at 37° C. there was practically no increase in the carbon-dioxide production. Although the effect of water-drinking on the metabolism was studied by Berg,2 the technique was too unreliable to permit deductions from the experiments. Speck,3 who worked with a much more satis- factory technique in the experiments upon himself, concludes that drinking large amounts of water before an experiment has no influ- ence upon the oxygen consumption or carbon-dioxide production. He found, however, that when 1,250 c.c. of water were taken inside of one hour and observations were begun 30 minutes after the water had been taken, there was a noticeable rise in the metabolism; in this experiment the author noted shivering. He considered that the rise was due to a stimulus of the digestive canal, of which he became aware shortly after taking the water because of the movement of gas in the intestines. Loewy4 reports that immediately after the ingestion of 100 grams of cold water there was pressure and discomfort in the intestines, which was followed a half hour afterward by a movement of the bowels. The water caused an increase of but 2 per cent in the oxygen consump- tion with a great increase in the carbon-dioxide production. In his second experiment, in which the same amount of water was given, there was an increase of 1.5 per cent in the oxygen consumption 11 minutes after the water was taken and an increase of approximately 6 per cent 33 minutes after the drinking of the water. Thus Loewy found no definite increment in the metabolism as a result of the ingestion of pure water. Since, however, his technique as a whole has been ^aschtschenko, Arch. f. Hygiene, 1898, 33, p. 145. 'Berg. Deutsch. Arch. f. klin. Mcd., 1869, 6, p. 291. *Speck, Phyaiologie des menschlichen Athmens, 1892, p. 42. 'Loewy, Arch. f. d. ges. Physiol., 1888, 43, p. 525. INGESTION OF WATER. 141 criticized1 and a duplication of the experiments has not resulted in confirming his original observations, it is not possible to place much emphasis upon his findings. Probably no factor makes direct calorimetry so difficult in a study of the effect of food on the metabolism as does the ingestion of liquids, which are almost invariably taken into the body at temperatures con- siderably below or above the body-temperature. Water is usually taken at a temperature below that of the body, while coffee, tea, and thin extracts or soups are ordinarily taken at a temperature above. The question of the temperature adjustment inside the body is therefore somewhat important. While the rectal temperature gives a remark- ably good indication of the average body-temperature, it is by no means certain that the large amounts of heat required to warm a considerable quantity of water from 10° C. to body-temperature may not seriously disturb the temperature distribution. Indeed, in certain experiments reported from this laboratory,2 the ingestion of water produced a notice- able change in rectal temperature. The experience of Rancken, in Tigerstedt's laboratory in Helsingfors,3 shows that the rectal tem- perature, although instantly affected by the ingestion of cold liquids, returns to its original value in about 30 minutes, indicating that the equalization of temperature is rapid. In a recent series of observations Stengel and Hopkins,4 employing a thermo-couple, found that after the ingestion of 120 c.c. of ice water the temperature of the stomach dropped rapidly 1° to 14° C. and returned to normal in from 19 to 31 minutes. The experimental difficulties experienced by Lusk5 when giving a dog large amounts of water and meat just taken from an ice chest illustrate very clearly the disturbance in the heat distribution and incidentally the difficulties of determining the heat production by direct calo- rimetry when a large amount of material is ingested at a temperature considerably above or below that of the body. STATISTICS OF EXPERIMENTS. The effect of water-drinking was studied in this research in five cal- orimeter experiments and six respiration experiments. The experi- ments with the respiration calorimeter at Middletown, Connecticut, consisted of two 8-hour observations in which large amounts of water, 1,584 grams and 3,935 grams, respectively, were taken by the two subjects. (See tables 69 and 70.) With the chair calorimeter in Boston three experiments were made in January 1911, in which approximately 1,800 grams were taken by each subject. (See tables 71 to 73.) In the shorter observations with the respiration apparatus six subjects were Benedict and Emmes, Am. Journ. Physiol., 1912, 30, p. 197. 'Benedict and Slack, Carnegie Inst. Wash. Pub. No. 155, 1911, p. 73. 'Rancken, Skand. Arch. f. Physiol., 1908, 21, p. 161. 4Stengel and Hopkins, Am. Journ. Med. Sci., 1917, 153, p. 101. 5Lusk, Journ. Biol. Chem., 1915, 20, p. 555; see especially pp. 558, 576, and 615. 142 FOOD INGESTION AND ENERGY TRANSFORMATIONS. studied who were given from 200 to 500 grams of water, the tempera- ture of the water in all but one case being somewhat over 50° C. (See tables 74 to 79.) The increments in the heat production are sum- marized in tables 67 and 68. (See pages 135 and 136.) The method used for computing the increment in the water experi- ments with the respiration apparatus was that employed in the experi- ments with chewing. (See page 127.) The basal value for the day was obtained in a series of 15-minute observations when the subject was without food or water. The second series began 5 to 34 minutes after the subject had taken water; the intervals between the periods were from 14 to 29 minutes. The average heat production for the basal periods and the heat output for each of the periods with water are given in tables 74 to 79. The increment in the metabolism was obtained by comparing the average value for the basal periods with the heat production for each period after the ingestion of water. It is seen by an inspection of the tabulated data for this group of experiments that these small and in some cases negative increments in the heat production represent the results of two to four periods of measurement. The sum total of time for these measurements, which are obviously not continuous, is 30 to 60 minutes, extending over periods of 50 minutes to 2 hours and 43 minutes following the drinking of water. In calcu- lating the total increments it was assumed that the rate of increase for the time between the drinking of the water and the end of the last period was the same as that observed in the measured periods. For example, in the experiment with J. J. C., February 7, 1911 (seepage 146), the basal value for the heat production is 1.10 calories per minute and the values for the respective periods after the water was taken are 1.10, 1.14, and 1.11 calories per minute. It is thus seen that the average increase per period and per minute is equivalent to 0.02 calorie. The time between the drinking of the water and the end of the last period (Ilh05m a. m. to 12h31m p. m.) was 86 minutes. The total increment computed as heat (86 X 0.02) was thus 2 calories. The basal value for a corresponding length of time (86 X 1.10) was 95 calories; the percentage increase in metabolism (2-7-95) was, there- fore, 2 per cent. Statistical data not included in the tables or in the discussion are given in the following paragraphs for all of the experiments. The times given include both basal and water-drinking periods, when the basal values were determined immediately before the water-drinking. CALORIMETER EXPERIMENTS. A. H. M., 9h28m a. m. to 5h28m p. m., March 16, 1907. 66.3 kilograms.- Urinated shortly before 7 o'clock (after enema); attempted to urinate near beginning of each period, urinating at 9h35m a. m., 12h46m, 2h32m, 3h34m, and 5h28m p. m.; unable to urinate at end of either first or second period; some pressure from urine; some sensation of fullness from water-drinking. Drank water in each period. Stooped over in third period to pick up rubber stop- INGESTION OF WATER. 143 per from floor; reported restless in last hour of fourth period; otherwise sit- ting quietly in chair, reading much of time. Body-temperature: 37.34°, 37.30°, 37.26°, 37.41°, and 37.44° C. Pulse rate, 50; respiration rate, 18. A, W. W., 8h%4m a. ro. to 4h24m p. m., March 27, 1907. 58 kilograms.— Drank water twice in first period, four times in second, once in third, and four times in fourth period. Urinated about 7h15m a. m. (after enema), three times in second, once in third, and twice in fourth period. Activity other than indicated was small ; part of time reading. Body-temperature: 36.71°, 36.48°, 36.71°, 36.73°, and 36.73° C. Pulse rate, 57; respiration rate, 23. /. /. C., 9h08m a. m. to l*39m p. m., January 10, 1911. 63.4 kilograms.— In three basal periods went through motions of drinking water and urinating to equalize muscular activity throughout experiment; an effort was also made to minimize activity by having urine jars and drinking-water on table conven- iently placed and by use of bent-glass tube in drinking. Urinated at 7h55m and Ilh30m a. m., 12h03m, 12h55m, Ih20ra, and Ih49m p. m. Drank water three times in each of the water-drinking periods. Asleep at 10h52m a. m. ; also slept in first water-drinking period. On evening of experimental day had slight tendency to diarrhea, probably due to excessive water drinking. Basal periods : pulse rate, 68; respiration rate, 17. Water-drinking periods: pulse rate, 70; respiration rate, 19. T. M. C., 8h55m a. m. to 12h40m p. m., January 12, 1911. 47.5 kilograms.— Slightly more active in water-drinking periods than in two basal periods. Urinated at 7h15m, 10h28m, Ilh58m a. m., 12h29m, and 12h48ra p. m. In each water-drinking period subject drank water three times. Basal periods: pulse rate, 69; respiration rate, 15. Water-drinking periods: pulse rate, 70; respira- tion rate, 15. J. J. C., 8ho6m a. m. to 12h41m p. m., January 13, 1911. 64.9 kilograms. — At Ilh30m p. m. on preceding day subject ate 5 tablespoonfuls chicken salad, 1 Vienna roll, 3 cupfuls coffee, 5 macaroons, 8 or 9 lady-fingers, one large dish sherbet and ice cream, one slice walnut cake. Activity due to water- drinking and urinating in last three periods simulated in two basal periods preceding. Water taken three times in each water-drinking period. Uri- nated at 7h50m, 10h33m, Ilh14m, Ilh59m a. m., 12h18m, and 12h47m p. m. In first basal period sat quietly reading; in second basal period slept about 8 minutes shortly after period began and fell asleep again near end of period. As pulse rate was indistinct in first water-drinking period, he readjusted stetho- scope. Basal periods : pulse rate, 61 ; respiration rate, 18. Water-drinking periods: pulse rate, 58; respiration rate, 19. M., March 16, 1907. Sitting. (2-hour periods.) TABLE 69.— A. H. Water (22° C.), 1,584 grams. Basal values (March 6 and 9, 1907) : CO2, 51 grams; Oj, 46 grams; heat, 164 cals. urine, 0.96 gram per 2 hours (March 16, 1907). Nitrogen in Water Nitrogen Carbon dioxide. Oxygen. Heat. consumed.1 in urine per 2 hours. Total. Increase. Total. Increase. Total. Increase. grams. grams. grams. grams. grams. grams. cals. cals. 434 1.23 51 0 45 -1 177 13 439 1.28 52 1 44 _2 160 -4 443 1.25 53 2 47 1 175 11 268 1.32 53 2 49 3 168 4 Total 209 5 185 1 680 24 lSubject drank the respective amounts at ths beginning of the 2-hour periods. 144 FOOD INGESTION AND ENERGY TRANSFORMATIONS. TABLE 70.— A. W. W., March 27, 1907. Sitting. (2-hour periods.) Water (22° C.), about 400 grams at 11° C. in last period), 3,935 grams. Basal values (March 15 and 21, 1907) : COs, 50 grama; O-2, 41 grams; heat, 155 cala. Water Nitrogen Carbon dioxide. Oxygen. Heat. consumed.1 in urine per 2 hours. Total. Increase. Total. Increase. Total. Increase. grams. grams. grams. grams. grams. grams. cols. cala. 1,313 0.422 48 -2 34 -7 149 -6 1,021 1.06 53 3 44 3 152 -3 284 .51 47 -3 37 -4 135 -20 1,317 .80 54 4 47 6 165 10 Total .... 202 2 162 -2 601 -19 JBegan drinking water with beginning of experiment. 2 Sample includes amount for about an hour preceding experiment. TABLE 71. — J. J. C., January 10, 1911. Sitting. (45-minute periods.) Water (21° C.), 1,547 grams. Basal values (January 10, 1911): COz, 19.5 grams; Oj, 17 grama; heat,1 69 cala.; respiratory quotient, 0.84. Nitrogen in urine, 0.44 gram per 45 minutes. Water Nitrogen in urine Carbon dioxide. Oxygen. Heat.1 Respira- consumed.2 per 45 minutes. Total. Increase. Total. Increase. Total. Increase. tory quotient. grams. yra m . grams. grams. grams. grams. cals. cala. 674 0.42 21.5 2.0 20.5 3.5 68 9 0.77 375 .54 20.5 1.0 18.0 1.0 56 — 3 .82 498 .49 21.0 1.5 19.5 2.5 69 0 .79 Total 63.0 4.5 58.0 7.0 183 6 'Heat eliminated corrected for change in body-weight, but not for change in body-temperature. 2Subject drank about 175 grams of water at each interval of about 10 to 20 minutes. TABLE 72. — T. M. C., January 12, 1911. Sitting. (45-minute periods.) Water (22° C.), 1,800 grams. Ratal values (January 12, 1911): CO2, 14.5 grams; Oj, 13 grams; heat,1 46 cals.; respiratory quotient, 0.82. Nitrogen in urine, 0.21 gram per 45 minutes. Water Nitrogen in urine Carbon dioxide. Oxygen. Heat.1 Respira- consumed.2 per 45 minutes. Total. Increase. Total. Increase. Total. Increase. tory quotient. grams. gram. grams. grains. grams. grams. cals. cals. 600 0.36 15.0 0.5 16.0 3.0 57 11 0.68 600 .36 16.5 2.0 14.5 1.5 51 5 .85 600 .41 17.0 2.5 17.0 4.0 52 6 .72 Total .... 48.5 5.0 47.5 8.5 160 22 lHeat eliminated corrected for change in body-weight, but not for change in body-temperature. 'Subject drank 200 grams of water at each interval of about 15 minutes. INGESTION OF WATER. 145 TABLE 73. — J. J. C., January IS, 1911. Sitting. (45-minute periods.) Water (21°C.), 1,800 grams. Basal values: COz, 20 grams (January 13, 1911); O->, 17.5 grams (January 10-17, 1911); heat. 66 cals. (January 13, 1911); respiratory quotient, 0.85 (January 13, 1911). Nitrogen in urine, 0.38 gram per 45 minutes (January 13, 1911). Water Nitrogen in urine Carbon dioxide. Oxygen. Heat.1 Respira- consumed.2 per 45 minutes. Total. Increase. Total. Increase. Total. Increase. quotient. grams. gram. grams. grams. grams. grams. cals. cals. 600 0.45 20.5 0.5 20.0 2.5 67 11 0.75 600 .57 23.0 3.0 21.0 3.5 64 8 .80 600 .53 21.5 1.5 18.5 1.0 63 7 .84 Total . . 65.0 5.0 59.5 7.0 194 26 eliminated corrected for change in body-weight, but not for change in body-temperature. 'Subject drank 200 grams of water at each interval of about 10 to 20 minutes. RESPIRATION EXPERIMENTS. V. G., 8h41m a. m. to 11^02m a. m., January 31, 1911. 54.9 kilograms.— Previous day, low carbohydrate diet. Between supper on preceding day and 8 a. m. of experimental day, walked 1.6 miles according to pedometer. Urinated 7h45m a. m. Slept a little in first basal period, still longer in second period, very sleepy in first part of third period, but wideawake in latter part, as special efforts were made to keep him awake. Very quiet in last water-drink- ing period; asleep part of the time. Blood pressure: basal periods, 102, 107, 105 mm.; after water, 103, 100 mm. Nitrogen in urine per hour 7h45m a. m. to 12h50m p. m., 0.32 gram. J. J. C., 9h10m a. m. to 12h31m p. m., February 7, 1911. 63.9 kilograms. — Between 5 p. m., February 6, and 8 a. m., February 7, walked 1.5 miles accord- ing to pedometer. Very quiet throughout experiment; slept part of second basal period, and a little in first two periods after water. Urinated 7h30m a. m. and 2h16m p. m. Blood pressure: basal periods, 108, 111, 120 mm.; after water, 102, 105, 102 mm. Nitrogen in urine per hour 7h30m a. m. to 2h16m p. m., 0.41 gram. C. H. H., 9h16m a. m. to Ih39m p. m., March 24, 1911. 54.9 kilograms. — Urinated at 8hlom a. m. ; quiet throughout experiment. Pulse rate increased immediately after taking hot water, range between Ilh45m a. m. and 12h15m p. m. being 63 to 79. Blood pressure: basal periods, 119, 122, 120, 120 mm.; after water, 119, 115, 104 mm. Nitrogen in urine per hour 8h15m a. m. to 4 p. m., 0.27 gram. /. P. C., 9h04m a. ra* to Ilh22m a. m., March 27, 1911. 73.1 kilograms.— Mouthpiece and noseclips used instead of nosepieces ; high carbohydrate diet on day preceding experiment. Urinated at 7 a. m., Ilh53m a. m., and 2h15m p. m. Nitrogen in urine per hour 7 a. m. to Ilh53m a. m., 0.42 gram. A. G. E., 8h52m a. m. to 12h38m p. m., March 28, 1911. 56.9 kilograms.— Low carbohydrate diet day before. Awake and quiet during whole experi- ment; urinated at 7h30m a. m. and large amount at 2 p. m. Blood pressure: basal periods, 117, 116 mm.; after water, 126, 128, 119, 117 mm. Nitrogen in urine per hour 7h30m a. m. to 2 p. m., 0.48 gram. F. G. B., 9h02m a. m. to 10h48m a. m., May 5, 1911. During first period after water had strong desire to urinate; urinated at 10h21m a. m., 10h54m a. m., and Ilh47m a. m. Nitrogen in urine per hour 8h45m a. m. to 10h21m a. m., 0.57 gram; 10h21m a. m. to 10h54m a. m., 0.49 gram. 146 FOOD INGESTION AND ENERGY TRANSFORMATIONS. TABLE 74. — V. G., January 81, 1911. Lying. (Values per minute.) Water (50.5° C.), 200 c.c. Time. Average respiration rate. Carbon dioxide. Respiratory quotient. Oxygen. Average pulse rate. Heat (computed). Without food: Av. of 3 periods. . . Water:1 lOM^a.m 19 19 c.c. 190 197 0.84 .88 c.c. 227 224 59 66 cals. 1.10 1.10 10 47 a.m 18 191 .86 222 60 1.08 JTaken at 10h06m a. m. TABLE 75.— J. J. C., February 7, 1911. Lying. Water (67.4° C.), 300 c.c. (Values per minute.) Time. Average respiration rate. Carbon dioxide. Respiratory quotient. Oxygen. Average pulse rate. Heat (computed). Without food: Av. of 3 periods . . . Water:1 Ilh15ma.m 17 19 c.c. 183 197 0.80 .88 c.c. 229 225 65 66 calt. 1.10 1.10 11 46 a.m 17 192 81 237 64 1.14 12 16 p.m 17 190 .83 229 64 1.11 !Taken at Ilh05m a. m. TABLE 76.— C. H. H., March 24, 1911. Lying. Water (58° C.), 325 c.c. (Values per minute.) Time. Average respiration rate. Carbon dioxide. Respiratory quotient. Oxygen. Average pulse rate. Heat (computed) . Without food: Av. of 4 periods . . . Water:1 12h14mp.m 14 13 c.c. 178 180 0.83 .88 c.c. 214 203 62 64 cals. 1.04 0.99 12 56 p.m 12 173 85 204 63 .99 1 24 p.m 14 173 84 207 63 1.00 :Taken at ll^O"1 a. m. TABLE 77. — J. P. C., March 27, 1911. Lying. (Values per minute.) Water (53° C.), 325 c.c. Time. Average respiration rate. Carbon dioxide. Respiratory quotient. Oxygen. Average pulse rate. Heat (computed) Without food: Av. of 2 periods. . . Water:1 > • ; 10h37ma.m. 18 18 c.c. 188 186 0.86 84 c.c. 219 221 52 52 call. 1.07 1.07 11 07 a.m 19 189 86 220 51 1.07 iTaken at 10h06ra a.m. INGESTION OF WATER. 147 TABLE 78. — A. 0. E., March 28, 1911. Lying. (Values per minute.) Water (about 55° C.), 325 c.c. Time. Average respiration rate. Carbon dioxide. Respiratory quotient Oxygen. Average pulse rate. Heat (computed). Without food : Av. of 2 periods . . . Water:1 10h26ma.m 11 11 c.c. 178 176 0.84 .86 c.c. 213 205 63 64 colt. 1.03 1.00 10 58 a.m 11 175 .80 218 66 1.05 11 42 a.m 11 183 .79 231 64 1.11 12 23 p.m . 13 177 .82 217 64 1.05 at 9h55m a. m. TABLE 79.— F. G. B., May 5, 1911. Water (11° C.), 500 c.c. Lying. (Values per minute.) Time. Average respiration rate. Carbon dioxide. Respiratory quotient. Oxygen. Average pulse rate. Heat (computed). Without food: Av. of 2 periods . . . Water:1 10h03ma.m 13 13 c.c. 207 198 0.85 .80 c.c. 243 247 62 64 cols. 1.18 1.19 10 33 a.m 14 209 .85 245 60 1 19 xTaken between 9h54m and 9h58m a. m. DISCUSSION OF RESULTS OF WATER-DRINKING EXPERIMENTS. Of special significance is the fact that in the three Boston calorimeter experiments the heat output as reported is heat eliminated and not heat produced ; that is, the heat measurements have not been corrected for changes in the body- temperature. From an inspection of the data giving the increments in the water-drinking periods, it will be seen that in most cases the gaseous metabolism shows a positive increase corresponding to the increase in the heat output and in some instances it is roughly proportional to the increase in the heat. This, to a certain degree, confirms the validity of the heat measurements, even when not corrected for changes in the body-temperature. In the final summaries, given in tables 67 and 68 (see pages 135 and 136) , the total increments and the percentage increments are based solely upon the heat measurements. The values in table 67 show that in all but one of the calorimeter experiments, that with A. W. W. on March 27, 1907, there was a positive increase in the heat output as a result of taking water. In only two of the calorimeter experi- ments, those of January 13, 1911, with J. J. C., and January 12, 1911, with T. M. C., can the increments be considered as really significant, 148 FOOD INGESTION AND ENERGY TRANSFORMATIONS. these being 15 and 16 per cent, respectively. While the results of the experiment on January 13 may be open to the general criticism that J. J. C. was, as a rule, an unsatisfactoiy subject in many ways, yet so far as we can see there is nothing about the experiment which can be criticized, and we believe that the increment of 15 per cent represents a true increment. Reference to table 73 shows that in the experiment with J. J. C. on January 13, the total increase in the carbon-dioxide production was 8 per cent and in the oxygen consump- tion it was 13 per cent of the basal value. In the experiment with T. M. C. on January 12 (see table 72), the total increase in the car- bon-dioxide production was 11 per cent and in the oxygen consump- tion 22 per cent. Evidently in both these cases there were actual in- crements in the metabolism due to the drinking of water. The two experiments with the high increments were made with the chair calorimeter in Boston and in periods approximately 2| hours in length. The series of experiments with the universal respiration apparatus, in which the periods were approximately 15 minutes each but which covered a total period between the drinking of the water and the end of the last period of 50 minutes to approximately 2| hours, shows values considerably at variance with those obtained with the calorimeter. (See table 68.) In no case was the increment over 2 per cent and in two out of the six experiments there was, as a matter of fact, a slight decrease. The amount of water taken in these respiration experiments was much smaller than that taken in the calorimeter experiments, but this can not account entirely for the small increments, as the calorimeter experiment with A. W. W. on March 27, 1907, in which the largest amount of water was taken, namely, 3,935 grams, resulted in a decrease in the metabolism of 3 per cent.1 From the results of both series of experiments it is safe to conclude that when not over 500 grams of water are taken, as in the respiration experiments, the ingestion of water with a temperature of either 22° or 55° C. produces no significant increment of the basal metabolism. Since the two calorimeter experiments on January 12 and 13, 1911, apparently showed true increments in the metabolism due to water- drinking, there may be with more than 500 grams of cold water an increase as great as 16 per cent above the basal value. Although the subjective impressions of the two men showing the large increment were not recorded with sufficient detail to indicate any peculiar sensa- tions, it is not impossible that we may have here a nervous phenomenon not unlike those mentioned by Loewy. (See page 140.) The pulse was counted in a considerable number of instances; measurements were likewise made of the blood pressure by means of 'Mention should horo be made of the experiments carried out by Ranke (see table 2, p. 17) in which the carbon-dioxide production for 24 hours of fasting without water was 603.5 grams, :md on another day with the subject fasting with 2.10!) c.c. writer it was G02.0 grams. INGESTION OF WATER. 149 the Erlanger sphygmomanometer. A general inspection of these results shows nothing significant in the changes in either pulse or blood pressure as a result of the ingestion of water. In experiments of this kind one might maintain that it would be more logical to attempt a correlation of the metabolism with the total quantity of urine passed rather than with the amount of water taken, since it is conceivable that the mechanical work of the processes involved would be shown more clearly by the volume of urine excreted. As would be expected, the volume of urine increased considerably when large quantities of water were consumed, but the amounts of urine excreted were usually not abnormal, and we were unable to dis- cover any definite correlation between the volume of urine and the total metabolism. 150 FOOD INGESTION AND ENERGY TRANSFORMATIONS. INGESTION OF COFFEE. Although the earlier experimenters made but few observations on the effect of drinking hot or cold water, we find a number of studies on the effect of taking tea and coffee. Of special interest is the series of experiments made by Bocker,1 who concludes that the taking of coffee decreases both extensively and intensively the respiratory processes. Edward Smith2 has a series of observations on drinking both tea and coffee, and concludes that tea is a powerful respiratory stimulus, coffee being but little less powerful. With the technique used by both these investigators, it was not possible to study the fine differences which in later times have been found to exist ; hence their results can not be considered as conclusive. Speck3 studied the effect of coffee-drinking in two experiments and found a small but visible rise in the carbon-dioxide production and oxygen consumption, indicating to his mind a distinct stimulus to the digestive activities. Lehmann and Rohrer4 found that the volatile constituents of tea and coffee did not cause any noticeable changes in the respiration frequency. A series of papers from the Russell Sage Institute of Pathology has just appeared which includes a paper by Means, Aub, and Du Bois,5 reporting the results of a study in which four normal subjects were given from 8 to 10 grains of caffein — i. e., 8.6 milligrams per kilogram of body-weight. The authors state that the basal metabolism was increased from 7.4 to 23.5 per cent, these values representing average "peak" effects. Of special significance is the fact that there was no material change in the pulse rate. STATISTICS OF EXPERIMENTS. Our own observations with coffee include two calorimeter experi- ments made in Middletown and six respiration experiments in Boston. The results are given in tables 80 to 87 and discussed in the accom- panying text. They are also summarized in tables 67 and 68. (See pages 135 and 136.) In all of the experiments the coffee was taken hot; in the two calo- rimeter experiments a certain amount of sugar was also taken. The general plan of both series of experiments was similar to that of the water-drinking studies. The measurement of the gaseous metabolism in the respiration experiments began 6 to 32 minutes after the drinking of the coffee ; the total time between the taking of coffee and the end of the last period ranged from 1 hour 31 minutes to 5 hours 29 minutes. The method of determining the total increment in the respiration experiments was unlike that used in the chewing and water-drinking studies in that the increase was found here by measuring plotted areas 'Bocker, Beitriige zur Heilkunde, 1849, 1, p. 200. 'Smith, Phil. Trans., 1859, 149, p. 715. 'Speck, Physiologic des menschlichen Athmens, 1892, p. 42. 4Lehmann and Rohrer, Arch. f. Tlys;., 1902, 44, p. •_'(•:;. 'Means, Aub, and Du Bois, Arch. Intern. M-i 4 Hours after food FIG. 2. — Curve showing increment of heat production following ingestion of 177 grams of beefsteak in experiment with Dr. S., June 30, 1911. CALORIMETER EXPERIMENTS. A. W. W., 8*21™ a. m. to 4h21m p. m., April 12, 1907. 58.0 kilograms.- No apparent diuretic or bad effects from drinking coffee. Urinated at 7h10m a. m. (after enema) and once in every period except first; drank water at beginning of both third and fourth periods (303.5 grams in all). Less quiet in fourth period than in others. Body-temperature, 36.58°, 36.89°, 36.93°, 37.03°, and 37.05° C. Pulse rate, 62; respiration rate, 21. A. H. M., 8h09m a. m. to 4h09m p. m., April 19, 1907. 66 kilograms.- Coffee made in a percolator in proportion of one tablespoonful coffee to one cupful water; strong infusion obtained after boiling for some time. Subject directed to drink during the experiment a cupful of coffee each hour until he could take no more; was not a coffee drinker. Cupful of coffee with two tea- spoonfuls of sugar taken at 8h18m, 9h18m, 10h20m, and Ilh18m a. m., and 5.2 grams coffee, with no sugar, at 12h24in p. m. Telephoned twice in each period but last; opened food aperture, without rising from chair, twice in both first and second periods and once in third period; urinated about 4h30m a. m. and once in each period of experiment except first; activity slight otherwise; reading most of time. Said first two cupfuls tasted very good, next two cupfuls taken with difficulty, and could take but little afterwards. Slight dizziness after 12 o'clock; urinated more freely than usual but drank no water. Body-temperature: 36.86°, 36.76°, 36.92°, 36.71°, 36.76° C. Pulse rate, 63; respiration rate, 18. 'See table 215, p. 284. INGESTION OF COFFEE. 153 TABLE 80.— 4. W. W., April 12, 1907. Sitting. (2-hour periods.) Coffee (78° C.) and sugar: Amounts, 271 grams coffee, 23 grams sugar; nitrogen, 0.08 gram; total energy, 105 cals . Fuel value: Total, 105 cals.; from protein, 2 p. ct. ; from carbohydrates, 98 p. ct. Basal values (March 15 and 21, 1907) : CCh, 50 grams; Oa, 41 grams; heat, 155 cals. Time elapsed Nitrogen Carbon dioxide. Oxygen. Heat. since subject in urine finished per eating. 2 hours. Total. Increase. Total. Increase. Total. Increase . gram. grams. grams. grams. grams. cals. cals. 0 to 2 hours1. . 0.95- 54 4 48 7 167 12 2 to 4 hours . . .952 50 0 34 -7 142 -13 4 to 6 hours . . .73 48 _2 43 2 140 -15 6 to 8 hours . . .71 48 -2 41 0 153 - 2 Total . . . 200 0 166 2 602 -18 Subject finished drinking coffee 13 minutes after the beginning of this period. The drinking was done quickly. *Sample included amount for about l£ hours, without food, preceding experiment. TABLE 81.— A. H. M., April 19, 1907. Sitting. (2-hour periods.) Coffee (56 to 66.5° C.) arid sugar: Amounts, 1,011 grams coffee, 62 grams sugar; nitrogen, 0.39 gram; total energy, 300 cal«. Fuel value: Total, 296 cals.; from protein, 3 p. ct.; from carbohydrates, 97 p. ct. Basal values (March 6 and 9, 1907): COa, 51 grams; Os, 46 grams; heat, 164 cals. Coffee.1 Nitrogen in urine per 2 hours. Carbon dioxide. Oxygen. Heat. Total. Increase. Total. Increase. Total. Increase. grams. 491 grams. 1.202 grams. 68 grams. 17 grams. 54 grams. 8 cals. 185 cals. 21 577 1.24 72 21 63 17 200 36 5 1.23 55 4 46 0 167 3 Total . . . 1.11 57 6 52 6 177 13 .... 252 48 215 31 729 73 'About 250 grams at the beginning of each hour of the first two periods. 'Sample included amount for about 3f hours, without food, preceding experiment. RESPIRATION EXPERIMENTS. J. J. C., 8ho7'tt a. m. to 4h52m p. m., March 9, 1911. 64.3 kilograms.- Low-carbohydrate supper preceding day. Coffee made in proportion of two heaping tablespoonfuls of coffee to one cupful of water and boiled 10 minutes. Urinated 7h15m a. m. First basal period, awake and quiet; second, drowsy; third, very quiet, keeping awake with some difficulty; fourth, fell asleep at least once in spite of constant efforts of observer to prevent it. In periods following coffee, awake and quiet, with one decided movement in next to last period. Between sixth and seventh periods after coffee, turned on his side and generally somewhat active; between eighth and ninth periods, somewhat restless. Blood pressure: basal periods, 111, 110, 109, 110 mm.; after coffee, 123, 124, 117, 115, 117, 122, 129, 130,1 132 mm. Nitrogen in urine per hour 7h15m a. m. to 5 p. m., 0.43 gram. tingle record. 154 FOOD INGESTION AND ENERGY TRANSFORMATIONS. J. J. C., 9*22m a. m. to 8h13m p. ra., March 21, 191 1. 64.8 kilograms.— Urinated at 7h15m a. m. and 3h35m p. m. First basal period, lay quietly; second, very quiet, asleep last two minutes; third, very sleepy; fourth, fell asleep and when aroused moved a little; fifth, still drowsy and coughed once. Between second and third periods after coffee, more active than usual; in fourth period after coffee, quiet but coughed once; fifth, very quiet but awake; last period, coughed twice. Blood pressure: basal periods, 118, 110, 115, 113, 111 mm.; after coffee, 118, 123, 117,1 122,1 125, 1221 mm. Nitrogen in urine per hour 7h15m a. m. to 3h35m p. m., 0.43 gram. L. E. E , 8*42m a. m. to 2 p. m., March 23, 1911. 59.5 kilograms.— High- carbohydrate diet preceding day. Urinated at 7h45m a. m. and Ih26m p. m. A little nervous in fourth period after coffee, twitching feet and making other slight movements. Blood pressure: basal periods, 120,1 126,1 HO1 mm.; after coffee, 126, 126, 130, 130, 129, 128, 130 mm. Nitrogen in urine per hour 7h45m a. m. to Ih26m p. m., 0.52 gram. C. H. H., 2h40m p. m. to 3h50m p. m., March 24, 1911. 54.9 kilograms.— Preceded by water-drinking experiment (see table 76, page 146); for data regarding basal periods, see statistics for that experiment. Range in pulse rate between 2h24m p. m. and 2h34m p. m. (after drinking coffee), 65 to 73. Blood pressure: basal periods, 119, 122, 120, 120 mm.; after coffee, 115, 119, 1191 mm. Nitrogen in urine per hour 8h15m a. m. to 4 p. m., 0.27 gram. H. L. H., 8h30m a. m. to 12*21™ p. m., March 25, 1911. 60.4 kilograms.— Low-carbohydrate diet day preceding. Urinated at 7h40m a. m. In last basal period, some difficulty in breathing, due to slight cold; coughed once. At end of second period after coffee, very slight leak in left nosepiece. Blood pressure: basal periods, 101, 101, 102 mm.; after coffee, 107, 106,1 117 mm. Nitrogen in urine per hour 7h40m a. m. to 12h30m p. m., 0.53 gram. J. P. C., 12h10m p. m. to 2 p. m., March 27, 1911. 73.1 kilograms.— Pre- ceded by water-drinking experiment (see table 77, page 146) ; for data regard- ing basal periods, see statistics for that experiment. Blood pressure: basal periods, 100, 1021 mm. ; after coffee, 105, 125, HO,1 116 mm. Nitrogen in urine per hour Ilh53m a. m. to 2h15m p. m., 0.52 gram. TABLE 82. — J. J. C., March 9, 1911. Lying. (Values per minute.) Coffee, black (56.2° to 58.3° C.): Amount, 325 grams; nitrogen, 0.28 gram; total energy, 45 cals. Fuel value: Total, 43 cals.; from protein, 16 p. ct.; from carbohydrates, 84 p. ct. Time. Average respiration rate. Carbon dioxide. Respiratory quotient. Oxygen. Average pulse rate. Heat (computed) . Without food: Av. of 4 periods . . . With food:2 Ilh29ma.m 16 18 c.c. 184 236 0.83 96 c.c. 222 246 57 65 cals. 1.07 1 23 11 55 a.m 20 222 94 236 61 1 17 12 23 p.m 19 204 82 250 58 1 21 12 53 p.m 19 196 79 247 58 1 18 1 26 p.m 17 216 81 266 61 1 28 1 59 p.m. . . 19 200 78 255 60 1 22 2 36 p.m 19 201 78 257 57 1 23 3 55 p.m 18 193 79 243 58 1 16 4 37 p.ra 19 213 .79 268 59 1 28 'Single record. "Subject drank coffee between Ilh21m and Ilh23m a. m. INGESTION OF COFFEE. 155 TABLE 83. — J. J. C., March SI, 1911. Lying. (Values per minute.) Coffee: Amount, 325 grams; nitrogen, 0.11 gram; total energy, 17 cals. Fuel value: Total, 16 cals.; from protein, 18 p. ct.; from carbohydrates, 82 p. ct. Time. Average respiration rate. Carbon dioxide. Respiratory quotient. Oxygen. Average pulse rate. Heat (computed) . Without food : Av. of 5 periods. . . With food r1 12h07mp.m 17 21 c.c. 192 228 0.83 .90 c.c. 232 254 64 67 cals. 1.12 1.25 12 35 p.m 19 198 .84 236 63 1.14 1 04 p.m 20 215 .84 256 64 1.24 1 46 p.m 20 219 .84 261 65 1.27 2 27 p.m 21 215 .81 264 66 1.27 2 58 p.m 17 197 .78 253 62 1.21 Subject drank coffee at Ilh45m a. m. TABLE 84. — L. E. E., March 23, 1911. Lying. (Values per minute.) Coffee: Amount, 325 grams; nitrogen, 0.09 gram; total energy, 17 cals. Fuel value: Total, 16 cals; from protein, 16 p. ct.; from carbohydrates, 84 p. ct. Time. Average respiration rate. Carbon dioxide. Respiratory quotient. Oxygen. Average pulse rate. Heat (computed) . Without food: Av. of 3 periods . . . With food:1 10h31ma.m . . . 11 12 c.c. 204 214 0.86 .80 c.c. 236 267 58 54 cai*. 1.15 1.28 11 00 a.m . . 12 206 .82 251 52 1.21 11 29 a.m 11 215 .81 266 54 1.28 12 00 noon 12 212 .79 269 57 1.29 12 32 p.m 12 206 .77 268 54 1.28 1 06 p.m 11 214 .82 262 54 1.26 1 45 p.m 11 209 .78 269 55 1.28 Subject drank coffee between 10h07m and 10h10m a. m. TABLE 85. — C. H. H., March 24, 1911. Lying. (Values per minute.) Coffee (60° C.): Amount, 325 grams; nitrogen, 0.08 gram; total energy, 17 cals. Fuel value: Total, 16 cals; from protein, 14 p. ct. ; from carbohydrates, 86 p. ct. Time. Average respiration rate. Carbon dioxide. Respiratory quotient. Oxygen. Average pulse rate. Heat1- (computed) . 8&*3ta3* Without food: Av. of 4 periods . . . With food i1 2h40mp.m 14 14 c.c. 178 178 0.83 .79 c.c. 214 226 62 65 call. 1.04 1.08 3 10 p.m 14 185 .86 215 70 1.05 3 35 p.m 14 183 .85 215 70 1.05 'Subject drank coffee at 2h19m p. m. 156 FOOD INGESTION AND ENERGY TRANSFORMATIONS. TABLE 86. — H. L. H., March 25, 1911. Lying. (Values per minute.) Coffee (60° C.): Amount, 325 grams; nitrogen, 0.09 gram; total energy, 17 cals. Fuel value: Total, 16 cals.; from protein, 16 p. ct.; from carbohydrates, 84 p. ct. Time. Average respiration rate. Carbon dioxide. Respiratory quotient. Oxygen. Average pulse rate. Heat (computed) . Without food : Av. of 3 periods. . . With food:1 10h29ma.m 12 15 c.c. 202 214 0.83 .80 c.c. 244 267 65 68 cola. 1.18 1.28 10 58 a.m 15 200 .76 263 65 1.25 11 31 a.m .... 16 212 .83 256 65 1.24 12 06 p.m . . . 14 214 .80 268 69 1.20 Subject drank coffee at 10h07m a. m. TABLE 87. — J. P. C.f March 27, 1911. Lying. (Values per minute.) Coffee (52° C.): Amount, 312 grams; nitrogen, 0.10 gram; total energy, 16 cals. Fuel value: Total, 16 cals.; from protein, 16 p. ct.; from carbohydrates, 84 p. ct. Time. Average respiration rate. Carbon dioxide. Respiratory quotient. Oxygen. Average pulse rate. Heat (computed). Without food: c.c. c.c. cala. Av. of 2 periods . . . 18 188 0.86 219 52 1.07 With food:1 12h10mp.m 20 191 .73 263 62 1 24 12 38 p.m 20 198 86 231 51 1 13 1 10 p.m 21 194 .81 240 63 1.16 1 45 p.m 20 199 .81 246 54 1.18 'Subject drank coffee at Ilh38m a. m. INGESTION OF COFFEE. 157 DISCUSSION OF RESULTS OF COFFEE EXPERIMENTS. As the coffee was taken hot in both of the calorimeter experiments, the same difficulties exist in making the proper correction for the changes in body-temperature that were indicated in the water-drinking experiments. With the subject A. H. M., in the calorimeter experi- ment of April 19, 1907, a positive increase in the heat production amounting to 11 per cent was noted. (See table 81.) Increments as great, if not greater, were shown in the carbon-dioxide production and oxygen consumption, thus confirming the fact that there was a true increase in the metabolism. In this case a relatively large amount of coffee, 1,011 grams, with 62 grams of sugar, was taken. That some of the increase in the metabolism may properly be ascribed to the sugar is clear from the data shown subsequently for the experiments in which the effect of ingesting cane sugar was studied. In the experiment with A. W. W. on April 12, 1907, the amount of coffee taken was much smaller, only 271 grams; in addition, 23 grams of sugar were given. According to the data in table 80, there was an actual lowering of the metabolism (3 per cent), with practically no change in either the carbon-dioxide production or the oxygen consump- tion. To a certain extent, then, this experiment is similar to the experi- ments with hot water in which no material effect was observed on the metabolism. In fact, neither of these two experiments can be taken as giving positive evidence of an increase in the metabolism due to the ingestion of coffee. The series of six respiration experiments with five subjects, all made in March 1911, gave more convincing results. (See tables 82 to 87.) In these experiments approximately 325 grams of coffee were taken with a temperature, so far as known, of 50° to 60° C. The increments averaged approximately 8 per cent, with a maximum of 13 per cent and a minimum of 2 per cent. These positive increments in the metabolism are distinctly at variance with the results of the calorimeter experi- ment with A.W.W., in which a slight decrease appeared. But the general trend is clear, and one may properly state that approximately 325 grams of coffee infusion at a temperature of about 60° C. will produce an increment in the metabolism of 8 to 9 per cent. A careful analysis of the detailed data for these experiments shows that in practically all instances the increment was by no means at an end at the conclusion of the experiment; thus these figures probably represent low rather than high values. For example, in the experiment with J. J. C. on March 9, 1911, a basal metabolism of 222 c.c. of oxygen consumed was recorded. Over 5 hours later, at the end of the experi- ment, the oxygen consumption was 268 c.c. A similar long-continued effect was noted with the same subject on March 21, 1911. It is thus clear that the ingestion of coffee produces a positive increment in the 158 FOOD INGESTION AND ENERGY TRANSFORMATIONS. metabolism which must not be neglected in the interpretation of exper- iments in which it has been taken. It is conceivable that in the earlier experiments with diabetics reported from this laboratory by Benedict and Joslin the small amount of coffee taken by the subject one or two hours before the experiment may have been responsible for a part of the increase noted in the metabolism, although it was at that time specifically stated that the coffee could have no influence.1 The amount of coffee taken by the diabetics was, however, less than half of the amount given in these experiments, and it was usually taken some time prior to the beginning of the observations. Since Novem- ber 1914, no coffee has been used by the diabetic subjects on the morning of the experiment. An examination of the pulse-rate data obtained in the coffee experi- ments shows slight increases after the ingestion of coffee for nearly all of the experiments, with usually a subsequent rapid fall to its previ- ous level. In one experiment, that with L. E. E., March 23, 1911, the rate was lower after the coffee was taken. The systolic blood pressure was higher in most instances after the coffee was drunk. The maximum rise was about 20 mm. mercury in the experiment with J. J. C. on March 9, 1911. Experiments made by Edsall and Means2 and Higgins and Means3 on the effect of caffein have an interest in this connection, as they show clearly the influence upon the metabolism of this constituent of coffee. Two experiments were made by Edsall and Means in the Massachusetts General Hospital, both of which indicated a definite although not very great rise in the metabolism. Those made by Higgins and Means, and published from this laboratory, show that with one of the subjects, J. H. M., the gaseous metabolism was markedly increased. With H. L. H. there was also an increase in the metabolism, although this was slight. We may conclude, therefore, that coffee, owing probably to its caffein content, acts as a stimulus to the metabolism, the increment with 325 grams of coffee infusion amounting on an average to 8 per cent for several hours. Experiments with caffein-free coffee would therefore have special interest. Benedict and Joslin, Carnegie Inst, Wash. Pub. No. 136, 1910, p. 216. "Edsall and Means, Arch. Intern. Med., 1914, 14, p. 897. 'Higgins and Means, Journ. Pharm. and Exp. Therapeutics, 1915, 7, p. 1. INGESTION OF BEEF TEA. 159 INGESTION OF BEEF TEA. The noticeable increase in metabolism found by the earlier investi- gators as a result of the ingestion of flesh led to tests on animals to determine the influence of extracts which consist chiefly of creatine and its allied compounds. Experiments with man on this subject are extremely limited in number. Beef extract (probably 15 per cent water) in amounts of 12 to 18 grams per day was used in some of the classical experiments of Pettenkofer and Voit1 on their so-called fasting days, but as no suitable basal value is available for comparison the results of the experiments give no evidence as to the possible effect of the extract upon the metabolism. In our study on the influence of the ingestion of food, a study was also made of the effect of ingesting beef tea. STATISTICS OF EXPERIMENTS. The series of experiments on beef tea included five experiments with the respiration calorimeter at Middletown (see tables 88 to 92) and two experiments with the chair calorimeter at Boston (see tables 93 and 94). In addition, six experiments were made with the uni- versal respiration apparatus in Boston (see tables 95 to 100). The results of these experiments are summarized in tables 67 and 68. (See pages 135 and 136.) For the calorimeter experiments the beef tea was made by extracting fresh beef with water; in all but one of the respiration experiments it was prepared from a so-called extract of beef, a commercial product being used. The composition of the beef tea is indicated in table 50. (See page 124.) The method of preparation from the fresh beef was as follows: The beef (from the top of the round) was freed so far as possible from all visible fat and connective tissue, then chopped and covered with cold water to extract the juices; finally both meat and liquid were heated slowly to about 80° C. For a few experiments it was heated only to 40° C. The liquid was carefully filtered to remove the solid material and then cooled. To prepare it for the experiment the solidi- fied fat was removed, and the remainder reheated to approximately 80° C. Salt was added to taste by the subject. It is obvious that beef tea, prepared from either the fresh meat or the extract, would contain considerable amounts of creatine and crea- tinine.2 In some instances the analyses showed a large proportion of nitrogen, particularly in the experiment of May 9, 1907, in which 6.82 Pettenkofer and Voit, Zeitschr. f. Biol., 1866, 2, p. 459. 2The amount of creatine and creatinine in the beef tea used in the Middletown experiments M-as determined through the kindness of Dr. Victor C. Myers, at that time assistant pathologist at the Connecticut Hospital for the Insane and at present director of the Laboratory of Pathological Chemistry in the New York Post-Graduate Medical School and Hospital. 160 FOOD INGESTION AND ENERGY TRANSFORMATIONS. grams of nitrogen were taken in 1,605 grams of beef tea. Thus the beef tea, particularly that made from the fresh beef, did not consist wholly of extractives, but in all probability it contained an appreciable amount of protein. Accordingly, we must also consider here the possibility of a true protein ingestion. In a few of the calorimeter experiments the beef tea was given to the subject cold, but usually it was taken hot; the temperature of the liquid is recorded for each experiment in the statistical tables, also in the summary tables. In the respiration experiments, much smaller amounts were given than in the calorimeter experiments and the tem- perature was usually between 50° and 60° C. The total increment in the metabolism was computed for the respiration experiments by the planimeter method as described in the section on the ingestion of coffee. (See page 151.) Statistical data not included in the tables or in the discussion are given in the following paragraphs for all of the experiments. In this and subsequent statistics, the times given include both basal and food periods if the basal values were determined immediately before the ingestion of the food. CALORIMETER EXPERIMENTS. E. H. B., 8h27m a. m. to 4*27m p. m., April 8, 1907. 72.9 kilograms.— Urinated 6h50ra a. m. and 4h27m p. m.; took enema about 7h15m a. m. More or less activity in first period in connection with receiving beef tea and dishes, as subject was obliged to go to food aperture several times. Very quiet in last part of first period and in second period, but not so quiet in fourth period. Reading greater part of time; occasionally drowsy. Drank 134 grams water in fourth period. Body-temperature: 36.57°, 36.50°, 36.57°, 36.61°, and 36.66° C. Pulse rate, 51; respiration rate, 18. Beef tea heated to about 80° C. in preparation. Creatinine in beef tea, 0.0121 gram in 100 c.c.; crea- tine,1 0.109 gram in 100 c.c. A. H. M., 8h44m a. m. to 4h44m p. m., April 29, 1907. 67.4 kilograms.— Urinated 6, 9h47m, 10h54m a. m., 2h53m and 5h20ra p. m. Somewhat restless in first and third periods; more quiet in second and fourth periods; much of time reading. Body-temperature : 36.70°, 36.51°, 36.38°, 36.22°, and 36.42° C. Pulse rate, 60; respiration rate, 20. A. W. W., 8h34m a. m. to 4h24m p. m., May 2, 1907. 58.4 kilograms.— Urinated 7h10ra, 9h40m, 10h32m a. m., 12h28m, 2h32m, and 4h35m p. m. Felt cold after taking both portions of beef tea. Considerable activity in tele- phoning and getting beef tea from food aperture, but after 9h06m a. m. subject sat quietly and read ; very quiet in other periods. Drank water at beginning of fourth period (30 grams). Body-temperature: 36.41°, 36.60°, 36.64°, 36.76°, and 36.75° C. Pulse rate, 61; respiration rate, 20. Creatinine in beef tea, 0.011 gram in 100 c.c.; creatine,1 0.161 gram in 100 c.c. A. W. W., 8h25m a. m. to 4h25m p. m., May 9, 1907. 58.8 kilograms.- Urinated 7h10ra a. m. (after enema), 12h32m and 4h34m p. m. Very quiet in first period after 9 o'clock, also in second and fourth periods; in third period, somewhat more active. Perspired very freely for a short time after drinking beef tea. Drank water at beginning of both second and third periods (216 'Expressed as creatinine. INGESTION OF BEEF TEA. 161 grams). Body-temperature: 36.62°, 36.75°, and 36.88° C. Pulse rate, 62; respiration rate, 21. Beef tea used was of double strength and not heated above 40° C. in making. Coagulated somewhat when reheated to about 75° C. before serving. Creatinine in beef tea, 0.018 gram in 100 c.c.; crea- tine,1 0.211 gram in 100 c.c. A. H. M., 8h24m a. m. to 4h%4m p. m., May 10, 1907. 66.7 kilograms.— Beef tea used for this experiment same as that used for A. W. W., May 9, 1907, but not heated to so high a temperature for serving; no coagulation. Subject urinated 7, 10h28m a. m., 12h36m and 4h32ra p. m. Very quiet, read greater part of time. Telephoned and opened food aperture at 8h32m a. m. Body-temperature: 36.62°, 36.51°, 36.49°, 36.74°, and 36.68° C. Pulse rate, 59; respiration rate, 18. J. J. C., 9h02m a. m. to Sh49m p. m., May 12, 1910. 64.7 kilograms.— Urinated at 6h55ra, 9hllm, Ilh04m, Ilh53m a. m. and Ih15m p. m. Slept con- siderable part of experiment; slept 10 minutes in first basal period, 10 minutes in second period, and about half of first period after beef tea. Awakened by observer and to prevent his falling asleep again was told to ring telephone bell every 5 minutes as evidence of being awake. Fell asleep at Ih12m p. m. (in third period after beef tea), also at 3h44m p. m. (in fifth period). Moved considerably at Ih43m p. m. Basal periods: body-temperature, 36.81°, 36.57°, 36.58° C.; pulse rate, 64; respiration rate, 19. Periods after beef tea: body-temperature, 36.85°, 36.81°, 36.85°, 36.79°, and 36.71° C.; pulse rate, 65; respiration rate, 20. Both pulse and respiration records are lacking for a part of the experiment. J. K., 8h57m a. m. to 3h32m p. m., May 13, 1910. 69.5 kilograms.— Took enema before entering apparatus. During basal periods telephoned once; at end of second period complained of pain in stomach. After taking beef tea, had nausea and drank water (28 grams). During periods after beef tea did not feel well; was restless, telephoned several times, drank water (37 grams) in first period, urinated in second period and again at 3h40m p. m. (after experi- ment). Basal periods: pulse rate, 65; respiration rate, 15. Periods after beef tea: pulse rate, 68; respiration rate, 16. TABLE 88. — E. H. B., April 8, 1907. Sitting. (2-hour periods.) Beef ten (8S.5° C.) : Amount, 892 grams; nitrogen, 1.61 grams; total energy, 71 cala. Fuel value: Total, 57 cals.; from protein, 72 p. ct.; from fat, 15 p. ct.; from car- bohydrates, 13 p. ct. Nitrogen in urine, 0.72 gram per 2 hours.1 Batal values (March 7 and 13, 1907): COj, 58 grams; O2, 48 grams; heat, 179 cals. Time elapsed Carbon dioxide. Oxygen. Heat. since subject finished eating. Total. Increase. Total. Increase. Total. Increase. grama. grama. grams. grams. cals. call. 0 to 2 hours3 . . 63 5 56 8 182 3 2 to 4 hours. . . 57 -1 47 -1 182 3 4 to 6 hours. . . 56 -2 49 1 171 -8 6 to 8 hours. . . 56 — 2 48 0 170 -9 Total . . . 232 0 200 8 705 -11 1Expressed as creatinine. ^Sample included amount for about if hours, without food, preceding experiment. 'Subject drank beef tea in 17 minutes, finishing 25 minutes after the beginning of this period. 162 FOOD INGESTION AND ENERGY TRANSFORMATIONS. TABLE 89. — A. H. M., April 29, 1907. Sitting. (2-hour periods.) Beef tea (22° C.) : Amount, 1,143 grams; nitrogen, 2.78 grams; total energy, 116 cals. Fuel value: Total, 91 cals.; from protein, 79 p. ct.; from fat, lip. ct.; from carbohy- drates, 10 p. ct. Basal values (March 6 and 9, 1907): COz, 51 grams; Oz, 46 grams; heat, 164 cals. Nitro- gen in urine, 1.06 grams per 2 hours (April 29, 1907). Time elapsed Nitrogen Carbon dioxide. Oxygen. Heat. since subject in urine finished per eating. 2 hours. Total. Increase. Total. Increase. Total. Increase. grams. grams. grams. grams. grams. cals. cals. 0 to 2 hours1. . 1.542 62 11 51 5 182 18 2 to 4 hours . . 1.11 54 3 50 4 165 1 4 to 6 hours. . 1.11 51 0 46 0 158 -6 6 to 8 hours . . .93 52 1 44 -2 164 0 Total... 219 15 191 7 669 13 Subject finished drinking beef tea 14 minutes after the beginning of this period. The drink- ing occupied 12 minutes. 'Computed from amount for 67 minutes in latter portion of period. TABLE 90.— A. W. W., May 2, 1907. Sitting. (2-hour periods.) Beef tea (1,413 grams, 22° C.; 643 grams, 7° C.) : Amount, 2,056 grams; nitrogen, 4.27 grams; total energy, 185 cals. Fuel value: Total, 148 cals.; from protein, 75 p. ct. ; from fat, 13 p. ct. ; from carbohy- drates, 12 p. ct. Basal values (March 15 and 21, 1907): CC>2, 50 grams; Oa, 41 grams; heat, 155 cala. Nitrogen in urine, 0.81 gram per 2 hours (May 2, 1907). Time elapsed Nitrogen Carbon dioxide. Oxygen. Heat. since subject in urine finished per eating. 2 hours. Total. Increase. Total. Increase. Total. Increase. grams. grams. grams. grams. grams. cals. cals. 0 to 2 hours1. . 1.042 62 12 53 12 191 36 2 to 4 hours . . 0.17 52 2 36 -5 136 -19 4 to 6 hours. . 1.35 50 0 43 2 150 -5 6 to 8 hours . . 1.17 50 0 40 -1 147 -8 Total . . . .... 214 14 172 8 624 4 'Subject finished drinking beef tea 38 minutes after the beginning of this period. The drink- ing occupied 15 minutes. 'Computed from amount for 52 minutes in latter portion of period. INGESTION OF BEEF TEA. 163 TABLE 91.— A. W. W., May 9, 1907. Sitting. (2-hour periods.) Beef tea (54° C.) : Amount, 1,605 grams; nitrogen, 6.82 grams; total energy, 264 cals. Fuel value: Total, 204 cals.; from protein, 86 p. ct.; from fat, 7 p. ct.; from carbohy- drates. 7 p. ct. Basal values (March 15 and 21, 1907): CO2, 50 grams; Oj, 41 grams; heat, 155 cals. Time elapsed Nitrogen Carbon dioxide. Oxygen. Heat.1 since subject in urine finished per eating. 2 hours. Total. Increase. Total. Increase. Total. Increase. grams. grams. grams. grams. grams. cals. cals. 0 to 2 hours2. . 1.363 63 13 51 10 170 15 2 to 4 hours . . 1.363 59 9 43 2 169 14 4 to 6 hours . . 1.18 63 3 36 -5 151 -4 6 to 8 hours . . 1.18 51 1 43 2 152 -3 Total . . . 226 26 173 9 642 22 lHeat eliminated corrected for change in body-weight, but not for change in body -temperature. •Subject finished drinking beef tea 33 minutes after beginning of this period. The drinking occupied 18 minutes. •Sample included amount for l£ hours, without food, preceding experiment. TABLE 92.— A. H. M., May 10, 1907. Sitting. (2-hour periods.) Beef tea (50° C.) : Amount, 892 grams; nitrogen, 3.79 grams; total energy, 147 cals. Fuel value: Total, 113 cals.; from protein, 86 p. ct.; from fat, 7 p. ct.; from carbohy- drates, 7 p. ct. Basal values (March 6 and 9, 1907): COz, 51 grams; (>2, 46 grams; heat (computed), 152 cals. i Time elapsed Nitrogen Carbon dioxide. Oxygen. Heat (computed.) since subject in urine finished per eating. 2 hours. Total. Increase. Total. Increase. Total. Increase. grams. grams. grams. grams. grams. cals. calt. 0 to 2 hours1. . 1.622 65 14 54 8 182 30 2 to 4 hours . . 1.59 53 2 42 -4 141 -11 4 to 6 hours . . 1.19 54 3 50 4 165 13 6 to 8 hours . . 1.19 52 1 41 -5 140 -12 Total . . . 224 20 187 3 628 20 'Subject finished drinking beef tea 20 minutes after the beginning of this period. The drinking occupied 8 minutes. 'Sample included amount for about 1} hours, without food, preceding experiment. 164 FOOD INGESTION AND ENERGY TRANSFORMATIONS. TABLE 93.— J. J. C., May 12, 1910. Sitting. (1-hour periods.) Beef tea (932 grams, 15.5° C. ; 290 grams, 38° C.) : Amount, 1,222 grams; nitrogen, 5.62 grams; total energy, 214 cals. Fuel value: Total, 165 cals.; from protein, 87 p. ct. ; from fat, 7 p. ct. ; from carbohy- drates, 6 p. ct. Nitrogen in urine, 1.03 grams per hour (in first two periods).1 Basal values (May 12, 1910): CO2, 25 grams; Oj, 20 grams; heat,3 79 cals.; respiratory quotient, 0.92. Nitrogen in urine, 0.34 gram per hour. Time elapsed since subject finished eating. Carbon dioxide. Oxygen. Heat." Respiratory quotient. Total. Increase. Total. Increase. Total. Increase. J to 1 J hours grams. 30.5 28.5 27.5 25.0 grams. 5.5 3.5 2.5 0.0 grams. 25.0 25.5 23.5 22.5 grams. 5.0 5.5 3.5 2.5 cals. 79 84 76 76 cals. 0 5 -3 -3 0.90 .82 .85 .80 1 J to 2 j hours 2} to 3i hours 3i to 4J hours Total 111.5 11.5 96.5 16.5 315 -1 .... 'Sample obtained previous to these periods, but also following the ingestion of beef tea, con- tained 0.85 gram nitrogen per hour. *Heat eliminated corrected for change in body- weight, but not for change in body- temperature. TABLE 94.— J. R., May 13, 1910. Sitting. (1-hour periods.) Beef tea (44.1° C.) : Amount, 314 grams; nitrogen, 1.26 grams; total energy, 48 cals. Fuel value: Total, 37 cals.; from protein, 86 p. ct.; from fat, 7 p. ct. ; from carbohydrate!, - 7 p. ct. Basal values: CO-,, 26 grams (May 13, 1910); O2, 22.5 grams (March 21 to May 13, 1910); heat,1 80 cals. (May 13, 1910). Time elapsed since subject finished Nitrogen in urine Carbon dioxide. Oxygen. Heat.1 Respira- tory eating. per hour. Total. Increase. Total. Increase. Total. Increase. quotient. gram. grams. grams. grams. grains. cals. cals. i to 1 J hours . 0.532 29.0 3.0 24.0 1.5 81 1 0.87 1 J to 2} hours. .59 26.5 .5 24.5 2.0 78 -2 .79 2 J to 3 J hours . .59 26.0 .0 23.0 0.5 76 -4 .81 3 i to 4 J hours . .59 26.0 .0 24.0 1.5 77 _g .78 Total 107.5 3.5 95.5 5 . 5 312 -8 'Heat eliminated corrected for change in body-weight, but not for change in body- temperature. 'Sample included amount for 3J hours, without food, preceding drinking of beef tea. INGESTION OF BEEF TEA. 165 RESPIRATION EXPERIMENTS. J. J. C., 8h59m a. m. to 3h40m p. m., January 25, 1911. 64.3 kilograms.- Was awake throughout first basal period, but very sleepy and quiet; slept about half of second period, and asleep part of third period. In periods after beef tea, slept part of first and second periods, awake throughout third period, slept much of time in fourth period in spite of efforts to keep him awake; coughed once and jumped at a sudden noise in the room; awake in fifth and sixth periods, sleepy in seventh period, and slept between seventh and eighth periods; awake in eighth and ninth periods and very quiet. Nitrogen in urine per hour 7 a. m. to 3h40m p. m., 0.50 gram. V. G., 8*41™ a. m. to 4*51m p. m., January 26, 1911. 55.0 kilograms.— Awake and quiet in first basal period, sleepy in second, very sleepy in third period ; was awakened several times and did not sleep more than 2 minutes at any time. After beef tea, awake in all periods and for most part quiet ; very quiet in seventh period after beef tea; coughed twice in first period, twice in second period; slight leak in nosepieces in eighth period. Nitrogen in urine per hour 7h45m a, m. to 4h55m p. m., 0.39 gram. C. H. H., 9 a. m. to 4h42m p. m., January 27, 1911. 55.2 kilograms.— Had walked 1.25 miles since 5 p. m. the day before (pedometer record). Awake and quiet both basal periods and periods after beef tea. A desire to urinate in eighth period after beef tea, but no discomfort. Blood pressure : basal peri- ods, 107, 109, 113 mm.; periods after beef tea, 106, 101, 96, 98, 101, 113, 114, 115, 107 mm. Nitrogen in urine per hour 7h20m a. m. to 4h55m p. m., 0.45 gram. C. H. //., 9 a. m. to 4h45m P- ni., February 2, 1911. 54.5 kilograms.— Between 5h15m p. m., February 1, and 8 a. m., February 2, subject walked 3.6 miles (pedometer record) ; amount of activity probably greater, as subject skated 2 hours during evening preceding experiment. Awake and very quiet throughout basal and food periods. Blood pressure: basal periods, 107, 106, 105mm.; periods after beef tea, 120, 112, 106, 105, 114, 114, 112, 112, 112mm. Nitrogen in urine per hour 8h15ra a. m. to 4h55m p. m., 0.40 gram. V. G., 8*45m a. m. to 5h01m p. m., February 3, 1911. 54.8 kilograms. — Walked 3.9 miles between 5 p. m. February 2 and 8 a. m. February 3 (pedometer record). Awake and very quiet in first basal period, fell asleep once or twice in second period, but was immediately wakened. Beef tea produced nausea; subject unable to drink all provided. After beef tea, awake and quiet in first period, slept in second period a little; impossible to keep him awake continuously in third period, even with frequent ringing of an electric bell; in this period moved slightly in sleep and pneumograph slipped out of position. In fourth period, slept very little, if any, and was awake and quiet in fifth and sixth periods; fell asleep again for 3 or 4 minutes in seventh period. In four last periods awake and quiet for most part, but slept some in ninth period. Blood pressure: basal periods, 93, 96 mm.; periods after beef tea, 93, 100, 99, 104, 102, 105, 94, 99, 93, 100, 97 mm. Nitrogen in urine per hour 7h45m a, m. to 5h12m p. m., 0.31 gram. C. H. H., 9h03m a. m. to 4h55m p. m., February 8, 1911. 55.1 kilograms.- Very quiet and awake throughout basal and food periods. Fourth period was shortened to 11 minutes owing to slipping of nosepieces, which caused a leak. Blood pressure: basal periods, 107, 97, 95 mm.; periods after beef tea, 100, 104, 111, 111, 107, 106, 108, 107 mm. Nitrogen in urine per hour 8h15m a. m. to 5h12m p. m., 0.49 gram. 166 FOOD INGESTION AND ENERGY TRANSFORMATIONS. TABLE 95. — J. J. C., January 25, 1911. Lying. (Values per minute.) Beef tea (53° to 50° C.) : Amount, 400 grams; nitrogen, 1.56 grams; total energy, 61 cals. Fuel value: Total, 47 cals.; from protein, 85 p. ct. ; from fat, 8 p. ct.; from carbohydrates, 7 p. ct. Time. Average respiration rate. Carbon dioxide. Respiratory quotient. Oxygen. Average pulse rate. Heat (computed) . Without food: Av. of 3 periods . . . With food:1 10h51ma.m 17 21 c.c. 196 222 0.86 90 c.c. 229 248 64 73 cals. 1.12 1 22 11 16 a.m 18 226 88 257 67 1 26 11 42 a.m 21 227 95 240 72 1 20 12 13 p.m . 19 227 86 263 71 1 28 12 38 p.m 20 220 79 278 68 i ^n 1 04 p.m 21 220 86 256 68 i i*\ 1 30 p.m 19 214 84 254 68 1 2^ 2 33 p.m 22 219 .82 267 72 1 29 2 58 p.m 22 215 84 256 77 1 24 3 25 p.m. . 22 217 79 274 77 1 31 'Subject drank beef tea at 10h43m a. m. TABLE 96. — V. G., January 26, 1911. Lying. (Values per minute.) Beef tea (55.2° to 53.6° C.) : Amount, 400 grams; nitrogen, 1.45 grams; total energy, 57 cals. Fuel value: Total, 44 cals.; from protein, 84 p. ct. ; from fat, 8 p. ct.; from carbohydrates, 8 p. ct. Time. Average respiration rate. Carbon dioxide. Respiratory quotient. Oxygen. Average pulse rate. Heat (computed) . Without food : Av. of 3 periods. . . With food:1 10h42ma.m 20 19 c.c. 188 202 0.84 .84 c.c. 225 241 63 67 cals. 1.09 1 17 11 15 a.m 21 213 .90 237 65 1 17 11 46 a.m 20 196 .87 226 61 1 10 12 18 p.m 20 190 .82 231 58 1 11 12 48 p.m 20 214 .87 247 62 1 21 1 23 p.m . . 20 213 .86 248 60 1 21 2 29 p.m 18 202 .84 240 58 1 16 3 25 p.m 19 206 .83 249 59 1 20 4 36 p.m 20 209 .82 255 60 1 23 Subject drank beef tea between 10h21m and 10h26m a. m. INGESTION OF BEEF TEA. 167 TABLE 97.— ('. //. H., January 27, 1911. Lying. (Values per minute.) Beef tea (52.8° to 52.0° C.) : Amount, 400 grams; nitrogen, 1.44 grams; total energy, 57 cals. Fuel value: Total, 44 cals.; from protein, 84 p. ct. ; from fat, 8 p. ct.; from carbohydrates, 8 p. ct. Time. Average respiration rate. Carbon dioxide. Respiratory quotient. Oxygen. Average pulse rate. Heat (computed). Without food: Av. of 3 periods . . . With food:1 10h55ma.m 15 15 c.c. 174 180 0.84 .84 c.c. 206 214 61 62 cals. 1.00 1 04 11 26 a.m 15 186 62 1 05 11 54 a.m 15 184 .88 210 62 1 03 12 27 p.m . 14 182 85 214 59 1 04 12 56 p.m 14 173 .81 214 58 1 03 2 18 p.m 14 188 85 220 61 1 07 2 58 p.m 14 172 81 212 60 1 02 3 52 p.m. 14 183 82 224 62 1 08 4 27 p.m 15 180 85 212 61 1 03 'Subject drank beef tea between 10u46ra and 10h50m a. m. TABLE 98. — C. H. H., February 2, 1911. Lying. (Values per minute.) Beef tea (614° to 59.0° C.) : Amount, 400 grams; nitrogen, 1.46 grams; total energy, 57 cals. Fuel value: Total, 44 cals.; from protein, 84 p. ct. ; from fat, 8 p. ct. ; from carbohydrates, 8 p. ct. Time. Average respiration rate. Carbon dioxide. Respiratory quotient. Oxygen. Average pulse rate. Heat (computed). Without food: Av. of 3 periods . . . With food:1 10h48ma.m 15 15 c.c. 169 164 0.82 .76 c.c. 206 215 65 69 cals. 0.99 1 02 11 14 a.m 14 180 80 225 68 1 08 11 53 a.m 16 186 .85 218 68 1 06 12 25 p.m 16 177 .78 227 67 1 08 1 12 p.m 15 176 .77 228 65 1 09 2 03 p.m . . . 15 170 .79 214 66 1 02 2 52 p.m. 15 164 .76 215 65 1 02 4 04 p.m 15 172 .80 214 64 1 03 4 30 p.m 16 173 78 223 64 1 07 'Subject drank beef tea between 10h36m and 10h40m a. m. 168 FOOD INGESTION AND ENERGY TRANSFORMATIONS. TABLE 99. — V. G., February 3, 1911. Lying. (Values per minute.) Beef tea (68.7° to 60.0° C.) : Amount, 269 grams; nitrogen, 0.98 gram; total energy, 38 cals. Fuel value: Total, 30 cals.; from protein, 84 p. ct. ; from fat, 9 p. ct. ; from carbohydrates, 7 p. ct. Time. Average respiration rate. Carbon dioxide. Respiratory quotient. Oxygen. Average pulse rate. Heat (computed). Without food: Av. of 2 periods. . . With food:1 10h24ma.m 19 19 c.c. 178 181 0.79 .78 c.c. 224 233 58 61 call. 1.07 1.11 10 52 a.m 20 193 .79 245 63 1 17 11 29 a.m 19 195 83 235 59 1 14 12 02 p.m 19 195 80 244 60 1 17 12 36 p.m 18 195 .80 244 59 1 17 1 05 p.m 19 202 .80 254 63 1 22 1 53 p.m . 19 193 78 247 61 1 18 2 33 p.m 19 198 .80 247 60 1.19 3 09 p.m 21 185 .74 249 59 1.18 4 21 p.m 20 205 .82 250 63 1.21 4 46 p.m 20 206 .81 254 62 1 22 Subject drank beef tea between 10h10m and 10h13m a. m. TABLE 100. — C. H. H., February 8, 1911. Lying. (Values per minute.) Beef tea (664° to 60.0° C.) : Amount, 350 grams; nitrogen, 4.30 grams; total energy, 64 cals. Fuel value: Total, 41 cals.; from protein, 84 p. ct.; from fat, 9 p. ct.; from carbohydrate! , 7 p. ct. Time. Average respiration rate. Carbon dioxide. Respiratory quotient. Oxygen. Average pulse rate. Heat (computed). Without food: Av. of 3 periods . . . With food :' 12b08mp.m 14 14 c.c. 173 179 0.82 .85 c.c. 210 210 65 68 rait. 1.01 1 02 12 36 p.m . . . . 14 187 83 224 71 1.08 1 08 p.m 14 195 86 228 70 1 11 1 39 p.m . 16 194 70 1 07 2 13 p.m 14 192 91 212 69 1 05 2 49 p.m 3 28 p.m 4 40 p.m . . 14 15 14 191 179 182 .87 .81 82 219 222 221 68 66 70 1.07 1.07 1 07 'Subject drank beef tea between Ilh54m and 12 a. m. INGESTION OF BEEF TEA. 169 DISCUSSION OF RESULTS OF BEEF-TEA EXPERIMENTS. An examination of the summary of values given for the calorimeter experiments in table 67 (see page 135) shows that there was but little or no increase in the heat output in these experiments. The maxi- mum increment was that on May 9, 1907, of 4 per cent. Furthermore, the figures show no variation as a result of the differences in the tem- perature of the beef tea, nor is there an apparent correlation between the total nitrogen content of the beef tea and the heat increment. The beef tea for the respiration experiments, the results of which are summarized in table 68, was made from beef extract in all cases except for the experiment with C. H. H. on February 8, 1911. In prac- tically every experiment there was a perceptible increase in the metab- olism, the maximum being that in the experiment with J. J. C., on January 25, 1911, namely, 12 per cent. The average increment was not far from 8 per cent, a result strikingly at variance with that found in the calorimeter experiments. This is all the more significant as comparatively small amounts were given in the respiration experiments (never more than 400 grams), while in the calorimeter experiments, if we exclude that with J. R., the amount ingested ranged from 892 grams to 2,056 grams. As further evidence of the positive increase noted in the respiration experiments, an examination of the detailed results given in tables 95 to 100 shows that the increment in the oxygen consumption was usually still present at the end of the experiment, i. e., the metabolism had not reached the basal level. The values for the total increment here recorded are therefore for the most part smaller than would have been obtained had the experiment been continued. The most striking result obtained in these experiments is the very small reaction to the beef tea shown by the subject C. H. H., this being much less than in any of the other respiration experiments in the series. This man was a particularly satisfactory subject with the respiration apparatus, as he lay without movement for hours at a time and showed an unusually clear understanding of the requirements of a cooperating subject. The high values obtained with J. J. C. and V. G. can probably be ascribed to their tendency towards restlessness and lack of cooperation. In any event the results of these respiration experi- ments appear to show that beef tea, when prepared from the so-called commercial extract of beef, has an influence on the metabolism. This effect in certain of the experiments was fairly long continued and amounted at times to an increase of heat approximately 8 to 10 per cent above the basal value. The pulse rate was affected to a slight extent in the calorimeter experiments in Boston. Only two of the experiments with the respira- tion apparatus show significant increases in pulse rate, these being the experiment with C. H. H.. February 8, 1911, in which the rate rose 170 FOOD INGESTION AND ENERGY TRANSFORMATIONS. from 65 per minute to a maximum of 71, and the experiment with V. G., January 26, 1911, in which the pulse rate changed from an average of 53 per minute to 67 to 60 per minute after the beef extract was taken. The systolic blood pressure was measured in the experiment with V. G., February 3, 1911, and in the three experiments with C. H. H. In none of them was there a marked change in the blood pressure. While beef extract has an effect upon the metabolism, its influence is so small that moderate amounts may be given to individuals in a fasting condition without materially increasing the basal value. Since it is highly desirable to secure a diet which will not materially raise the basal metabolism and yet will prevent the sensations of hunger fre- quently experienced by patients when the breakfast is omitted, it may be perfectly legitimate to use a moderate amount of beef extract in experiments with pathological cases even when determining the so- called basal value prior to observations. Special tests on this point should be made before beef extract is used in this way. In considering the influence of beef tea and other liquids upon the metabolism, the results obtained in the experiments on water-drinking should naturally be taken into consideration. A careful analysis of these experiments shows that the drinking of water was, in all but two instances, without effect upon the metabolism. On the other hand, the fact that increments were obtained in these two experiments, one of which — an extremely well-conducted and satisfactory experiment — showed an increment of 16 per cent in the metabolism after 1,800 grams of water,1 must lead one to be somewhat cautious in the inter- pretation of results of experiments in which liquids are ingested. But the experimental data thus far obtained for beef tea may properly lead to the conclusion that with amounts of 400 grams or more a perceptible increase in the metabolism may be expected. 'See experiment with T. M. C. on January 12, 1911 (table 72, p. 144.) INGESTION OF CARBOHYDRATES. 171 INGESTION OF CARBOHYDRATES. In the historical development of the study on the influence of food upon the metabolism the first observations in which demonstrable increases could be determined were those with protein. These in- creases were so large that it was not at all strange that observers expected to find a considerable rise in the metabolism with both fat and carbohydrates. Accordingly, when a much smaller increment in the metabolism was found with carbohydrates than that obtained in experiments with protein, the influence of the former class of nutrients was without doubt given less consideration than it should have been. The actual importance of the increases with carbohydrates may have been obscured by several causes. First, the effect of carbohydrate ingestion persists for a much shorter time than that following the inges- tion of protein; hence, in the experimental period first used (24 hours) the increase in the metabolism in the hours immediately following the taking of the carbohydrate food may have disappeared when the values for the essentially basal metabolism in the later hours of the day were included; in other words, the "peak" effect of the carbohydrate inges- tion was lost as a result of the lengthening of the experimental period. Secondly, it has frequently happened that the basal value was deter- mined in 24 hours, or even longer, of complete starvation. Experi- ments have shown1 that during a period of this length without food there is a very considerable draft upon the carbohydrate storage in the body; consequently when carbohydrate is afterwards ingested, the body attempts first to replenish the store of this material. The effect on the metabolism due to the ingestion of food is thus considerably less- ened by the fact that the carbohydrate is in large part not burned, but simply stored as glycogen. In Rubner's experiment on man2 (and in this monograph we are dealing entirely with experiments on man) a series of experiments on 5 consecutive days was carried out. On the first day the subject fasted and did no work ; on the second day he was given protein without work ; on the third day protein with work; on the fourth day sugar without work ; and on the fifth day sugar with work. Considering specifically the fourth day, when sugar was given without work, we find that the heat output per 24 hours was 2,023 calories as compared with a basal value of 1,976 calories, an increment of only 47 calories. A close exam- ination of the experimental procedure shows that the 3 days prior to the sugar day, i. e., a day of hunger, a day with protein, and a day with protein and work, all contributed toward the depletion of the glycogen supply in the body, and it is not surprising that no larger increment in the metabolism was found. 'Johansson, Skand. Arch. f. Physiol., 1909, 21, p. 1. See, also, p. 70 of this monograph. 'Rubner, Sitzber. K. Preuss. Akad. Wiss., 1910, p. 316. 172 FOOD INGESTION AND ENERGY TRANSFORMATIONS. It is surprising, however, that according to the method of com- puting the energy used by Rubner at that time, it was assumed that the carbohydrates were first burned. As the 600 grams of cane sugar given on that day correspond to an energy consumption of approxi- mately 2,400 calories, or more than was actually measured, it is pre- sumable that the 2, 023 calories given by Rubner as the value for the heat output is based upon the assumption that the combustion for the day was entirely of pure carbohydrate. This amount of energy would be produced by the combustion of approximately 510 grams of sugar. It is well known that 50 to 100 or more grams of glycogen may be with- drawn on the first day of fasting. It is quite likely, therefore, that an appreciable portion of the sugar ingested may have been used to form glycogen and not to contribute to the increased metabolism measured by Rubner. Rubner's calculations are seriously hampered by the absence of data regarding the oxygen consumption, which would contribute more directly to the computation of the total energy transformations. The increment in the carbon-dioxide production has been more employed for such researches as these than any other factor. Even when used in special studies like those of Johansson and Gigon,1 an attempt to explain the processes on the basis of this increment immediately results in great confusion. A typical case will serve to illustrate this. If a subject has been without food for 12 hours or more and is drawing upon body material to the extent of 15 per cent of the total energy in the form of protein and the other 85 per cent is apportioned between carbohydrate and fat, presumably in the proportion of 45 per cent of carbohydrate and 40 per cent of fat, the respiratory quotient will be approximately 0.85. When carbohydrate is ingested there is immediately a great rise in the respiratory quotient and an increase in the production of carbon dioxide. It may be argued, then, in common with the old conception of von Hoesslin,2 that a fat-carbohydrate- protein combustion is replaced by an exclusively protein-carbohydrate combustion, without altering in any way the total amount of energy transformed. This is one possibility. Another possibility is that there may be a transformation of carbo- hydrate into fat. By this process, which has been definitely proved in several laboratories in a number of ways, there may be a formation of 'Probably no research on the influence of the ingestion of pure carbohydrate has been more accurately and carefully carried out than that of Johansson at Stockholm (see pp. 34 and 35), which was supplemented by the subsequent experiments of Johansson's former assistant, Gigon (see p. 38) . While Rubner's criticism (Die Gesetze des Energieverbrauchs bei der Ernahrung, 1902, p. 216) of Johansson's method of computing the carbon-dioxide production of a single individual in half- hour periods seems justified when we consider that the volume of air in the chamber was 100,000 liters, nevertheless personal visits to Stockholm have convinced us that the remarkable Sonden gas-analysis apparatus used by Johansson permits measurements of carbon dioxide with a suffi- cient degree of accuracy to justify recording values for half-hour periods with this chamber, if not, indeed, for 15-minute periods. *von Hoesslin, Arch. f. path. Anat. u. Physiol., 1882, 89, p. 341. INGESTION OF CARBOHYDRATES. 173 fat and a splitting off of carbohydrate when large amounts of carbo- hydrate are ingested, with a so-called "atypical" carbon-dioxide produc- tion, unaccompanied by an increase in the oxygen consumption. In other words, this process is entirely aside from the katabolic processes in the body and does not affect the total katabolism appreciably, though there is a slight energy output incidental to the transformation. Finally, there may be an actual increase in the total katabolism, which would of itself result in an increased carbon-dioxide production. This increase in the katabolism may be caused by an increased tonus and an increased activity in the digestive tract due to the stimulating effect of the absorbed food materials upon the body cells. It is thus clear that these three processes, which may take place simultaneously in varying degrees of intensity, greatly complicate the interpretation of results based only upon the carbon-dioxide increment. The experiments in this research which were designed to study the influence of the ingestion of carbohydrates were planned to measure not only a prolonged effect but particularly to show the maximum carbon-dioxide production and oxygen consumption which might appear early in the observations. In the calorimeter experiments measurements were also made of the heat production. For the respiration experiments the heat production was calculated from the results obtained for the gaseous exchange. A number of carbohydrate food materials were used, including not only pure carbohydrates, such as cane sugar, dextrose, levulose, and milk sugar, but also those of a mixed nature, like bananas and popcorn. As in the series of experi- ments already discussed, the data were secured with the respiration calorimeter at Wesleyan University, Middletown, and with the chair calorimeter and two forms of respiration apparatus at the Nutrition Laboratory, Boston. CALORIMETER EXPERIMENTS. The agreement between the results obtained by direct and indirect calorimetry in the calorimeter experiments was, in many instances, extremely unsatisfactory, so much so that for a long time we were dis- posed to question the value of our calorimeter measurements, par- ticularly those with the Boston calorimeters. Subsequent experi- mentation has shown, however, that direct and indirect calorimetry may not necessarily agree under the abnormal conditions previously outlined which obtain when excessive amounts of carbohydrates are ingested. To secure a satisfactory agreement between direct and indirect calorimetry is a problem that has received a great deal of attention ever since the earliest days of direct measurements of the heat output of man. The attempt was made in all of our experiments to determine 174 FOOD INGBSTION AND ENERGY TRANSFORMATIONS. the heat output directly with as high a degree of accuracy as possible. The respiration calorimeter at Middletown was designed primarily for 24-hour periods. On this basis the agreement between direct and indirect calorimetry has almost invariably proved satisfactory, especially after the apparatus was modified to permit the direct measurement of the oxygen consumption. Previous to the beginning of this research on the influence of food upon the metabolism, no attempt was made to compare direct and indirect calorimetry in periods shorter than 24 hours. When such an attempt was made, it was found that at least with the Middletown calorimeter, which had an air con- tent of approximately 5,000 liters, great difficulty was experienced in the measurement of the residual air and particularly of the residual oxygen, and the possibility of experimental error was thus increased as the periods were decreased in length. Direct measurements of the heat production are also complicated by the difficulty in obtaining accurate measurements of the rectal temperature. Furthermore, the ingestion of large masses of food at a temperature above or below that of the body increases the difficulty, as the length of time required to bring the ingested food and the stomach wall to the temperature of the body is a matter of considerable speculation. Still, the general coinci- dence of the results obtained with both direct and indirect calorimetry lends credence to any deduction drawn from either. It should be said, further, that the researches conducted under the skillful guidance of Dr. E. F. Du Bois, at the Russell Sage Institute of Pathology in New York, have definitely demonstrated the fact that accurate comparisons of the direct and indirect calorimetry can be secured, even in periods as short as one hour. Such values for the heat production as were obtained in this research by the indirect method were not computed with the idea of establishing a comparison between the direct and indirect heat values, but simply to obtain a general picture of the course of the metabolism after the ingestion of food. If both the direct and the indirect calorimetry show an increment in the metabolism, there is every reason to believe that such an increment actually took place. While the results obtained with the two methods by no means always agree closely, they yet sup- ply a rough confirmation of each other. As a rule, the tabulated values for the heat production in the calorimeter experiments are those obtained by direct measurement. In one case both sets of figures are given for illustration (see table 101, page 179). Unless otherwise stated, the values for the heat measurements are for the heat actually pro- duced— that is, the measured heat elimination corrected, in accord- ance with the usage of this laboratory,1 for changes in body-weight and body-temperature. Benedict and Joslin, Carnegie Inst. Wash. Pub. No. 136, 1910, p. 20. INGESTION OF CARBOHYDRATES. 175 Since it is the custom of many writers to compute the non-protein respiratory quotient and determine the non-protein metabolism in experiments of this kind, values for the nitrogen excretion in the urine have been given whenever obtainable, but with no idea of indicating the influence of the ingested food. Although basal values for nitrogen have been included in the tables whenever available, no effort was made to obtain such data for our experiments. In this we find ourselves at variance with Gigon, who assumed that the basal value for nitrogen was constant. It should be emphasized, however, that this research was not planned to study the influence upon the protein katabolism of the ingestion of the various foods studied. The non-protein respi- ratory quotient is not of special significance in this research and it is deemed unwise to expand the data by including it, especially as it may be computed from the values for the nitrogen excretion as follows : From the computations of Zuntz it is assumed, for the period in which the non-protein quotient is desired, that for each gram of nitro- gen determined in the urine 5.91 liters of oxygen are absorbed and 4.75 liters of carbon dioxide are produced. The values obtained by multi- plying these amounts of oxygen and carbon dioxide by the grams of nitrogen are considered to represent the carbon dioxide produced and oxygen consumed in the disintegration of the protein. Since the total oxygen consumption and carbon-dioxide production are determined, the subtraction of the amounts resulting from the katabolism of protein gives the liters of oxygen absorbed and carbon dioxide produced in the katabolism of fat and carbohydrate; the quotient from the division CO of the amounts so obtained, -^p, will thus be the non-protein respira- tory quotient. If it is further desired to compute the heat produced by the katab- olism of body material, the grams of nitrogen in the urine multiplied by 26.51 calories1 will give the heat production resulting from the oxidation of protein. By employing the calorific value of oxygen found in the table of Zuntz2 for the non-protein quotient obtained in the above calculation, the heat that should result from the katabolism of the fat and carbohydrate is obtained. The sum of these computed values for protein and for fat and carbohydrate constitutes the heat produced (computed) for the period under observation. In discussing the results of the experiments with carbohydrates, the experiments made with the Middletown and Boston calorimeters will first be considered and subsequently those made with the respiration apparatus in Boston. Except in one instance, the experiments in Middletown were carried out in 2-hour periods; in the Boston experi- ments the periods were only an hour in length, and the basal metabo- lism was usually determined on the same day. , Oppenheimer's Handbuch der Biochemie, 1911, 4 (1), p. 279. 2Zuntz and Schumburg, Physiologic des Marsches, 1901, p. 361. 176 FOOD INGESTION AND ENERGY TRANSFORMATIONS. STATISTICS OF CALORIMETER EXPERIMENTS. The results of all of the calorimeter experiments with carbohydrates are given in tables 101 to 122. Statistical data regarding these experi- ments, not included in the tables or the discussion, are as follows: A. H. A/., 8h52m a. m. to 4h52m p. ro., April 1, 1907. 65.2 kilograms.- Urinated 7h35m a. m. and 12h58m p. m.; drank water (28 grams) at Ih10m p. m. Subject sat quietly most of experimental period, reading much of time. Slight nausea from sugar half hour after taking. Body-temperature: 36.86°, 36.84°, 36.84°, 36.85°, 36.93° C. Pulse rate, 55; respiration rate, 17. A. W. W., 8hl£m a. m. to 12*12m p. m., May 28, 1907. 56.6 kilograms.— Urinated at 7h10m a. m. and at end of each period; drank water at beginning of each period (total amount, 501 grams). Quiet throughout experiment; fell asleep for a few minutes in third period; read most of time. Body-temper- ature: 36.36°, 36.39°, 36.47°, 36.53°, 36.57° C. Pulse rate, 58; no records of respiration rate. F. M. M., 9h30m a. m. to 4h30m p. m., January 31, 1910. 61.6 kilograms. 2 basal periods. — But little activity aside from telephoning at least once in each period and urinating at beginning of first period after taking sugar. In fourth period after sugar, fell asleep several times and was asleep much of period; also fell asleep during last period, but was told to stay awake and slept but little afterwards. Drank 18 grams water after taking sugar and lemon solution. F. M. M., 8h51m a. m. to 2*51m p. m., February 2, 1910. 61.7 kilograms. (2 basal periods). — Urinated 7h40m a. m. and 3 p. m. During basal periods somewhat restless. After sucrose, drank 29 c.c. water; somewhat restless at times in following periods; complained of headache and did not feel very well. Basal periods: pulse rate, 65; respiration rate, 14. After sucrose: pulse rate, 62; respiration rate, 14. Dr. R., 9h03™ a. m. to 5h03m p. m., February 21, 1907. 50.3 kilograms. — Urinated at 7h30m a. m. and in every period but first; drank water at beginning of each period (total amount, 442 grams). Quiet throughout experiment, reading most of time. Found it difficult to eat all the food. Could not breathe easily in last two periods, possibly due to a cold. Pulse rate, 86; respi- ration rate, 17. A. H. M., 8h39m a. m. to 4h39m p. m., March 28, 1907. 65 kilograms.- Enema at 7h15m a. m.; urinated at 6 a. m. and 12h48m p. m. Unable to eat as large an amount of the food as had been provided without danger of nausea. Drank water with food (144 grams); also in second and third periods (181 grams) . Comparatively quiet, reading much of the time. Body-temperature : 36.93°, 37.09°, 36.92', 36.90°, 37.09° C. Pulse rate, 63; respiration rate, 19. A. L. L., 8h18m a. m. to 4h18m p. m., May 13, 1907. 73.1 kilograms.- Urinated 6 a, m., 10 24m a. m. Drank water at beginning of first period (144 grams) and again at beginning of second period (117 grams). Very quiet throughout experiment, reading nearly all of time; dull headache during a part of experiment, which increased towards end, especially in last hour or two. Body-temperature: 36.85°, 36.80°, 36.82°, 36.67°, 36.83° C. Pulse rate, 63; respiration rate, 19. E. H. B., Sh24m a. m. to 4*24™ p. m., May 14, 1907. 72.9 kilograms.- Urinated at 7h15m a. m. Drank water about 8h32m a. m., also at beginning of third period (total amount, 225 grams). Quiet throughout experiment, reading most of time; slight headache after eating food. Body-temperature: 37.01°, 37.11°, 37.10°, 36.69°, 36.89° C. Pulse rate, 59; respiration rate, 20. INGESTION OF CARBOHYDRATES. 177 J. J. C., 9h07m a. »>. l<> 3h07m p. m., March 4, 1910. 65.0 kilograms. 2. basal periods.— Urinated 7h20m, 9h15m, 10h15m a. m., Ih15m, 2h15m, 3h18m p. m. Basal periods: pulse rate, 04; respiration rate, 20. After food: pulse rate, 63; respiration rate, 19. A. L. L., 8h40m a. m. to 4h40m p. m., March 30, 1906. 68 kilograms.— Urinated 7h15m a. m. and 4h55m p. m. Very quiet throughout experiment, reading most of time; appeared to doze twice, being awakened in third period. Body-temperature: 36.61°, 36.69°, 36.65°, 36.51°, 36.44° C, Pulse rate, 65; respiration rate, 19. H. R. D., 8h45m a. m. to 4h45m p. m., March 31, 1906. 59.3 kilograms.— Urinated 7h25m a. m. (after enema), 12h45m p. m., 4h45m p. m., 7h05m p. m. Sat quietly reading about half of time and writing approximately li hours. Body-temperature: 36.64°, 36.92°, 36.90°, 36.86°, 36.59° C. Pulse rate, 78; respiration rate, 20. A. H. M., 8h57m a. m. to 4h57m p. m., April 2, 1906. 67.5 kilograms.— Urinated 6h45m a. m., 1 p. m., 7h10m p. m.; took enema before entering calo- rimeter chamber; slight desire to defecate. Body-temperature : 36.51°, 36.76°, 36.51°, 36.46°, 36.32°, 36.05° C. Pulse rate, 65; respiration rate, 20. A. L. L., 9 a. m. to 9 p. m., April 19, 1906. 67.6 kilograms. — Urinated 7h20m a. m. ; sat quietly reading during experiment except when urinating and telephoning at beginning of each period; near end of last period, asleep; very hungry at night, Body-temperature: 36.86°, 36.84°, 36.73°, 36.67°, 36.61°, 36.65°, 36.15° C. Pulse rate, 64; respiration rate, 18. H. R. D., 8h10m a. w. to 6h10m p. m., April 21, 1906. 59.4 kilograms.— Urinated at beginning of each period; otherwise very quiet, reading about two hours and rest of time idle. Body-temperature: 36.97°, 36.93°, 37.01°, 36.88°, 36.84°, 36.85° C. Pulse rate, 78; respiration rate, 19. J. J. C., 10h56m a. m. to 5h56m p. m., April 7, 1909. 67.6 kilograms. 3 basal periods.— Urinated 6h45m, Ilh06ra a. m., 2h06ra, 6h03m p. m. Fell asleep several times during experiment; wakened from sound sleep at 12h58m p. m. and 3h56m p. m. Basal periods: pulse rate, 60; respiration rate, 18. Food periods: pulse rate, 71; respiration rate, 20. F. M. M., 10h24m a. m. to 4}^4m p. m,, April 8, 1909. 59.4 kilograms. 3 basal periods. — Urinated and defecated at 9h05m a. m., urinated at Ih32m p. m. and immediately after experiment. At end of third basal period, asleep for about 20 minutes, waking up just before end of period, then unusually active. Considerable telephoning at beginning of periods in connection with weighings. Restless during last food period. Basal periods: pulse-rate, 52; respiration rate, 15. After food: pulse rate, 57; respiration rate, 17. F. M. M., 9h38m a. m. to 3h38m p. m., February 8, 1910. 61.8 kilograms. 2 basal periods. — Urinated 7 a. m., Ilh40m a. m., 3h50m p. m. Drank water 9h45m, 10h58m, Ilh55m a. m., 12h55ra p. m. (230 grams in all). At end of first basal period and beginning of second, restless. During last food period, asleep part of time but quite restless whenever awake; was required to press push button to ring bell outside, thus indicating that he was awake. Basal periods : pulse rate, 61; respiration rate, 13. Food periods: pulse rate, 59; respira- tion rate, 14. Dr. H., 9h%4m a. m. to 2h24m p. m., February 14, 1910. 66.6 kilograms. 2 basal periods.— Urinated 8, 9h28m, Ilh32m a. m., Ih30m, 2h30m p. m. Drank water Ilh36m a. m. (135 grams). Basal periods: pulse rate, 58; respiration rate, 13. Food periods: pulse rate, 61; respiration rate, 14. Dr. H., 9h31m a. m. to 3h31m p. m., February 17, 1910. 66.0 kilograms. 2 basal periods.— Urinated 8, 9h40ra, Ilh36m a. m., 2h50m, 3h31ra p. m. Drank 178 FOOD INGESTION AND ENERGY TRANSFORMATIONS. water at HM5m a. m. (112 grams). Basal periods: pulse rate, 59; respiration rate, 12. Food periods: pulse rate, 62; respiration rate, 13. //. B. W., 9b14m a. m. to 5h14m p. m., April 9, 1907. 62.6 kilograms.— Defecated before coming to laboratory; urinated at 8h20m a. m. Very quiet nearly all of experimental period, most movement being in second and third periods. Head ached last period, probably due to reading steadily. Body- temperature: 36.80°, 36.79°, 36.85°, 36.93°, 36.97° C. Pulse rate, 59; respira- tion rate, 18. A. H. M., 9h23m a. m. to 5h%3m p. m., April 10, 1907. 66.6 kilograms.— Urinated 7h30m, Ilh32m a. m., 3h30m p. m.; attempted to urinate at Ih30m p. m. Somewhat restless throughout experiment but did not rise from chair; reading much of time; seldom motionless for more than half minute at a time; difficult to get records of respiration and pulse rates; in last period more quiet; slight headache in afternoon. Body-temperature: 36.76°, 36.70°, 36.84°, 36.80°, 36.78° C. Pulse rate, 63; respiration rate, 19. A. L. L., 8h30m a. m. to 4h30m p. m., May 27, 1907. 74.7 kilograms.— Urinated 7h05m a m. ; very quiet during experiment; fell asleep in second period and had to be awakened; also slept for short time in last period. Body-tem- perature: 36.62°, 36.28°, 36.22°, 36.12°, 36.20° C. Pulse rate, 61; respiration rate, 18. DISCUSSION OF CALORIMETER EXPERIMENTS. SUCROSE. Four experiments were made with sucrose, one each with A. H. M. and A. W. W. with the respiration calorimeter in Middletown, and two with F. M. M. with the chair calorimeter in Boston. A. H. M., April 1, 1907. — This experiment was the first in this re- search in which a pure carbohydrate was ingested. The amount taken was 191 grams, with a total energy value of 756 calories. An inspec- tion of table 101 shows a considerable increase in the carbon-dioxide production after food which persisted during the first three periods but does not appear in the last period. The oxygen consumption shows a marked increase in the first period, with a return to the basal value immediately thereafter. High respiratory quotients, which usually follow the ingestion of sugar, were found in the first two periods with a quotient approximating basal in the last period. The striking abnor- mality in the values for this experiment is the fact that the oxygen increment appears only in the first period, while the increase in the heat production continues throughout all four periods. An explana- tion of this on any other ground than that of unrecognized faulty technique is at present very difficult. As there were certain discrepancies in the measurements of the rectal temperature which led us to consider the records doubtful, it seemed desirable to compare the direct measurements of the heat output with the values calculated from the gaseous metabolism. For this particu- lar experiment, therefore, the values obtained by indirect calorimetry are also recorded, although it should again be emphasized that the values for the indirect heat are not given for the specific purpose INGESTION OF CARBOHYDRATES. 179 of noting the increment above the basal value but simply to obtain the general trend of the metabolism from period to period for comparison with the direct measurements of the heat production. Aside from the first period, in which the computed heat is 16 calories higher than the determined, all the values found by direct calorimetry are higher than those computed. The average for the entire experiment shows a discrepancy between the values obtained by the two methods of approximately 6 per cent. While this discrepancy appears very large in the light of the recent exact work of Du Bois, it should be remem- bered that this particular calorimeter had a very large volume and was primarily designed for 24-hour experiments. The lack of agree- ment between the direct and indirect calorimetry in these short periods is, therefore, not so incongruous as at first sight appears. It should be noted that for computing the increment in the heat production by the indirect method the basal value computed by indirect calorimetry (152 calories) was used in place of the basal value of 164 calories given at the head of table 101, which was obtained by direct calorimetry. The non-protein respiratory quotients are not here tabulated, but have all been computed and used in obtaining the heat production by the indirect method. In general they are two to three points higher than the respiratory quotients recorded, as is the case in practically all of the experiments in this report. TABLE 101.— A. H. M., April 1, 1907. Sitting. (2-hour periods.) Sucrose:1 Amount, 191 grams; energy, 756 cals. ; from carbohydrates, 100 p. ct. Basal lalues (March 6 and 9, 1907): COz, 51 grams; Oa, 46 grams; heat, 164 cals. Time elapsed Nitrogen Carbon dioxide. Oxygen. Heat. Respi- since subject finished eating.1 in urine per 2 hours. Total. Increase. Total. Increase. Determined. Com- puted. ratory quo- tient. Total. Increase. gram. grams. grams. grams. grams. cals. cals. cals. i to 2j hours 0.952 79 28 60 14 192 28 208 0.95 2j-to 4j hours .952 60 9 46 0 185 21 158 .95 4j^to 6j hours .81 56 5 47 1 174 10 159 .86 6J to 8j hours .81 51 0 45 -1 173 9 152 .82 Total 246 42 198 14 724 68 677 .... 1Subject took sugar, together with 119 grams water, in 25 minutes. 2Sample included amount for about an hour preceding the taking of sugar. .4. W. W., May 28, 1907.— A much smaller amount of sugar (80 grams, with an energy value of 317 calories) was taken in this experi- ment as compared with that eaten in the preceding experiment. The periods were but an hour in length instead of 2 hours, as in the experi- ment with A. H. M. ; the wisdom of attempting to shorten the measure- ments of the metabolism to 1 hour is, however, questionable. The 180 FOOD INGESTION AND ENERGY TRANSFORMATIONS. results obtained are given in table 102. Practically the entire increment in the carbon-dioxide production was found in the first hour. The oxygen consumption showed almost no increase after the ingestion of the carbohydrate; in fact, there was a total decrease of 5 grams. The slight increase in the heat production in the first two periods was in part compensated by an actual loss in the subsequent periods. It would appear probable from these data that the basal value selected for this experiment should not properly be used, especially in view of the fact that it is an average of two values obtained some two months before the experiment with sugar was made, i. e., on March 15 and 21, 1907. The specially significant points in connection with this experiment are that the carbon-dioxide production increased in the first hour and that nearly all of the respiratory quotients were some- what high. The fact that two of these quotients were as high as 1.19 and 1.10 throws considerable doubt upon the accuracy of the measure- ments of the oxygen consumption. The values for this experiment are presented chiefly as an illustra- tion of the difficulty of studying problems of this kind when small amounts of ingested material are used, an attempt is made to lower the period of measurement to one hour with so large a calorimeter as that used in Middletown, and an apparently defective basal value is selected which was obtained several months previous to the experiment. TABLE 102.— A. W. W., May 28, 1907. Sitting. (1-hour periods.) Sucrose: Amount, 80 grams; energy, 317 cals. ; from carbohydrates, 100 p. ct. Basal values (March 15 and 21, 1907): CO.;, 25 grams; Oj, 21 grams; heat, 78 cals. Time elapsed since subject Nitrogen Carbon dioxide. Oxygen. Heat. Respira- finished eating. in urine per hour. Total. Increase. Total. Increase. Total. Increase. tory quotient. gram. grams. grams. grams. grams. cals. cals. J to lj hours 0.31 38 13 23 2 84 6 1.19 1 J to 2 i hours .31 26 1 19 o 83 5 1.02 2j to 3^ hours .27 21 -4 19 -2 74 -4 .80 3i to 4^ hours .27 27 2 18 -3 77 -1 1.10* Total. . . . 112 12 79 — 5 318 6 F. M. M., January 31, 1910. — In the first Boston experiment the subject took 100 grams of sucrose and the juice of one lemon with a total energy value of 408 calories. The data given in table 103 for this experiment show an increase in the carbon-dioxide production for the first three periods and a slight increase in the oxygen consumption with measurable increase in heat production. Thus all three factors INGESTION OF CARBOHYDRATES. 181 indicate an increment in metabolism as a result of the ingestion of sugar. As a rule, the respiratory quotients were characteristically high. The basal value used for this experiment was an average of four values, one obtained on the morning of the same day and the others determined at intervals in the following three weeks. The total increments of 18 grams of carbon dioxide, 4.5 grams of oxygen, and 19 calories of heat over the basal value in the course of 5 hours show a definite effect on the metabolism as a result of the ingestion of sugar. TABLE 103.— F. M. M., January 31, 1910. Sitting. (1-hour periods.) Sucrose: Amounts, 100 grams sucrose, and juice of one lemon; energy, 408 cals.; from carbohydrates, 100 p. ct. Nitrogen in urine, 0.53 gram per hour. Basal values (January 31 to February 19, 1910) : COt, 26.5 grams; 62, 23.0 grams; heat,1 80 cals. On January 31, 1910, respiratory quotient, 0.86; nitrogen in urine, 0.54 gram per hour. Time elapsed since subject finished eating. Carbon dioxide. Oxygen. Heat.1 Respiratory quotient. Total. Increase. Total. Increase. Total. Increase. 0 to 1 hours2 grams. 32.5 35.0 31.0 25.5 26.5 grams. 6.0 8.5 4.5 -1.0 0.0 grams. 25.0 25.5 26.0 21.0 22.0 grams. 2.0 2.5 3.0 -2.0 -1.0 cals. 89 83 88 80 79 cals. 9 3 8 0 -1 0.94 .99 .87 .89 .87 1 to 2 hours 2 to 3 hours 3 to 4 hours 4 to 5 hours Total 150.5 18.0 119.5 4.5 419 19 lHeat eliminated corrected for change in body-weight, but not for change in body-temperature 2Subject finished drinking solution (373 grams) 12 minutes after the beginning of this period TABLE 104.— F. M. M., February 2, 1910. Sitting. (1-hour periods.) Sucrose: Amounts, 100 grams sucrose and juice of one lemon; energy, 408 pals.; from carbohydrates, 100 p. ct. Nitrogen in urine, 0.60 gram per hour.1 Basal values (February 2, 1910): COj, 27.5 grams; O-2, 23.5 grams; heat,2 78 cals.; respiratory quotient, 0.86. Time elapsed since subject finished eating. Carbon dioxide. Oxygen. Heat.2 Respiratory quotient. Total. Increase. Total. Increase. Total. Increase. 0 to 1 hours' grams. 33 . 5 34.5 29.0 27.5 grams. 6.0 7.0 1.5 0.0 grams. 26.5 25.5 24.5 22.5 grams. 3.0 2.0 1.0 -1.0 cals 85 83 82 78 cals. ••» t 5 4 0 0.91 .98 .86 .89 1 to 2 hours 2 to 3 hours 3 to 4 hours Total 124.5 14.5 99.0 5.0 328 16 1Sample included amount for 3j hours without food preceding experiment. 2Heat eliminated corrected for change in body-weight, but not for change in body-temperature. 3Subject drank solution (386 grams) at beginning of this period. 182 FOOD INGESTION AND ENERGY TRANSFORMATIONS. F. M. M., February 2, 1910. — In the second sucrose experiment with this subject the same amounts of sugar and lemon juice were taken as in the first experiment. The basal value was determined immedi- ately prior to the values after food. The data given in table 104 show an increment in the carbon-dioxide production, a slight increment in the oxygen consumption, and a perceptible increment in the heat pro- duction in the first three periods. High respiratory quotients are also recorded. MALTOSE-DEXTROSE MIXTURE. The only pure carbohydrate used in the calorimeter experiments was sucrose. The fear of digestive disturbances, which subsequent experimenting proved groundless, led us to consider the possibility of some other type of sugar and a patent preparation was therefore used. The results of four analyses of this material show, on the aver- age, about 39 per cent of maltose, 27 per cent of dextrose, and 34 per cent of water. Four experiments were made with this material in Middletown, and one with J. J. C. in Boston. Dr. R., February 21, 1907.— In the first experiment with this food material 458 grams were eaten, with a total energy of 1,382 calories. From the analysis it can be seen that a considerable part of the material was water and that the dry matter was practically pure carbohydrate. This subject had previously used the maltose-dextrose mixture in his daily diet and was thus accustomed to it. In all of the four 2-hour periods a striking rise in the carbon-dioxide production was noted. (See table 105.) Singularly the oxygen consumption was almost invariably below the basal requirement, which, in this instance, was determined on the preceding day. This deficiency we are unable to explain. The heat production was increased during all of the four TABLE 105. — Dr. R., February 21, 1907. Sitting. (2-hour periods.) Maltose-dextrose mixture: Amount, 458 grams; energy, 1,382 cals. ; from carbohydrates, 100 p. ct. Basal values (February 20, 1907): CO2, 48 grams; Oi, 45 grams; heat,1 146 cals. Nitrogen in urine, 0.55 gram per 2 hours (February 21, 1907). Time elapsed since subject Nitrogen in urine Carbon dioxide. Oxygen. Heat.1 Respira- finished eating per 2 hours. Total. Increase. Total. Increase. Total. Increase. tory quotient. (jram. grams. grams. (jrams. grams. cals. cals. J to 2j hours. 0.782 62 14 38 -7 158 12 1.19 2J to 4j hours. .59 63 15 46 1 163 17 .98 4 J to 6J hours . .58 64 16 43 _2 169 23 1.09 6 J to 8i hours . .75 66 18 42 -3 168 22 1.16 Total 255 63 169 -11 658 74 •Heat eliminated corrected for change in body-weight,but not for change in body-temperature. 'Sample included amount for about lj hours preceding hiking of maltose-dextrose mixture. INGESTION OF CARBOHYDRATES. 183 periods, this being in conformity with the increase in the carbon- dioxide production. The abnormal values for the oxygen consumption in part explain the high respiratory quotients, which are, in two in- stances, 1.19 and 1.16. In all probability there was an error in the measurement of the oxygen consumption. .4. H. A/., March 28, 1907. — The results obtained after the subject had taken 307 grams of the maltose-dextrose mixture, with an energy value of 927 calories, are given in table 106. During the four 2-hour periods there was the usual noticeable increase in the carbon-dioxide production, a total increase of 15 grams in the oxygen consumption, and in every period an increase in the heat production, although the increase in the latter factor was but slight in the fourth period. The general picture points towards a distinct increase in the metabolism after the ingestion of the maltose-dextrose mixture. The respiratory quotients were high, as would be expected; the last value is undoubt- edly erroneous. TABLE 106.— A. H. M., March 28, 1907. Sitting. (2-hour periods.) Maltose-dextrose mixture:1 Amount, 307 grams; energy, 927 cals.; from carbohydrates, 100 p. ct. Basal values (March 6 and 9, 1907) : CO2, 51 grams; Oo, 46 grams; heat, 164 cals. Time elapsed since subject Nitrogen in urine Carbon dioxide. Oxygen. Heat.2 Respira- finished eating.1 per 2 hours. Total. Increase. Total. Increase. Total. Increase. tory quotient. grams. grams. grams. grams. proms. cals. cals. 4 to 2 i hours . 1.11s 70 19 52 6 210 46 0.98 2J to4| hours. l.ll3 70 19 48 2 190 26 1.07 4§ to 6J hours. .99 55 4 44 -2 183 19 .92 6 Ho 8 i hours. .99 57 6 55 9 167 3 .76 Total 252 48 199 15 750 94 Subject took maltose-dextrose mixture, together with 144 grams water, in 17 minutes. 2Heat eliminated corrected for change in body-weight, but not for change in body-temperature. 'Sample included amount for about 2 hours preceding taking of maltose-dextrose mixture. A. L. L., May 13, 1907.-— The subject took 299 grams of the mal- tose-dextrose mixture with an energy value of 902 calories. Accord- ing to the data in table 107, the carbon-dioxide production increased considerably in the first three periods, but practically no increment was found in the oxygen consumption. A distinct increase in the heat pro- duction may be noted in the first two periods ; the values in the last two periods were irregular, but on the average there was clearly an incre- ment in the last 4 hours. The respiratory quotients were extraordi- narily high, this being due in part to the increment in the carbon- dioxide production and in part to the absence of increment in the ox}rgen consumption. The values for the oxygen consumption, which show a definite decrease in the last three periods, are obviously wrong. 184 FOOD INGESTION AND ENERGY TRANSFORMATIONS. TABLE 107.— A. L. L., May 13, 1907. Sitting. (2-hour periods.) Maltose-dextrose mixture: Amount, 299 grams; energy, 902 cals.; from carbohydrates, 100 p. ct. Basal values (May 4, 1907): CO", 51 grams; Oz, 43 grams; heat,1 158 cals. Time elapsed since subject Nitrogen in urine Carbon dioxide. Oxygen. Heat. Respira- finished eating. per 2 hours. Total. Increase. Total. Increase. Total. Increase. tory quotient. gram. grams. yyaws. grams. grams. cals. cals. £ to 2{ hours . 0.702 69 18 44 1 178 20 1.15 2\ to 4} hours. .65 67 16 42 -1 174 16 1.17 4j to 6j hours . .65 60 9 37 -6 155 -3 1.18 &l to 8£ hours . .65 52 1 42 -1 165 7 .90 Total . 248 44 165 -7 672 40 1Heat eliminated corrected for change in body- weight, but not for change in body-temperature. 2Sample included amount for about 2 hours preceding the taking of maltose-dextrose mixture. E. H. B., May 14, 1907.— The subject was given 431 grams of the maltose-dextrose mixture with an energy value of 1,301 calories. An examination of table 108 shows the usual striking increase in the carbon-dioxide production throughout the entire experiment. There was also an increase in the oxygen consumption in the first period, with practically no change in the subsequent periods, and an increase in the heat production in the first three periods with a slight loss in the last period. The evidence clearly points towards a distinct increase in metabolism as a result of the ingestion of carbohydrate. TABLE 108.— E. H. B., May 14, 1907. Sitting. (2-hour periods.) Maltose-dextrose mixture: Amount, 431 grams; energy, 1,301 cals.; from carbohydrates, 100 p. ct. Nitrogen in urine 1.20 grams per 2 hours. Basal values (March 7 and 13, 1907): CO2, 58 grams; Oi( 48 grams; heat, 179 cals. Time elapsed eince subject finished eating.1 Carbon dioxide. Oxygen. Heat.2 Respiratory quotient. Total. Increase. Total. Increase. Total. Increase. 0 to 2 hours grams. 74 73 73 65 grams. 16 15 15 7 grams. 54 47 50 46 grams. 6 1 2 2 cals. 199 189 191 176 cals. 20 10 12 3 0.99 1.13 1.05 1 04 2 to 4 hours 4 to 6 hours 6 to 8 hours Total 285 53 197 5 755 39 'Subject took maltose-dextrose mixture in 30 minutes. 2Heat eliminated corrected for change in body-weight, but not for change in body- temperature. J. J. €., March 4, 1910. — Following the ingestion of 145 grams of maltose-dextrose mixture and the juice of one lemon, with a total energy value of 440 calories, positivte increases were found for the INGESTION OF CARBOHYDRATES. 185 carbon-dioxide production in all of the periods and an increment in both the oxygen consumption and the heat production in the first three periods. (See table 109.) With this subject it is clearly evident from the general picture that this amount of maltose-dextrose mixture produced a positive increase above the basal metabolism. Although the respiratory quotient in the first two periods was unusually low, it rose until in the fourth period it was slightly over 1 . TABLE 109. — J. J. C., March 4, 1910. Sitting. (1-hour periods.) Maltose-dextrose mixture:1 Amounts, 145 grams maltose-dextrose mixture, juice of one lemon; energy, 449 cals. ; from carbohydrates, 100 p. ct. Basal values (March 4, 1910): CO2, 26.0 grams; Oa, 22.0 grams; heat (computed), 74 cals.; respiratory quotient, 0.86. Nitrogen in urine, 0.47 gram per hour. Time elapsed since subject finished eating.1 Nitrogen in urine per hour. Carbon dioxide. Oxygen. Heat (computed). Respira- tory quotient. Total. Increase. Total. Increase. Total. Increase. gram . grams. grams. grams. grams. cals. cals. 0 to 1 hours . . . 0.462 29.0 3.0 24.5 2.5 82 8 0.80 1 to 2 hours . . . .462 33.0 7.0 28.0 6.0 95 21 .86 2 to 3 hours . . . .44 33.0 7.0 25.5 3.5 88 14 .93 3 to 4 hours . . . .43 29.0 3.0 20.5 -1.5 72 _2 1.01 Total .... 124.0 20.0 98.5 10.5 337 41 'Subject finished drinking solution (333 grams) in 17 minutes after the beginning of this period. The drinking occupied 4 minutes. 'Sample included amount for about 1 hour preceding the taking of maltose-dextrose mixture. BANANAS AND SUGAR. Bananas and sugar were given in several experiments, as considerable amounts could be consumed and the total energy intake in the form of carbohydrate thus be greatly increased. The results of 7 experiments follow; the experiments with A. L. L., H. R. D., and A. H. M. were made in Middletown, and those with J. J. C. and F. M. M. in Boston. A. L, L., March 30, 1906 (765 grams bananas and 99 grams sugar, with a total fuel value of 1,109 calories). — A very large increase in the carbon-dioxide production was found in the first period, this being decreased about one-half in the second period. (See table 110.) In the last two periods the amount was essentially the same as the basal value. There was an increase of 17 grains in the oxygen consumption in the first period with practically basal values thereafter. The heat production showed a large increase for the first two periods, but the values were essentially the same as the basal in the last two periods. The respiratory quotients were extraordinarily high and characteris- tic of those following carbohydrate ingestion. In this experiment, therefore, there was a somewhat closer uniformity between the gaseous metabolism and heat production than in many of the earlier experi- 186 FOOD INGESTION AND ENERGY TRANSFORMATIONS. ments. All of the factors indicate a considerable increase in the actual metabolic processes. TABLE 110. — A. L. L., March 30, 1906. Sitting. (2-hour periods.) Bananas and sugar: Amounts, 765 grams bananas, 99 grams sugar; nitrogen, 1.58 grams; total energy, 1,123 cals. Fuel value: Total, 1,109 cals.; from protein, 3 p. ct.; from fat, 4 p. ct.; from carbohydrates. 93 p. ct. Nitrogen in urine, 0.73 gram per 2 hours. Basal values (April 3 and 6, 1906) : CC>2, 47 grams; Oz, 43 grams; heat, 145 cals. Time elapsed since subject finished eating.1 Carbon dioxide. Oxygen. Heat. Respiratory quotient. Total. Increase. Total. Increase. Total. Increase. 0 to 2 hours grams. 80 65 49 50 grams. 33 18 2 3 grams. 60 42 36 40 grams. 17 -1 -7 -3 cals. 195 183 151 139 cals. 50 38 6 -6 0.97 1.13 1.00 .90 2 to 4 hours 4 to 6 hours 6 to 8 hours Total 244 56 178 6 668 88 .... lSubject ate food in 31 minutes. H. R. D., March 31, 1906. (1,173 grams bananas and 103 grams sugar, with a total fuel value of 1,562 calories). — The data given in table 111 show large increases in the carbon-dioxide excretion over the basal value in the first three periods. There was a concordant increase in the oxygen consumption and an increment in the heat production. We thus have here practically the same picture with all three factors of metabolism, indicating an increased metabolism following the inges- tion of bananas and sugar. TABLE lll.—H. R. D., March 31, 1906. Sitting. (2-hour periods.) Bananas and sugar: Amounts, 1,173 grams bananas, 103 grams sugar; nitrogen, 2.43 grams; total energy, 1,583 cala. Fuel value: Total, 1,562 cals.; from protein, 4 p. ct.; from fat, 4 p. ct.; from carbohydrates, 92 p. ct. Nitrogen in urine, 0.78 gram per 2 hours. Basal values (February 6 to April 20, 1906): CO2, 47 grams; Oc, 42 grams; heat, 146 cals. Time elapsed since subject finished eating.1 Carbon dioxide. Oxygen. Heat. Respiratory quotient. Total. Increase. Total. Increase. Total. Increase. 0 to 2 houra grams. 72 69 65 55 grams. 25 22 18 8 grams. 54 52 50 42 grams. 12 10 8 0 cals. 191 182 172 146 cals. 45 36 26 0 0.97 .96 .95 .95 2 to 4 hours 4 to 6 hours .... 6 to 8 hours Total 261 73 198 30 691 107 Subject ate food in 27 minutes. INGESTION OF CARBOHYDRATES. 187 A. H. M., April 2, 1906 (1,121 grams bananas and 86 grams sugar, with a total fuel value of 1,448 calories). — The values for both the carbon-dioxide excretion and the heat production recorded in table 112 indicate an increase in all of the periods of this experiment ; the oxygen consumption also showed an increment in the first three periods. The respiratory quotients were in all cases high, the first quotient being above 1. A fairly uniform picture of increased metabolism was thus shown throughout the entire observation. TABLE 112.— A. H. M., April 2, 1906. Sitting. (2-hour periods.) Bananas and sugar: Amounts, 1,121 grams bananas, 86 grams sugar; nitrogen, 2.34 grams; total energy, 1,468 cals. Fuel value: Total, 1,448 cals.; from protein, 4 p. ct. ; from fat, 4 p. ct. ; from carbohydrates, 92 p. ct. Nitrogen in urine, 0.79 gram per 2 hours.1 Basal values (February 12 and 14, 1906) : CO2, 45 grams; O2, 40 grams; heat, 142 cals. Time elapsed since subject finished eating.2 Carbon dioxide. Oxygen. Heat. Respiratory quotient. Total. Increase. Total. Increase. Total. Increase. 0 to 2 hours grams. 79 68 65 51 grams. 34 23 20 6 grams. 56 52 48 39 grams. 16 12 8 -1 cals. 182 167 166 147 cals. 40 25 24 5 1.03 .95 .98 .96 2 to 4 hours 4 to 6 hours 6 to 8 hours Total 263 83 195 35 662 94 1Sample included amount for about if hours preceding the eating of food. 2Subject ate food in 27 minutes. A. L. L., April 19, 1906 (763 grams bananas and 99 grams sugar, with a fuel value of 1,147 calories).- — In this second experiment with A. L. L. the amounts of bananas and sugar eaten were almost identical with those taken in the experiment of March 30, 1906, but the observa- tions continued for 12 hours instead of for 8 hours, as in the duplicate experiment. The results are given in table 113. The carbon-dioxide excretion remained above the basal value in all of the six periods, although the increases in the first two periods were the most striking. An increase in oxygen consumption was found in the first and second periods, with slight variations above or below the base-line in the fol- lowing periods. The increase in heat production was very marked in the first three periods. A striking anomaly is a decrease of 25 calories in the last period, illustrating one of the defects of short-period deter- minations with this large calorimeter. The general picture with all three factors is a noticeable increase in the metabolism. The total increases in these duplicate experiments do not give a wholly satisfactory comparison. Thus, in the experiment of March 30 there was an increase in the carbon-dioxide excretion of 56 grams, while 188 FOOD INGESTION AND ENERGY TRANSFORMATIONS. in that of April 19 it was 74 grams. If the 7 grams increment noted in the last two periods of the experiment on April 19 be deducted, the increment for the first four periods would be 67 grams as compared with the 56 grams for the same period of time on March 30. In both experi- ments the oxygen increment appeared in the first period and was not far from the same in the two experiments. The increase in the heat production was 88 calories in the first experiment and but 72 calories in the second. If, however, the results of the last period of the second experiment be omitted, the increment would be 97 calories, or a little larger than that found in the first experiment. In general the two experiments may be said to be in fair agreement, as both indicate a noticeable rise in heat production following the ingestion of bananas and sugar. TABLE 113.— A. L. L., April 19, 1906. Sitting. (2-hour periods.) Bananas and sugar: Amounts, 763 grams bananas, 99 grams sugar; nitrogen, 1.58 grams; total energy, 1,160 cals. Fuel value: Total, 1,147 cals.; from protein, 3 p. ct. ; from fat, 4 p. ct.; from carbohydrates, 93 p. ct. Basal values: (February" to April 6, 1906): CO», 47 grams; C>2, 42 grams; heat, 148 cals. Nitro- gen in urine, 0.71 gram per 2 hours (April 19, 1906). Time elapsed since subject Nitrogen in urine Carbon dioxide. Oxygen. Heat. Respira- finished eating. per 2 hours. Total. Increase. Total. Increase. Total. Increase. tory quotient. gram . grams. grams. grams. grams. cals. cals. j to 2j hours. 0.51 80 33 55 13 194 46 1.06 2^ to 4 £ hours . .86 69 22 47 5 181 33 1.07 4 j to 6 j hours . .72 55 8 40 -2 166 18 .99 6J to8i hours. .59 51 4 42 0 147 -1 .89 8J to 10f hours .54 51 4 39 -3 149 1 .94 10| to 12£ hours .47 50 3 45 3 123 -25 .80 Total .... 356 74 268 16 960 72 H. R. D., April 21, 1906 (1,171 grams bananas and 103 grams sugar, with a total fuel value of 1,561 calories). — This was the second experiment with the subject in which bananas and sugar were taken, the amounts being practically the same as those eaten on March 31, 1906. The observations in this experiment, however, continued for 2 hours longer than in the first experiment. The data are given in table 114. There was a noticeable increase in the carbon-dioxide production, even in the fifth period. Increments were also observed for both the oxygen consumption and the heat production. The respiratory quotients were high, but none of them were over 1. If we omit all of the values found for the last period, the results will be comparable with those obtained in the experiment of March 31 and not dissimilar. In the first experiment the increment for carbon- INGESTION OF CARBOHYDRATES. 189 dioxide production was 73 grams, for oxygen consumption 30 grams, and for heat production 107 calories. In the second experiment the increase in carbon-dioxide excretion for the first four periods was 64 grams, for oxygen consumption 34 grams, and for heat production 116 calories. The nitrogen in the urine per 2 hours was very much greater in this experiment than in the first, averaging 1.23 grams for the first four periods as compared with 0.78 gram in the experiment of March 31 . TABLE 114— H. R. D., April 21, 1906. Sitting. (2-hour periods.) Bananas and sugar: Amounts, 1,171 grama bananas, 103 grams sugar; nitrogen, 2.10 grams; total energy, 1,580 cals. Fuel value: Total, 1,561 cals.; from protein, 3 p. ct.; from fat, 4 p. ct.; from carbohydrates, 93 p. ct. Basal values (February 6 to April 20, 1906): CO2, 47 grama; O2, 42 grams; heat, 146 cals. Nitrogen in urine, 0.97 gram per 2 hours (April 21, 1906). Time elapsed since subject Nitrogen in urine Carbon dioxide. Oxygen. Heat, Respira- finished eating.1 per 2 hours. Total. Increase. Total. Increase. Total. Increase. tory quotient. grams. grams. grams. grams. grams. cals. cals. i to 2 j hours . 1.59 62 15 55 13 180 34 0.82 2 J to 4| hours . 1.52 68 21 57 15 186 40 .87 4 J to 6 J hours . 1.28 64 17 47 5 170 24 .99 6 £ to 8£ hours . .54 58 11 43 1 164 18 .98 SjtolOihours. 1.02 52 5 56 14 167 21 .67 Total . . 304 69 258 48 867 137 Subject ate food in 36 minutes. TABLE 115.— J. J. C., April 7, 1909. Sitting. (1-hour periods.) Bananas and sugar: Amounts, 648 grams bananas, 77 grams sugar; nitrogen, 1.34 grams; total energy, 974 cals. Fuel value: Total, 962 cals.; from protein, 4 p. ct.; from fat, 4 p. ct.; from carbohydrates, 92 p. ct. Nitrogen in urine, 0.40 gram per hour. Basal values (April 7, 1909): COa, 25.5 grams; Oz, 21.5 grams; heat (computed), 72 cals.; respiratory quotient, 0.87. Nitrogen in urine, 0.38 gram per hour. Time elapsed since subject finished eating. Carbon dioxide. Oxygen. Heat (computed) . Respiratory quotient. Total. Increase. Total. Increase. Total. Increase. 0 to 1 hour1 grams. 33.0 36.0 34.5 32.0 grams. 7.5 10.5 9.0 6.5 grams, 26.0 25.5 26.5 25.5 grams. 4.5 4.0 5.0 4.0 cals. 90 89 91 87 cals. 18 17 19 15 0.92 1.02 .96 .92 1 to 2 hours 2 to 3 hours 3 to 4 hours Total 135.5 33.5 103.5 17.5 357 69 LSubject finished eating 28 minutes after the beginning of this period. The eating occupied 20 minutevs. 190 FOOD INGESTION AND ENERGY TRANSFORMATIONS. J. J. C., April 7, 1909 (648 grams bananas, 77 grams sugar, with a total fuel value of 962 calories). — The basal value for this experi- ment was obtained on the same day. The data given in table 115 record a striking increase in carbon-dioxide production for all of the periods, also an increase in oxygen consumption and heat production, the incre- ment of the three factors being reasonably comparable. The respira- tory quotients were high, reaching 1.02 in the second period. We have here, therefore, a distinct increase in the metabolism as measured not only by the respiratory exchange but by the heat production. F. M. M., April 8, 1909 (611 grams bananas, 9 grams sugar, with a total fuel value of 655 calories). — The results obtained in the three 1-hour periods indicate a considerable rise in carbon-dioxide production, oxygen consumption, and heat production, although the increment in the heat production in the last two periods was not very marked. (See table 116.) The respiratory quotients increased from 0.82 to 0.90 as the experiment progressed. TABLE 116.— F. M. M., April 8, 1909. Sitting. (1-hour periods.) Bananas and sugar: Amounts, 611 grams bananas, 9 grams sugar; nitrogen, 1.26 grams; total energy, 666 cals. Fuel value: Total, 655 cals.; from protein, 5 p. ct.; from fat, 5 p. ct.; from carbohydrates, 90 p. ct. Nitrogen in urine, 0.51 gram per hour. Basal values (April 8, 1909): COz, 23.5 grams; O2 20.5 grams; heat,1 79 cals.; respiratory quotient, 0.82. Nitrogen in urine, 0.39 gram per hour. Time elapsed since subject finished eating. Carbon dioxide. Oxygen. Heat.1 Respiratory quotient. Total. Increase. Total. Increase. Total. Increase. 0 to 1 hour2 grams. 30.0 29.5 29.0 grams. 6.5 6.0 5.5 grams. 26.5 24.5 23.5 grams. 6.0 4.0 3.0 cals. 91 82 83 cals. 12 3 4 0.82 .87 .90 1 to 2 hours 2 to 3 hours Total . 88.5 18.0 74.5 13.0 256 19 eliminated corrected for change in body-weight, but not for change in body-temperature. 2Subject finished eating 30 minutes after the beginning of this period. The eating occupied 18 minutes. BANANAS. In February 1910, three experiments were made in Boston with bananas only. One of the subjects had been used in two of the series of experiments previously considered. F. M. M., February 8, 1910 (400 grams bananas, with a fuel value of 406 calories). — In the first two periods there were small increases in the carbon-dioxide production with essentially a basal metabolism in the last two periods. (See table 117.) A slight rise in the oxygen consumption in the first period was in large part compensated by values slightly less than basal in the last three periods. The same general picture was observed with the heat production. The respiratory INGESTION OF CARBOHYDRATES. 191 quotients were very irregular, but no extraordinarily high values were obtained. No pronounced effect upon either the gaseous metabolism or the heat production as a result of the ingestion of bananas is apparent in this experiment. TABLE 117. — F. M. M., February 8, 1910. Sitting. (1-hour periods.) Bananas: Amount, 400 grams; nitrogen, 0.83 gram; total energy, 413 cals. Fuel value: Total, 406 cals.; from protein, 5 p. ct.; from fat, 6 p. ct.; from carbohydrates, 89 p. ct. Nitrogen in urine, 0.46 gram per hour. Basal values (February 8, 1910): CO2, 25.5 grams; Oa, 22.5 grams; heat,1 82 cals.; respiratory quotient, 0.83. Nitrogen in urine, 0.45 gram per hour. Time elapsed since subject finished eating. Carbon dioxide. Oxygen. Heat.1 Respiratory quotient. Total. Increase. Total. Increase. Total. Increase. 0 to 1 hour2 grams. 30.0 28.5 25.5 26.0 grams. 4.5 3.0 0.0 0.5 grams. 28.0 22.0 21.5 20.0 grams. 5.5 -0.5 -1.0 -2.5 cals. 91 79 80 76 cals. 9 -3 -2 -6 0.78 .94 .86 .95 1 to 2 hours 2 to 3 hours 3 to 4 hours Total 110.0 8.0 91.5 1.5 326 -2 eliminated corrected for change in body-weight, but not for change in body-temperature. 2Subject finished eating 17 minutes after the beginning of this period. The eating occupied 10 minutes. Dr. H., February 14, 1910 (403 grams bananas, with a fuel value of 409 calories). — According to the data given in table 118, noticeable increases in the carbon-dioxide production, oxygen consumption, and computed heat production were found. The respiratory quotients were all above 0.90. TABLE 118. — Dr. H., February 14, 1910. Sitting. (1-hour periods.) Bananas: Amount, 403 grams; nitrogen, 0.83 gram; total energy, 416 cals. Fuel value: Total, 409 cals.; from protein, 5 p. ct.; from fat, 6 p. ct.; from carbohydrates, 89 p. ct. Basal values (February 14, 1910): CO2, 22 grams; Oa, 20 grams; heat (computed), 66 cals.; res- piratory quotient, 0.81. Nitrogen in urine, 0.33 gram per hour. Time elapsed since subject finished eating. Nitrogen in urine per hour. Carbon dioxide. Oxygen. Heat (computed). Respira- tory quotient. Total. Increase. Total. Increase. Total. Increase. 0 to 1 hour1 . . 1 to 2 hours . . . 2 to 3 hours . . . Total gram. 0.51 .51 .44 grams. 27.0 28.0 28.5 grams. 5.0 6.0 6.5 grams. 21.5 22.5 21.5 grams. 1.5 2.5 1.5 cals. 73 77 75 cals. 7 11 9 0.91 .90 .95 83.5 17.5 65.5 5.5 225 27 'Subject finished eating 22 minutes after the beginning of this period. The eating occupied 14 minutes. 192 FOOD INGESTION AND ENERGY TRANSFORMATIONS. Dr. H., February 17, 1910 (397 grams bananas, with a fuel value of 403 calories). — There was a marked increase in the carbon-dioxide production in all of the four periods. (See table 119.) The oxygen consumption showed considerable irregularity, although the results as a whole indicated a definite increase. The computations of heat production also gave irregular results, but on the average showed a distinct increase. While this experiment can not be considered as a good duplicate of the experiment on February 14, yet they both imply an increased metabolism as a result of eating bananas. TABLE 119. — Dr. H., February 17, 1910. Silting. (1-hour periods.) Bananas: Amount, 397 grams; nitrogen, 0.83 gram; total energy, 410 cals. Fuel value: Total, 403 cals.; from protein, 5 p. ct.; from fat, 6 p. ct.; from carbohydrates, 89 p. ct. Basal values (February 17, 1910): CO2, 21.5 grams; 62, 20.5 grams; heat (computed), 67 cals.; respiratory quotient, 0.77. Nitrogen in urine, 0.30 gram per hour. Time elapsed since subject finished eating. Nitrogen in urine per hour. Carbon dioxide. Oxygen. Heat (computed). Respira- tory quotient. Total. Increase. Total. Increase. Total. Increase. gram. grams. grams. grams. grams. cals. cals. 0 to 1 hours1 . . 0.43 25.5 4.0 22.0 1.5 74 7 0.83 1 to 2 hours . . . .43 27.0 5.5 20.0 -0.5 69 2 .98 2 to 3 hours . . . .37 28.0 6.5 24.0 3.5 81 14 .85 3 to 4 hours . . . .37 24.5 3.0 18.5 -2.0 65 _2 .96 Total .... 105.0 19.0 84.5 2.5 289 21 Subject finished eating 19 minutes after the beginning of this period. 10 minutes. POPCORN. The eating occupied The use of an insoluble carbohydrate in a fruit (banana) presented certain facilities for the absorption and digestion of carbohydrate that would not obtain if starch were given. To approximate starch and still make the diet fairly palatable, we used popcorn in two of the Middletown experiments. H. B. W., April 9, 1907 (187 grams popcorn, with a fuel value of 796 calories) . — A basal value obtained 5 days before the experiment was used for comparison. Decided increments in the carbon-dioxide production are recorded in table 120 for all periods. A positive incre- ment in oxygen consumption was noted in the first period, with slight fluctuations above or below the basal value in the three remaining periods. An increment in heat production was noted in all four periods, this paralleling the increment found in the carbon-dioxide excretion. The respiratory quotient was high throughout the entire experiment. A. H. M., April 10, 1907 (199 grams popcorn, with a fuel value of 847 calories). — In the second experiment with popcorn an increment INGESTION OF CARBOHYDRATES. 193 TABLE 120.— //. B. W., April 9, 1907. Sitting. (2-hour periods.) Popcorn: Amount, 187 grams; nitrogen, 3.26 grams; total energy, 824 cals. Fuel value: Total, 796 cals.; from protein, 11 p. ct. ; from fat, 11 p. ct. ; from carbohydrates, 78 p. ct. Nitrogen in urine, 0.88 gram per 2 hours. Basal values (April 4, 1907): CO2, 54 grams; O->, 46 grams; heat, 158 cals. Time elapsed since subject finished eating.1 Carbon dioxide. Oxygen. Heat. Respiratory quotient. Total. Increase. Total. Increase. Total. Increase. 1 to 3 hours grams. 65 63 58 60 grams. 11 9 4 6 grams. 53 46 44 48 grams. 1 0 -2 2 cals. 174 167 167 163 cals. 16 9 9 5 0.90 .98 .96 .89 3 to 5 hours 5 to 7 hours 7 to 9 hours Total 246 30 191 7 671 39 Subject ate popcorn in 53 minutes. was found in both the carbon-dioxide production and the oxygen con- sumption for all of the four periods, that for the oxygen consumption being fairly constant. (See table 121.) There was also an increase in the heat production in the first three periods. The respiratory quotient was very high in the first period, then gradually lowered. The positive increments in the carbon-dioxide excretion and heat pro- duction in both experiments with popcorn indicate that the ingestion of this food material has a definite effect upon the metabolism. TABLE 121.— A. H. M., April 10, 1907. Sitting. (2-hour periods.) Popcorn: Amount, 199 grams; nitrogen, 3.47 grams; total energy, 877 cals. Fuel value: Total, 847 cals.; from protein, 11 p. ct.; from fat, 11 p. ct.; from carbohydrates, 78 p. ct. Basal values (March 6 and 9, 1907) : COa, 51 grams; Oj, 46 grams; heat, 164 cals. Time elapsed since subject Nitrogen in urine Carbon dioxide. Oxygen. Heat. Respira- finished eating.1 per 2 hours. Total. Increase. Total. Increase. Total. Increase. tory quotient. grams. grams. grams. grams. grams. cals. cals. | to 2 j hours . 1.22 67 16 49 3 187 23 1.01 2| to 4| hours . 1.24 62 11 50 4 188 24 .89 4 f to 6f hours . 1.24 58 7 51 5 182 18 .84 6| to 8| hours . 1.02 57 6 50 4 165 1 .82 Total .... 244 40 200 16 722 66 Subject ate popcorn in lj hours. 194 FOOD INGESTION AND ENERGY TRANSFORMATIONS. RICE. The changes in the metabolism due to the ingestion of boiled rice were also studied in one experiment in Middletown. A. L. L., May 27, 1907 (652 grams rice, with a fuel value of 432 calories). — As shown in table 122, the carbon-dioxide production was increased in the first two periods only. Owing to defective technique, it was necessary to combine the results for the oxygen consumption in the second and third periods ; practically no increment in this factor was noted. A slight increment in the heat production was found in the first period, but the subsequent results differed but little from the basal value. The respiratory quotients for the first 6 hours were 1 or over. While an increment in the carbon-dioxide production charac- teristic of carbohydrate metabolism is shown clearly in the first two periods, there was no indication in the results obtained for either the oxygen consumption or the heat production that the metabolism increased noticeably as a result of the ingestion of the rice. TABLE 122.— ,1. L. L., May 27, 1907. Sitting. (2-hour periods.) Rice (boiled): Amount, 652 grams; nitrogen, 2.03 grams; total energy, 449 cals. Fuel value: Total, 432 cals.; from protein, 12 p. ct.; from fat, 1 p. ct. ; from carbohydrates, 87 p. ct. Nitrogen in urine, 0.71 gram per 2 hours. Basal values (May 4, 1907): CO2, 51 grams; O2, 43 grams; heat,1 158 cals. Time elapsed since subject finished eating.2 Carbon dioxide. Oxygen. Heat. Respiratory quotient. Total. Increase. Total. Increase. Total. Increase. $ to 2 j hours grams. 66 62 52 51 grams. 15 '!} 0 grams. 46 83 42 grams. 3 -3 -1 cals. 168 311 160 cals. 10 -5 2 1.05 1.00 .89 2 \ to 4 i hours . . . 4 \ to 6 z hours 6J to 8 j hours Total ... . 231 27 171 -1 639 7 eliminated corrected for change in body-weight, but not for change in body-temperature- "Subject ate rice in 20 minutes. GENERAL DISCUSSION OF CALORIMETER EXPERIMENTS WITH CARBOHYDRATES. In the foregoing discussion of the individual calorimeter experiments certain features common to each were pointed out. From the results given in tables 101 to 122, we may conclude that the effect on the car- bon-dioxide excretion was relatively uniform in that a marked increase in the first 1-hour or 2-hour period was followed by considerable increases which gradually decreased in magnitude as the experiment progressed. With the oxygen consumption the increment, when noted, was almost invariably in the first period ; subsequent periods showed such irregularity in values as to allow no other inference than that probably the base-line had been reached. With the heat product ion an increment was again definitely observed, usually in the first period, subsequent periods showing slight fluctuations either above or below the basal value. INGESTION OF CARBOHYDRATES. 195 The conclusion, then, may fairly be drawn that the ingestion of carbohydrate material has a pronounced and continuous effect upon the carbon-dioxide production, which may last 8 hours or more, and increases the oxygen consumption for a short time, generally a little over 2 hours. The respiratory quotient also shows a marked rise. The increase in the oxygen consumption is paralleled by a definite increase in the heat production. The last observation is of the greatest significance in connection with calorimeter experiments, as it demon- strates by direct calorimetry a positive increase in the heat production as the result of the ingestion of varying amounts of carbohydrates. MAXIMUM EFFECT OF CARBOHYDRATE INGESTION ON METABOLISM (DIRECT CALORIMETRY). To what extent the basal heat production may be increased as a result of carbohydrate ingestion may best be shown by considering the data in table 123. In this table the results are grouped according to the carbohydrates studied. The amounts ingested, the total length of observation, and the maximum increase above the basal value are here recorded. The length of time between the taking of the food and the maximum increase is also noted. Unfortunately the calorimeter experiments are not sufficiently num- erous, either as to the number of experiments with each carbohydrate or the number with the same amounts of food, to permit satisfac- tory Comparisons of the relation of the individual carbohydrates to the maximum heat production. It is much to be regretted, also, that more experiments with pure carbohydrates were not made instead of with such mixed carbohydrates as bananas, popcorn, and rice. At the time these studies were made, however, the main purpose was to determine the possible maximum effect of carbohydrate ingestion upon the basal heat production. This is clearly established, as will be seen from the results given in the table. Although, with the pos- sible exception of bananas and sugar, the evidence is not sufficiently complete to allow deductions as to the differences between the indi- vidual carbohydrates, the general picture is tolerably clear. With sucrose it will be seen that the largest amount of heat was pro- duced when the largest amount was ingested. This occurred in the experiment with A. H. M. on April 1, 1907, in which the period of experimenting was 8 hours, subdivided into four 2-hour periods. In this experiment an increment of 17 per cent was found in the period from j to 2| hours after food. A smaller amount of sugar taken by F. M. M. on January 31, 1910, produced an increment of but 11 per cent within one hour of taking the sugar, while a still smaller amount with A. W. W. produced an increase of 8 per cent in approximately the same time. In all cases the maximum increment was found from ^ to 2\ hours or even less after the ingestion of the carbohydrate. 196 FOOD INGESTION AND ENERGY TRANSFORMATIONS. TABLE 123. — Maximum effect of carbohydrate ingestion on heat production. (Calorimeter experiments.) Carbohydrate. Amount. Subject. Date. Length of observa- tion. Greatest increment above basal value. Time elapsed since subject finished eating. Sucrose . grams. 191 A. H. M. Apr. 1, 1907 hours. 8 p. ct. 17 hours. A. to2i Maltose-dextrose mixture 1002 1002 80 458 F. M. M. F. M. M. A. W. W. Dr. R... Jan. 31, 1910 Feb. 2, 1910 May 28, 1907 Feb. 21, 1907 5 4 4 g 11 9 8 16 0 to 1 0 tol i to it 4j to 6J Bananas and sugar: Bananas 431 307 299 1452 11731 E.H.B.. A. H. M. A. L. L.. J.J.C... May 14, 1907 Mar. 28, 1907 May 13, 1907 Mar. 4, 1910 8 8 8 4 11 28 13 28 0 to 2 i to 2| Ito2i 1 to 2 Sugar 103j H. R. D. Mar. 31, 1906 8 31 0 to 2 Bananas 1171\ Sugar 103f H. R. D. Apr. 21, 1906 10 27 2^ to4j Bananas 1121\ Sugar . .... 86/ A. H. M. Apr. 2, 1906 8 28 0 to 2 Bananas . . 765\ Sugar 991 A. L. L.. Mar. 30, 1906 8 34 0 to 2 Bananas 7631 Sugar 99 j A. L. L. . Apr. 19, 1906 12 31 t to2i Bananas i 6481 Sugar . . .... 77 / J. J. C. . . Apr. 7, 1909 4 26 2 to 3 Bananas 611\ Sugar 9/ F. M. M. Apr. 8, 1909 3 15 0 to 1 Bananas 403 Dr. H ... Feb. 14, 1910 3 17 1 to 2 Popcorn . 400 397 199 F. M. M. Dr. H... A. H. M Feb. 8, 1910 Feb. 17, 1910 Apr. 10, 1907 4 4 8 11 21 15 0 tol 2 to 3 22 to 4? Rice 187 652 H. B. W. A. L. L. Apr. 9, 1907 May 27, 1907 8 8 10 6 1 to 3 i to 2J time given represents the experimental period. The food was usually taken less than half an hour before the beginning of the experiment. See tables 101 to 122 for details. 2 Also juice of one lemon. Unlike the experiments with sucrose, the maltose-dextrose experi- ments did not show the highest increment with the largest amount, as the greatest increase (28 per cent) was found with only 145 grams. The first two experiments recorded with the maltose-dextrose mixture are comparable in that the amounts of carbohydrate ingested are approximately the same and show an average increment of 13 to 14 per cent. In one of these experiments, that with Dr. R., the maximum effect was not observed until 4j to 6£ hours after the food was taken. As this subject was particularly satisfactory from the standpoint of technique, we have no explanation for this long-delayed action in secur- ing the maximum value. Two other experiments, which were made with approximately 300 grams of the sugar mixture, do not give very INGESTION OF CARBOHYDRATES. 197 satisfactory duplicate results, as the value found with A. H. M. is more than twice as large as that found with A. L. L., although the time of appearance is practically the same, i. e., in the first 2 hours after food. In comparing the values in this group, it should be noted that in the calculation of the percentage increment the base-line used for J. J. C. was 1 hour, while that for the other subjects of the experi- ments with maltose-dextrose mixture was 2 hours. The first three experiments with bananas and sugar are perfectly comparable in that practically the same amounts of bananas and sugar were given in each case. The increment is strikingly constant, varying only from 27 to 31 per cent. In the two experiments with A. L. L., the amounts ingested were approximately the same and reasonably concordant increments were obtained, i. e., 34 and 31 per cent respec- tively. With somewhat smaller amounts of bananas and sugar, J. J. C. gave an increment of but 26 per cent, while F. M. M., with an ingestion of 611 grams bananas and 9 grams of sugar, showed an incre- ment of but 15 per cent. In three experiments the ingestion of approximately 400 grams of bananas, without sugar, gave an increase in the heat production of 11 to 21 per cent, while in two experiments with popcorn a positive increment of 10 to 15 per cent was found. The experiment with boiled rice showed an increase of 6 per cent. In considering these data it should be remembered that the results for the individual experiments can have but relatively little value, inasmuch as the amounts recorded for the greatest increments above basal requirements represent the observations in a single period and are thus liable to all the errors possible with such measurements. The emphasis should therefore be laid upon the general picture. The values given in this table show that it is perfectly possible for a pure sugar, such as sucrose, to increase the metabolism 17 per cent above the basal value; that a maltose-dextrose mixture can raise it somewhat higher; that bananas and sugar taken together give an increment of 15 to 34 per cent, depending upon the amount ingested; that bananas without sugar increase the heat production on the average 16 per cent; and that popcorn and rice may produce an increment of approximately 13 and 6 per cent respectively. In other words, it is very clear that large increments in the heat production may be expected from a prac- tically protein-free diet. As these values deal only with the maximum periods, they simply show to what extent the basal value may actually be stimulated by the metabolic processes following the ingestion of pure or nearly pure carbohydrates. The time at which the maximum effect appears is likewise of great importance. An examination of the figures given in the last column shows that in all but a few instances the highest value appeared in the first 2 hours. The most notable exceptions to this are the experiments 198 FOOD INGESTION AND ENERGY TRANSFORMATIONS. with Dr. R., February 21, 1907, with the maltose-dextrose mixture; H. R. D., April 21, 1906, with bananas and sugar; and A. H. M., April 10, 1907, with popcorn. The general conclusions from this series of calorimeter experiments would therefore be that the ingestion of pure or nearly pure carbohy- drate produces a positive increase in the metabolism which for short periods, at least, may amount to almost 35 per cent, and that this increase nearly always takes place in the first 2 hours of experimenta- tion. An examination of tables 101 to 122 shows clearly that results obtained in the periods subsequent to the first 2 hours of the experi- ment give very little, if any, evidence as to the nature of the metab- olism, save that a persistent increase in the carbon-dioxide production is usually found. It is of particular significance, however, that in the majority of the experiments direct calorimetry shows definitely an increment in the heat production due to the ingestion of carbohydrates ; we can therefore consider this fact as established. The value of this known fact will be more apparent when an analysis is attempted of the intermediary processes involved in the metabolism of carbohydrate. On the other hand, we are not able from these calorimeter experi- ments to determine with great exactness the time relations between the ingestion of carbohydrate and the metabolism. While they bring out the fact that the maximum effect of carbohydrate ingestion appears in the first 2 hours and that thereafter practically no effect is noted in the majority of instances save in the production of carbon dioxide, experiments made with shorter periods are absolutely essential for a more careful analysis of the relationship. For these determinations in shorter periods recourse must be had to the long series of obser- vations in the respiration experiments with carbohydrates, from which an estimation may be made by indirect calorimetry of the course of the metabolism after carbohydrate ingestion. TOTAL INCREMENTS IN METABOLISM AFTER CARBOHYDRATE INGESTION (DIRECT CALORIMETRY). The discussion thus far has dealt primarily with the extent to which the basal metabolism may be increased temporarily by the ingestion of varying amounts of carbohydrates and the time relations between the maximum increase and the time of ingestion. As a casual exam- ination of tables 101 to 122 will show, the increase in the heat pro- duction after carbohydrate ingestion is, for the most part, only found in the first hour or two. In a number of the experiments the increment continues longer than the first period; it is thus important to note not simply the highest point to which the basal metabolism may be lifted by the ingestion of carbohydrate, but likewise the total effect of the carbohydrate upon the basal metabolism. This can be done only by INGESTION OF CARBOHYDRATES. 199 noting the total increment in the heat production. This increment is secured by measuring the total heat produced during the whole experi- ment and computing from the basal heat production the increment actually obtained in this period. The values found in the calorimeter experiments for the total increment in heat production after the ingestion of carbohydrate are given in table 124; in the last column of this table are also recorded the percentages of the total increments in terms of the basal value. The values for the basal heat production are included for purposes of comparison. TABLE 124.— Total increment in heat production following ingestion of carbohydrate. (Calorimeter experiments.) Carbohydrate. Amount. Subject. Date. Length of obser- va- tion.1 Heat measured in period of observation. Basal value. Increment above basal value. Total amount. Per cent. Sucrose Maltose-dextrose mixture (/rams. 191 2100 2100 80 458 431 307 299 =145 1,173\ 103 ( 1,1711 Km 1,1211 86] 7651 99[ 7i;:; 99!" IJ4S 77J 6111 of 403 400 397 199 187 6.32 A. H. M.. F. M. M . F. M. M . A. W. W . Dr. R... E. H. B.. A. H. M. . A. L. L... J. J. C. . . H. R. D.. H. R. D.. A. H. M.. A. L. L. . . A. L. L... J. J. C. . . F. M. M. Dr. H.... F. M. M . Dr. H.... A. H. M.. H. B. W.. A. L. L. . . Apr. 1, 1907 Jan. 31, 1910 Feb. 2, 1910 May 28, 1907 Feb. 21, 1907 May 14, 1907 Mar. 28, 1907 May 13, 1907 Mar. 4, 1910 Mar. 31, 1906 Apr. 21, 1906 Apr. 2, 1906 Mar. 30, 1906 Apr. 19, 1906 Apr. 7, 1909 Apr. 8, 1909 Feb. 14, 1910 Feb. 8, 1910 Feb. 17, 1910 Apr. 10, 1907 Apr. 9, 1907 May 27, 1907 hours. 8 5 4 4 8 8 8 8 4 8 10 8 8 12 4 3 3 4 4 8 8 8 ca/.s. 656 400 312 312 584 716 656 632 296 584 730 568 580 888 288 237 198 328 268 656 632 632 cals. 68 19 16 6 74 39 94 40 41 107 137 94 88 72 69 19 27 -2 21 66 39 7 10 5 5 2 13 5 14 6 14 18 19 17 15 8 24 8 14 -1 8 10 6 1 Bananas and sugar: Bananas . ... Sugar . Bananas Sugar. . ... Bananas Sugar . . Bananas Sugar Bananas Sugar Bananas Sugar. ... . . Bananas Sugar Bananas Popcorn Rice ... 'The time given represents the experimental period. The food was usually taken leas than half an hour before the beginning of the experiment. See tables 101 to 122 for details. 2Also juice of one lemon. 200 FOOD INGESTION AND ENERGY TRANSFORMATIONS. It is very difficult to obtain a satisfactory method for computing the percentage increment. Obviously the lengthening of the period in which the measurements are made without an increment above the basal metabolism simply increases the denominator of the fraction and thus increases the basal value without affecting the increment. The value of the increment in terms of per cent is thus decreased. In table 123 it will be seen that the percentage for the greatest increment above the basal value is in every instance considerably higher than the percentage for the total increment given in the last column of table 124. This is due in large part to the fact that the total increment in the heat production took place during the first hour or tAvo, while in the subse- quent hours the metabolism was essentially the same as the basal value. When the duration of the experiment is 12 hours instead of 4, 5, or 8 hours, as the case may be, the percentage total increment is naturally greatly decreased. A striking illustration of this is shown by com- paring the experiments with A. L. L., on March 30, 1906, and April 19, 1906, in wrhich essentially the same amounts of bananas and sugar were given. The greatest increment was 34 per cent in one case and 31 per cent in the other; in both experiments this increment occurred in some part of the first or second hour. The total increment above the basal value was found to be 88 calories in one case and 72 calories in the other. There was, however, a difference in the basal values of the two experiments of over 300 calories, owing to the fact that in the April experiment the length of the experimental period was 12 hours, while in the March experiment it was only 8 hours. The percentage increment in the March experiment was therefore nearly double that in the April experiment, while in other experiments the values are fairly good duplicates. The computation of the total increment above the basal value for ex- periments in which food was ingested is justifiable. The computation of the percentage of the increment is, however, open to serious criti- cism, and it is difficult to see how such percentages can have real sig- nificance. Yet they are frequently computed and reported in experi- ments of this kind. Perhaps their greatest value for this discussion is the fact that \vhile in these observations the experimental period varied in length only from 3 to 12 hours, and usually from 4 to 8 hours, it can readily be seen that were the remainder of the 24 hours added to the experimental period, the percentage value would be greatly decreased and, in fact, would nearly disappear. It can easily be under- stood, therefore, why investigators employing the 24-hour period have failed to note a material increase in the metabolism due to the ingestion of carbohydrates, for although there is a distinct temporary increase, which may at times reach 30 per cent or over, this increase, when com- pared to the total 24-hour basal value, appears almost insignificant. If, on the contrary, we are dealing with a substance which is delayed INGESTION OF CARBOHYDRATES. 201 in effect, even though its intensity may not be so great as that noted in some of our experiments, the use of the base-line for the longer period would be more justifiable and more truly indicative of the actual con- ditions than a base-line for a short period. Accordingly, while the values given in table 123 for the greatest increment above the basal metabolism may not be taken as indicating a prolonged effect at this level of intensity and should only be interpreted as the possible maxi- mum level to which the basal value may be raised, the percentage values in table 124 must be interpreted by taking into consideration simultaneously not only the total amount of increment measured but the basal value and particularly the length of the experimental period. As uniformity in results may not be expected with experiments of different length, these percentage values can have but little relative mathematical significance other than to explain the low values noted by investigators during 24-hour periods when carbohydrates are given. Although the experiments with pure carbohydrates are better adapted for comparison purposes than those with mixed carbohydrates, the discussion of the total increments in the metabolism as a result of the ingestion of the former will be deferred until the results of the respiration experiments are considered, as by far the larger number of experiments with the pure carbohydrates were made with the respiration apparatus. Still it is of significance to note from table 124 that with sucrose the total increment above the basal value for the entire period of measurement was 10 per cent in one case, and with the maltose-dextrose mixture it was 14 per cent in two cases. The percentages for the total increment above the basal value as computed for the mixed carbohydrates are likewise shown in table 124. The starch as ingested in the experiments with mixed carbohydrates was in three forms: first, in popcorn, which was dry and hence must undergo the process of imbibition in the stomach; second, in rice, which was cooked; and third, in the moist starch of bananas. The popcorn experiments were primarily designed to throw some light upon the ingestion of roughage in the diet and those with rice to give the effect of cooked starch. The effect of uncooked starch was studied with bananas, of which large amounts could be eaten with considerable ease. As carried out, however, the experimental method was some- what faulty in that the bananas were given, in all but three experi- ments, with relatively large amounts of cane sugar; hence we have unquestionably a double influence upon the metabolism. Total increments for bananas and sugar are frequently found of 17 to 24 per cent, showing very perceptibly the influence of the inges- tion of this mixture of carbohydrates. No great stress should be laid upon these computations, owing to the irregularities in the length of the observations and the fact that frequently the metabolism returned to the basal value before the experiment ended. Nevertheless, the gen- 202 FOOD INGESTION AND ENERGY TRANSFORMATIONS. eral picture shown for bananas and sugar is that of a very pronounced increase in heat production following their ingestion, which may rise in individual periods to a peak of 34 per cent, with a total increment above the basal value as high as 24 per cent and frequently 15 or more per cent, values which are considerably above those normally noted with pure carbohydrates. The effect following the ingestion of cane sugar is very pronounced; a considerable effect is likewise found with bananas. The high values obtained with the combined bananas and sugar point definitely to the conclusion that we have here an effect due to cane sugar which is superimposed upon the effect due to the large amount of carbohydrate taken simultaneously in the form of fruit. The experiments with bananas without sugar gave results which are irregular; two showed a measurable increment, while in the other no increment was obtained. The two experiments with popcorn indicate a distinctly higher metabolism as a result of the ingestion of this material. But one experiment was made with rice, a fact which is to be regretted, since the slight increment noted, namely, 7 calories, should be confirmed. It is evident that our section of this research dealing with carbohydrates of a gross texture and the possible effect of roughage in the diet is altogether too limited for adequate discussion. RESPIRATION EXPERIMENTS. As the research on the influence of the ingestion of food progressed, it became evident that measurements of the metabolism in short periods were essential, for many of the experiments indicated a some- what rapid change in the character of the metabolism following the ingestion of carbohydrate. Experiments with periods of sufficiently short duration to show this rapid change were impracticable with an apparatus so large as the respiration calorimeter in Middletown. With the development and subsequent completion in the Nutrition Laboratory of the so-called "universal respiration apparatus"1 observa- tions could readily be made in short periods with fairly satisfactory results. An extended series of such experiments was begun in the fall of 1910 and continued at intervals for several years. We are indebted to Mr. H. L. Higgins2 and Mr. L. E. Emmes for their kind coope- ration, as the majority of the experiments made in 1911 were under their immediate supervision. The experiments previous to 1912 were made with the so-called "tension-equalizer" form of the respiration apparatus,3 which was later replaced by the spirometer type of the same apparatus. Both types of the apparatus have been carefully 'This apparatus is described in detail by Benedict, Deutsch. Arch. f. klin. Med., 1912, 107, pp. 156-200; also Carpenter, Carnegie Inst. Wash. Pub. No. 216, 1915, pp. 21-53. 'See, also, Higgins, Am. Journ. Physiol., 1916, 41, p. 258. 'Carpenter, Carnegie Inst. Wash. Pub. No. 216, 1915, p. 21, and Benedict, Am. Journ. Physiol., 1909, 24, p. 345. INGESTION OF CARBOHYDRATES. 203 tested by one of us1 and their capacity for yielding accurate results has been proved. The universal respiration apparatus measures both the carbon- dioxide excretion and the oxygen consumption, and special records are made of the pulse rate and the respiration rate. The spirometer form of the apparatus also gives a record of the ventilation of the lungs. Although the heat production is not measured by this apparatus, it has been computed by the indirect method from the measurements of the oxygen consumption by means of the factors for non-protein quo- tients of Zuntz and Schumburg.2 It should be stated that in this computation no correction was made for the heat resulting from the combustion of protein and the actual non-protein quotients were not TABLE 125. — Comparison of values for heat as computed until observed and non-protein quotients. (Values per minute.) K. H. A., May 18, 1912.1 P. F. J., May 22, 1912.1 Respiratory quotient. Heat. Respiratory quotient. Heat, Observed. Non- protein. Un cor- rected. Corrected for protein. Observed. Non- protein. Uncor- rected. Corrected for protein. cals. cats. cals. cals. 0.822 0.832 1.052 1.032 0.912 0.932 1.122 1.102 .94 .99 1.24 1.22 1.07 1.12 1.16 1.13 1.00 1.08 1.19 1.15 1.11 1.16 1.20 1.18 .97 1.03 1.20 1.17 1.03 1.07 1.24 1.22 .92 .97 1.12 1.10 1.00 1.04 1.24 1.21 .91 .95 1.07 1.04 .96 .99 1.23 1.22 .86 .88 1.03 1.01 .93 .96 1.12 1.11 'See tables 140 and 145, pp. 212 and 213. Diet: 100 grams levulose, with juice of one lemon. 2Basal value; average of 3 periods. computed. Magnus-Levy3 has shown that only a slight error of approximately 3 per cent results from neglecting to compute the pro- tein metabolism in indirect calorimetry. The small variations due to the use of the determined quotients in our computations are illustrated by the comparison made in table 125. It has therefore not seemed justifiable to recompute the heat values on the basis of the non-protein respiratory quotient, especially as the results had only a differential significance in this study and the increment above the basal value was the special object of the computations. In most cases, the respira- tory quotients as determined are but 2 to 5 points lower than the non- protein respiratory quotients. With the high-nitrogen diets, the dif- ferences are even smaller. 'Carpenter, Carnegie Inst. Wash. Pub. No. 216, 1915, pp. Ill and 227. JZuntz and Schumburg, Physiologie des Marsches, 1901, p. 361. 'See Loewy, Oppenheimer's Handbuch der Biochemie, 1911, 4 (1), p. 281; also Magnus-Levy, von Noorden's Handbuch der Pathologic des Stoffwechsels, 1896, 1, p. 207. 204 FOOD INGESTION AND ENERGY TRANSFORMATIONS. In practically all of the observations with the respiration apparatus, the basal value was determined each day just prior to the ingestion of the carbohydrate studied, usually as a result of 2 to 4 well-agreeing periods. From the results obtained with the calorimeter experiments, it was clear that a greatly increased production of carbon dioxide was to be expected after the ingestion of the carbohydrate and that this might persist for some time, but that the increase in the oxygen con- sumption would probably not continue for a great length of time. Hence most of our respiration experiments were terminated 3 to 4 hours after the ingestion of the carbohydrate; occasionally some experiments were even shorter than this. In no instance were the experiments continued for 8 hours, as was frequently the case in the calorimeter experiments. The periods were usually 15 minutes long, but in one or two experiments they were much shortened for the pur- pose of studying the rapid fluctuations in the respiratory quotient.1 Only pure carbohydrates were used in the respiration experiments, i. e., dextrose, levulose, sucrose, and lactose. These carbohydrates may be considered as chemically pure products, save that levulose and lactose contain a small percentage of water.2 The amounts given were in practically every experiment either 100 or 75 grams. In many of the experiments the sugars were taken in solution, water and varying amounts of lemon juice being added. As a rule, the juice of one-half or a whole lemon was used, this being approximately 20 or 40 grams. A large number of subjects were studied and sufficient data secured to draw general deductions, but it should be borne in mind that the individual values must not be considered as indicative of the indi- viduality of the subject or of any particular abnormality. With the universal respiration apparatus, duplicate gas analyses are not made; the measurements of the carbon-dioxide production and oxygen con- sumption for each period therefore represent only individual determin- ations. This fact should be especially emphasized, as with practically all other forms of respiration apparatus duplicate gas analyses are the rule. STATISTICS OF RESPIRATION EXPERIMENTS. With so large a number of respiration experiments, it seems needless to discuss them individually; hence only the statistical data are given here, grouped according to the carbohydrate used, with the idea of including the results later in general summary tables and discussing not only the influence of the individual carbohydrates upon the basal metabolism, but likewise the effect of variations in the amounts in- gested. The preliminary experiments with the universal respiration apparatus on the influence of the ingestion of food were made with the 1See, for instance, tables 134 and 146, pp. 209 and 214. 2The levulose contained 4.8 per cent moisture; lactose having one molecule of crystallization was always used. INGESTION OF CARBOHYDRATES. 205 cooperation of Professor Otto Cohnheim, formerly of Heidelberg, who kindly volunteered as a subject while he was a guest of the Nutrition Laboratory in the fall of 1909. The details of the experiments with Professor Cohnheim are given in tables 154 and 155. The details of the whole series of respiration experiments following the ingestion of carbohydrates are given in tables 126 to 168. Statistical data not included in the tables are given in the following pages for a number of the experiments. When no further data are available, no mention is made of the experiment in the statistical text. DEXTROSE EXPERIMENTS. J. J. C., 9h47m a. m. to 4h05m p. m., March 7, 1911. 64.2 kilograms.- Very quiet in first basal period, probably slept a little; marked tendency to fall asleep in second period; in second, third, and sixth food periods, necessary for observer to speak to the subject often to prevent his falling asleep; in last food period, jumped violently once when aroused. Nitrogen in urine per hour 7h15m a. m. to 4h35m p. m., 0.30 gram. L. E. E., 8h33m a. m. to 3hoom p. m., May 29, 1911. 59.2 kilograms.— Very quiet in first basal period; asleep a few moments before end of third period; somewhat restless in fourth basal period. Asleep a few moments in first and third food periods, also slept during intermissions between second and third food periods and between third and fourth food periods. Nitrogen in urine per hour 7h40m a. m. to Ilh08ra a. m., 0.46 gram; Ilh08m a. m. to 12h57m p. m., 0.53 gram; 12h57m p. m. to 4h06m p. m., 0.31 gram. C. H. H., 9h12m a. m. to 4h51m p. m., May 1, 1911. 55.5 kilograms. Very quiet and awake all periods; complained of nausea after taking dextrose. Nitrogen in urine per hour 7 a. m. to 5h03m p. m., 0.32 gram. H. L. H., 8h40m a. m. to 3h54m p. m., May 24, 1911. 59.8 kilograms.— Very quiet and awake in basal periods; after taking dextrose, also very quiet and awake; very warm in seventh food period and asked to have electric fan set in motion. Nitrogen in urine per hour 7h35m a. m. to Ilh30m a. m., 0.53 gram; Ilh30m a. m. to 3h20m p. m., 0.44 gram. P. F. J., 8h46m a. m. to 2 p. m., May 15, 1912. 56.8 kilograms.— Consid- erable movement between first and second food periods, also between third and fourth food periods. Nitrogen in urine per hour 7h30m a. m. to 2h05m p. m., 0.49 gram. J. J. C., Ilh04m a. m. to 2h24m p. m., December 22, 1910. 64.7 kilograms.— High-carbohydrate diet on previous day. Sat down at 10h47m a. m. in com- fortable Morris chair, with foot-rest. Adhesive plaster used to secure perfect closure of mouth. In first basal period wide awake, but more sleepy as experi- ment continued; very sleepy in fourth basal period. After dextrose, awake all of first period but inclined to be drowsy near end; drowsiness increased in second food period; very sleepy in third food period; went to sleep in fourth food period, while observer was talking to him; occasional slight movements in sleep. Was cold at beginning of first food period and used blanket most of experiment. Nitrogen in urine per hour 8h15m a. m. to 2h33m p. m., 0.44 gram. J. J. C., 9h05m a. m. to 5h29m p. m., December 28, 1910. 64.7 kilograms.- High-carbohydrate diet preceding day. Wooden head-rest used in experiment. Slept most of time in second and third basal periods, probably awake in last basal period. Slept most of third, fourth, and fifth food periods; no attempt made to keep him awake in fourth and fifth periods; probably awake in first and sixth food periods; very wide awake in seventh food period. Some pain 206 FOOD INGESTION AND ENERGY TRANSFORMATIONS. in stomach as a resultof taking dextrose. Nitrogen in urine per hour 8h10ra a. m. to 5h32m p. m., 0.40 gram. V. G., 10*54m a- w. to 4h14m p. m., December 23, 1910. 55.1 kilograms.- Subject sitting in chair during experiment. Awake throughout basal periods; very restless in second basal, frequently looking at clock; very quiet in third basal period. Awake throughout food periods except in fourth, when he slept a little; very quiet in fifth period; after fifth and sixth food periods complained of difficulty in breathing through one nostril, also that left nostril was sore ; allowed to rest a half hour between sixth and seventh food periods and asked to free his nose from all mucus before last period began. Nitrogen in urine per hour 7h20m a. m. to 4h33m p. m., 0.33 gram. V. G., 9h02m a. m. to 3h04m p. m., December 29, 1910. 55.7 kilograms. High-carbohydrate diet on preceding day. Basal periods, awake in first period, much more sleepy in second, slept some in third, slight movement in fourth, absolutely quiet and awake in fifth period. After dextrose, sleepy in first period and possibly slept a little; awake and restless in third period, especially towards the end, drawing deep breaths; left nostril seemed clogged. Nitrogen in urine per hour 7h50m a. m. to 5h25m p. m., 0.36 gram. TABLE 126. — K. H. A., May 14, 1912. Lying. (Values per minute.) Dextrose: Amounts, 100 grams dextrose, juice of one lemon; energy, 385 cals.; from carbohydrates, 100 p. ct. Time. Ventila- tion (reduced) . Average respiration rate. Carbon dioxide. Respira- tory quotient. Oxygen. Average pulse rate. Heat (com- puted). Without food: Av. of 3 periods . With food:1 10h20ma.m liters. 5.19 4.89 14.4 14.0 c.c. 187 183 0.84 .85 c.c. 223 216 55 49 cals. 1.08 1.05 10 55 a.m 6 12 14 3 235 98 240 60 1.21 11 34 a.m 6 12 15 4 232 1 01 230 61 1.16 12 02 p.m 5.62 14.8 214 1.00 214 55 1.08 1 25 p.m 1 51 p.m 5.85 5.30 14.9 11.8 225 210 1.00 .89 224 235 61 57 1.13 1.15 Subject drank dextrose and lemon juice in 325 c.c. of water at 10h01m a. m. TABLE 127. — J. C. C., December 31, 1912. Lying. (Values per minute.) Dextrose: Amounts, 100 grams dextrose, juice of half lemon ; energy, 380 cals. ; from carbohydrates, 100 p. ct. Time. Ventila- tion (reduced). Average respiration rate. Carbon dioxide. Respira- tory quotient. Oxygen. Average pulse rate. Heat (com- puted). Without food : Av. of 3 periods . With food:1 Ilh13ma.m liters. 5.41 5.48 12.6 12.2 c.c. 187 196 0.74 .72 c.c. 252 272 62 78 cals. 1.19 1.28 11 45 a.m 5.54 13.0 203 .77 264 71 1.26 12 17 p.m 5.68 13.3 208 .78 268 66 1.28 12 50 p.m 5 61 12 4 210 .78 269 65 1.28 1 32 p.m 5 42 12 3 205 .81 253 64 1.22 211 p.m 5 48 13 4 200 .81 247 63 1.19 3 04 p.m 5 36 14 9 178 .72 246 63 1.16 'Subject drank dextrose and lemon juice in 250 c.c. of water nt Ilb05m a. m. INGESTION OF CARBOHYDRATES. 207 TABLE 128. — J. J. C., March 7, 1911. Lying. (Values per minute.) Dextrose: Amounts, 100 grams dextrose, juice of half lemon; energy, 380 cals. ; from carbohy- drates, 100 p. ct. Time. Average respiration rate. Carbon dioxide. Respiratory quotient. Oxygen. Average pulse rate. Heat (computed). Without food: Av. of 4 periods . . With food i1 12b21mp.m 16 17 c.c. 184 215 0.79 .79 c.c. 232 272 59 67 cals. 1.11 1.30 1 12 p.m 16 242 .89 271 66 1.33 1 48 p.m 15 240 .90 268 68 1.32 2 24 p.m 16 239 .92 261 68 1.29 2 56 p.m . . 18 222 .94 236 68 1.17 3 50 p.m 18 217 68 1.19 'Subject drank dextrose and lemon juice in 200 c.c. of water at 12h08m p. m. TABLE 129. — L. E. E., May 29, 1911. Lying. (Values per minute.) Dextrose: Amounts, 100 grams dextrose, juice of half lemon; energy, 380 cals.; from carbohy- drates, 100 p. ct. Time. Average respiration rate. Carbon dioxide. Respiratory quotient. Oxygen. Average pulse rate. Heat (computed). Without food : Av. of 4 periods. . With food :l 10h48ma.m 11 27 a.m 13 14 14 c.c. 183 195 219 0.78 .82 .88 c.c. 236 237 250 57 55 60 cals. 1.13 1.14 1 23 12 01 p.m 16 230 92 251 57 1.24 12 33 p.m 16 232 91 255 57 1 26 1 30 p.m. 16 237 96 246 62 1.23 2 10 p.m. 17 206 91 227 59 1 12 2 67 p.m 15 203 .80 254 57 1.22 3 40 p.m 14 203 59 Subject drank solution (325 c.c.) at 10h32m a. m. TABLE 130. — C. H. H., May 1, 1911. Lying. (Values per minute.) Dextrose: Amounts, 100 grams dextrose, juice of half lemon ; energy, 380 cals. ; from carbohy- drates, 100 p. ct. Time. Average respiration rate. Carbon dioxide. Respiratory quotient. Oxygen. Average pulse rate. Heat (computed). Without food : Av. of 3 periods . . With food :l Ilh21ma.m . 14 12 c.c. 167 197 0.87 85 c.c. 193 231 60 73 cals. 0.94 1 12 11 50 a.m 13 203 91 224 63 1.11 12 22 p.m 12 186 93 200 66 99 12 54 p.m 14 193 94 205 66 1.02 1 23 p.m 14 175 82 214 62 1.03 2 05 p.m 14 179 90 198 60 .97 3 50 p.m . . 15 180 93 194 61 .96 4 36 p.m .... 15 177 87 204 63 1.00 'Subject drank solution (325 c.c.) at 10h45m a. m. 208 FOOD INGESTION AND ENERGY TRANSFORMATIONS. TABLE 131. — H. L. H., May %4, 1911. Lying. (Values per minute.) Dextrose: Amounts, 100 grams dextrose, juice of half lemon; energy, 380 cals.; from carbohy- drates, 100 p. ct. Time. Average respiration rate. Carbon dioxide. Respiratory quotient. Oxygen. Average pulse rate. Heat (computed). Without food: Av. of 4 periods . . With food:1 llhllma.m 13 15 c.c. 183 189 0.82 78 c.c. 224 243 56 64 cals. 1.08 1 16 11 53 a.m 15 230 91 252 64 1 24 12 30 p.m. . . 16 219 94 233 63 1 16 1 01 p.m 15 222 98 227 65 1 14 1 42 p.m ... 16 215 94 228 62 1 13 2 21 p.m. 15 210 94 223 64 1 11 2 55 p.m 15 222 88 252 71 1 23 3 39 p.m 14 205 80 256 62 1 23 Subject drank solution (325 c.c.) at 10h55m a. m. TABLE 132. — P. F. J., May 15, 1912. Lying. (Values per minute.) Dextrose: Amounts, 100 grams dextrose, juice of one lemon; energy, 385 cals.; from carbohy- drates, 100 p. ct. Time. Ventila- tion (reduced). Average respiration rate. Carbon dioxide. Respira- tory quotient. Oxygen. Average pulse rate. Heat (com- puted). Without food: Av. of 3 periods . With food:1 10h44ma.m liters. 4.65 5.36 7.5 10 4 c.c. 200 219 0.84 89 c.c. 238 245 73 73 cals. 1.15 1 20 11 17 a.m 5.41 12.5 216 .91 237 69 1.17 12 05 p.m 5.20 7.9 225 .97 232 68 1.16 12 37 p.m 5.46 8.4 239 99 242 70 1.22 1 06 p.m 5.46 9 3 228 99 230 70 1.16 1 45 p.m 5.10 9.5 207 .87 238 75 1.16 'Subject drank dextrose and lemon juice in 325 c.c. of water at 10h05m a. m. TABLE 133. — B. M. K., December 30, 1912. Lying. (Values per minute.) Dextrose: Amount, 100 grams; energy, 374 cals.; from carbohydrates, 100 p. ct. Time. Ventila- tion (reduced) . Average respiration rate. ( 'arbon dioxide. Respira- tory quotient. Oxygen. Average pulse rate. Heat (com- puted). Without food: Av. of 4 periods . With food:1 Ilh12ma.m liters. 4.99 4.83 16.3 17 5 c.c. 152 156 0.70 .67 c.c. 217 233 71 79 cal*. 1.02 1 09 11 63 a.m 5.50 17.4 173 .73 236 83 1.11 1 19 p.m 5.70 17.5 188 .77 243 82 1.16 2 00 p.m 5.57 17.7 181 .79 228 79 1.09 2 64 p.m 5.11 16.8 166 .76 219 72 1.04 3 47 p.m 5.06 17.8 154 .72 214 71 1.01 Subject drank dextrose in 250 c.c. of water at Ilh02m a. m. INGESTION OF CARBOHYDRATES. 209 TABLE 134.— .4. J . 0., December 11, 1914- Lying. (Values per minute.) Dextrose: Amount, 100 grains; energy, 374 cals. ; from carbohydrates, 100 p. ct. Time. Ventila- tion (reduced) . Average respiration rate. Carbon dioxide. Respira- tory quotient. Oxygen. Average pulse rate. Heat (com- puted). Without food : Av. of 3 periods. With food:1 10h29™a.m liters. 6.96 7.12 22.1 21.3 c.c. 220 234 0.87 .91 c.c. 253 258 61 cala. 1.24 1.27 10 32 a.m . . . 7.22 22.0 239 .85 280 1.36 10 35 a.m. . 6 77 21.6 223 .87 257 1.26 10 40 a.m 6.83 21.0 223 .87 258 1.26 10 45 a.m 6.97 21.0 234 .90 261 1.29 10 50 a.m 7.23 21.4 243 .91 267 1.32 1 1 05 a.m 7.71 21.9 269 .94 287 69 1.43 11 44 a.m 8.29 21.5 297 .96 308 66 1.54 'Subject drank mixture (about 300 c.c.) of dextrose and cereal coffee at 10h26m a. m. 1 gram of the preparation per 200 c.c. was used for the cereal coffee. About A ui.uu \JL LJUG picpaiatiuu |jci &\j\j \j.\j. wc*o uocu IV;A tiic vcical < TABLE 135. — Dr. P. R., May 3, 1912. Lying. (Values per minute.) Dextrose: Amounts, 100 grams dextrose, juice of one lemon; energy, 385 cals. ; from carbohydrates. 100 p. ct. Time. Ventila- tion (reduced) . Average respiration rate. Carbon dioxide. Respira- tory quotient. Oxygen. Average pulse rate. Heat (com- puted) . Without food: Av. of 3 periods . With food:1 ll''02ma.m liters. 4.29 4 45 14.0 14 8 c.c. 146 150 0.78 76 c.c. 186 198 53 53 cala. 0.89 .94 11 24 a.m 4.71 16.2 161 .83 194 55 .94 11 43 a.m 5.09 17.2 177 .91 194 57 .96 12 25 p.m 5.07 16.6 173 .86 202 56 .98 12 57 p.m 4.93 15.9 175 .87 202 58 .99 1 42 p.m 5.04 16.2 174 .87 201 59 .98 2 32 p.m 5.00 17.2 171 .89 192 57 .94 3 12 p.m 4.99 16.5 167 .90 186 57 .92 Subject drank dextrose and lemon juice in 325 c.c. of water at 10h58m a. m. TABLE 136. — J. J. C., December 22, 1910. Silting. (Values per minute.) Dextrose: Amounts, 75 grams dextrose, juice of half lemon; energy, 286 cals.; from carbohydrates, 100 p. ct. Time. Average respiration rate. Carbon dioxide. Respiratory quotient. Oxygen. Average pulse rate. Heat (computed). Without food: Av. of 4 periods . With food:1 12b49mp.m 18 20 c.c. 193 203 0.88 .84 c.c. 220 242 59 62 cals. 1.08 1.17 1 16 p.m 19 221 .91 243 60 1.20 1 39 p.m 18 236 .93 254 60 1.26 2 09 p.m 17 232 59 1.24 Subject drank dextrose and lemon juice in 150 c.c. of water at 12h41m p. m. 210 FOOD INGESTION AND ENERGY TRANSFORMATIONS. TABLE 137. — J. J. C., December 28, 1910. Lying. (Values per minute.) Dtxtroae: Amounts, 75 grams dextrose, juice of one lemon; energy, 292 cals. ; from carbohydrates, 100 p. ct. Time. Average respiration rate. Carbon dioxide. Respiratory quotient. Oxygen. Average pulse rate. Heat (computed). Without food : Av. of 6 periods . . With food :l Ih01mp.m. . .. 18 17 c.c. 203 228 0.86 93 c.c. 235 244 69 71 cals. 1.15 1 21 141 p.m 16 230 98 235 68 1 18 2 17 p.m 16 248 98 253 71 1 27 3 00 p.m 18 217 94 230 65 1 14 3 28 p.m 17 216 94 231 68 1 15 4 31 p.m. . 18 214 87 247 70 1 21 6 14 p.m . . . 21 215 80 270 75 1 30 'Subject drank dextrose and lemon juice in 150 c.c. of water at 12h25m p. m. TABLE 138. — V. G., December 23, 1910. Sitting. (Values per minute.) Dextrose: Amounts, 75 grams dextrose, juice of half lemon; energy, 286 cals.; from carbohydrates- 100 p. ct. Time. Average respiration rate. Carbon dioxide. Respiratory quotient. Oxygen. Average pulse rate. Heat (computed). Without food: Av. of 3 periods . . With food :l 12b25mp.m. . 18 19 c.c. 208 201 0.89 84 c.c. 233 240 60 57 cals. 1.14 1 16 12 54 p.m 20 210 88 239 56 1 17 1 22 p.m 20 232 86 269 60 1 31 2 08 p.m 19 235 .93 254 63 1.26 2 37 p.m 17 229 93 247 68 1.23 3 06 p.m . ... 17 238 96 249 67 1 24 4 00 p.m 20 219 .97 225 61 1.13 'Subject drank dextrose and lemon juice in 150 c.c. of water at 12h15m p. m. TABLE 139. — V. G., December 29, 1910. Lying. (Values per minute.) Dextrose: Amounts, 75 grams dextrose, juice of one lemon; energy, 292 cals. ; from carbohydrates 100 p. ct. Time. Average respiration rate. Carbon dioxide. Respiratory quotient. Oxygen. Average pulse rate. Heat (computed). Without food: Av. of 5 periods . . With food:1 12h26mp.m 20 20 c.c. 214 231 0.90 91 c.c. 237 253 60 64 cals. 1.17 1.25 1 05 p.m 21 236 92 256 65 1.27 1 34 p.m 15 254 1 00 254 72 1.28 2 09 p.m 19 236 95 249 66 1.24 2 49 p.m 20 249 1 00 250 65 1 26 'Subject drank dextrose and lemon juice in 150 c.c. of water at 12b15m p. m. INGESTION OF CARBOHYDRATES. 211 LEVULOSE EXPERIMENTS. K. H. A., 8*29m a. w. to Ih33m p. m., May 18, 1912. 66.5 kilograms.— In first food period opened mouth once; in fourth food period pulse rate very irregular; possibly opened mouth in this period; adhesive plaster over mouth in succeeding periods. Nitrogen in urine per hour 7h55m a. m. to Ih55m p. m., 0.66 gram. J. P. C., 8h35m a. m. to 5h07m p. m., April 3, 1911. — In second basal period rubbed eyes with hand, also moved arms and legs. Chilly during third basal period; two blankets used; moved feet a little; slight movements in fourth basal period. In second food period, quiet and sleepy; coughed once in third food period ; lips found drawn away from mouthpiece. Nitrogen in urine per hour 7h45m a. m. to 12h25m p. m., 0.55 gram; 12h25m p. m. to 5h15mp. m., 0.30 gram. L. E. E., 8h37m a. m. to %h44m p. m., May 22, 1911. 59.4 kilograms.— Defecated between second and third food periods, also between fourth and fifth periods; cramps in stomach in fourth period. Nitrogen in urine per hour 7h45m a. m. to Ilh20m a. m., 0.43 gram; Ilh20m a. m. to 1 p. m., 0.30 gram; 1 p. m. to 3h10m p. m., 0.40 gram. C. H. H., 8h45m a. m. to Sh£lm p. m., May 16, 1911. 55.2 kilograms.— Very quiet during first basal and third food periods; in latter period was falling asleep as period ended; in fifth food period, moved slightly several times; difficult to keep feet still; flies annoyed him somewhat in seventh food period. Nitrogen in urine per hour 7 a. m. to 3h45ra p. m., 0.46 gram. H. L. H., 8h43m a. m. to 3hllm p. m., June 1, 1911. 60.5 kilograms.— In first basal period very quiet and awake. Between second and third food periods defecated and urinated; between third and fourth food periods, some- what restless; between fourth and fifth food periods left room to defecate. Nitrogen in urine per hour 8 a. m. to 10h55m a. m., 0.71 gram; 10h55m a. m. to 3h25m p. m., 0.54 gram. P. F. J., 8*4om a. m. to 2b08m p. m., May 22, 1912— 51 A kilograms— In second food period some nausea. Nitrogen in urine per hour 7h30m a. m. to 2h26m p. m., 0.39 gram. J. J. C., 8ho2m a. m. to 5h14m P- m., December 31, 1910. — High-carbohydrate diet on preceding day. Wooden framework used to keep head in position during experiment. Asleep most of first and second basal periods and in the intermission between these periods; also asleep in the intermission between first and second food periods and during second and fifth food periods; in sixth food period sleepy but moved slightly several times; awake throughout eighth and ninth food periods. Nitrogen in urine per hour 7 a. m. to 5h25m p. m., 0.25 gram. J. J. C., 3h06m p. m. to 5k07m p. m., January 4, 1911. 64.6 kilograms.— Awake throughout and quiet. Nitrogen in urine per hour 8 a. m. to 5h10m p. m., 0.37 gram. 212 FOOD INGESTION AND ENERGY TRANSFORMATIONS. TABLE 140. — K. H. A., May 18, 1912. Lying. (Values per minute.) Levulose: Amounts, 100 grams levulose, juice of one lemon; energy, 384 cals.; from carbohydrates, 100 p. ct. Time. Ventila- tion (reduced). Average respiration rate. Carbon dioxide. Respira- tory quotient. Oxygen. Average pulse rate. Heat (com- puted) . Without food : Av. of 3 periods . With food i1 10h15ma.m liters. 4.79 6.09 13.7 14.7 c.c. 179 235 0.82 .94 c.c. 218 249 48 44 cals. 1.05 1 24 10 50 a.m . 5.98 14 5 236 1 00 236 47 1 19 11 25 a.m . . 6 11 14 4 231 97 239 48 1 20 12 05 p.m 5 50 14 2 208 92 226 48 1 12 12 45 p.m 5.38 14.7 196 .91 216 45 1 07 1 18 p.m 5.04 14.5 182 .86 212 48 1 03 'Subject drank levulose and lemon juice in 325 c.c. of water at 9h55m (?) a. m. TABLE 141. — J. P. C., April 3, 1911. Lying. (Values per minute.) Levulose: Amounts, 100 grams levulose, juice of half lemon; energy, 379 cals.; from carbohy- drates, 100 p. ct. Time. Average respiration rate. Carbon dioxide. Respiratory quotient. Oxygen. Average pulse rate. Heat (computed). Without food: Av. of 5 periods . . With food:1 12h05mp.m 18 21 c.c. 185 240 0.85 1 01 c.c. 217 237 51 55 cola. 1.06 1 20 12 38 p.m 20 241 1 03 233 56 1 18 1 12 p.m 20 231 98 236 58 1 19 1 40 p.m l>0 24G 1 00 247 59 1 25 3 15 p.m 19 209 89 236 57 1 16 4 25 p.m . 19 19S 90 221 55 1 09 4 52 p.m L'f) 199 85 234 53 1 14 'Subject drank solution (345 c.c.) at Ilh43m a. in. TABLE 142.— L. E. E., May 22, 1911. Lying. (Values per minute.) Levulose: Amounts, 100 grams levulose, juice of half lemon; energy, 379 cals.; from carbohy- drates, 100 p. ct. Time. Average respiration rule. Carbon dioxide. Respiratory (jiiotiont. Oxygen. Average pulse rate. Heat (computed). Without food: Av. of 3 periods . . With food:1 10b05ma.m 12 14 c.c. 190 245 0.77 94 c.c. 248 262 60 57 cals. 1.18 1 30 10 59 a.m 12 263 98 269 60 1 35 11 63 a.m 15 246 '.)5 257 61 1 28 12 28 p.m 15 248 1 00 247 59 1 25 1 24 p.m 13 202 X9 227 57 1 12 1 57 p.m 11 189 82 231 57 1 11 2 28 p.m 15 186 .76 245 54 1 10 'Subject drank solution (325 c.c.) at 9hlSm a. in. INGESTION OF CARBOHYDRATES. 213 TABLE 143. — C. H. H., May 16, 1911. Lying. (Values per minute.) Levulose: Amounts, 100 grams levulose, juice of half lemon; energy, 379 cals. ; from carbohy- drates, 100 p. ct. Time. Average respiration rate. Carbon dioxide. Respiratory quotient. Oxygen. Average pulse rate. Heat (computed) . Without food: Av. of 2 periods . . With food:1 9h58ma.m 14 13 c.c. 177 204 0.88 .93 c.c. 201 220 61 59 cals. 0.98 1.09 10 32 a m 14 216 97 222 62 1.11 11 07 a.m 15 216 .97 222 64 1.11 11 44 a.m . ... 13 214 .94 227 65 1.13 12 23 p.m 1 10 p.m 13 15 198 221 .90 99 219 223 64 63 1.08 1.12 1 44 p.m 15 206 94 218 63 1.08 2 34 p.m 14 176 .85 207 59 1.01 3 06 p.m 15 178 .86 206 60 1.00 'Subject drank solution (325 c.c.) at 9h46m a. m. TABLE 144.— H. L. H., June 1, 1911. Lying. (Values per minute.) Lfvulose: Amounts, 100 grams levulose, juice of half lemon; energy, 379 cals.; from carbohy- drates, 100 p. ct. Time. Average respiration rate. Carbon dioxide. Respiratory quotient. Oxygen. Average pulse rate. Heat (computed). Without food: Av. of 2 periods . . With food:1 10h29ma.m 15 17 c.c. 197 259 0.83 1 02 c.c. 237 265 63 65 calt. 1.15 1 29 11 20 a.m . 16 247 98 251 66 1 26 12 04 p.m 14 249 1 00 250 65 I 26 12 40 p.m 16 222 .90 246 65 1 21 1 22 p.m 17 239 .96 248 66 1 24 2 14 p.m 20 211 .88 239 65 1 17 2 56 p.m 18 198 .82 242 61 1 17 Subject drank solution (325 c.c.) at 9h58m a. m. TABLE 145.— P. F. J., May 22, 1912. Lying. (Values per minute.) Levulose: Amounts, 100 grams levulose, juice of one lemon; energy, 384 cals.; from carbohydrates, 100 p. ct. Time. Ventila- tion (reduced). Average respiration rate. Carbon dioxide. Respira- tory quotient. Oxygen. Average pulse rate. Heat (com- puted). Without food: Av. of 3 periods . With food:1 10h26ma.m liters. 4.89 6 G5 8.6 16 4 c.c. 206 °45 0.91 1 07 c.c. 226 2°9 72 64 cals. 1.12 1 16 10 55 a.m 6 64 r> 9 263 1 11 238 71 1 20 11 32 a.m 6 33 11 7 253 1 03 246 so 1 24 12 25 p.m 5 65 10 4 246 1 00 245 74 1 24 1 03 p.m 6 01 10 0 237 96 247 74 1 23 1 53 p.m 5 46 11 1 211 93 226 70 1 12 'Subject drank levulose and lemon juice in 325 c.c. of water at H)h10m a. m. 214 FOOD INGESTION AND ENERGY TRANSFORMATIONS. TABLE 146. — A. J. 0., December 8, 1914. Lying. (Values per minute.) Levulose: Amount, 100 grams; energy, 373 cals. ; from carbohydrates, 100 p. ct. Time. Ventila- tion (reduced). Average respiration rate. Carbon dioxide. Respira- tory quotient. Oxygen. Average pulse rate. Heat (com- puted). Without food: Av. of 3 periods . With food:1 10h20ma.m liters. 6.92 6.69 23.0 22.0 c.c. 220 219 0.90 .96 c.c. 245 229 60 cala. 1.21 1 14 10 23 a.m 7.59 21.3 262 1.07 244 1 23 10 26 a.m 7.06 19.5 250 1 09 230 1 16 10 30 a.m 7.44 19.1 264 1 07 246 1 24 10 35 a.m 7.66 19.7 275 1 10 249 1 26 10 40 a.m . . 7.69 20 0 272 1.05 258 1 30 10 51 a.m 8.53 21 5 304 1 09 280 59 1 41 11 36 a.m 8.37 22.5 273 .98 279 64 1 40 'Subject drank mixture (about 300 c.c.) of levulose and cereal coffee at 10h15m a. m. About 1 gram of the preparation per 200 c.c. was used for the cereal coffee. TABLE 147. — J. J. C., December 31, 1910. Lying. (Values per minute.) Levulose: Amount, 75 grams.; energy, 280 cals.; from carbohydrates, 100 p. ct. Time. Average respiration rate. Carbon dioxide. Respiratory quotient. Oxygen. Average pulse rate. Heat (computed) . Without food: Av. of 3 periods . . With food:1 10h42ma.m 17 17 c.c. 200 262 0.91 1.10 c.c. 220 239 65 62 cala. 1.09 1.21 11 10 a.m 18 253 1.05 240 70 1.21 11 41 a.m 18 267 1.04 256 69 1.29 12 17 p.m 17 243 .99 246 74 1.24 12 49 p.m 17 232 .96 241 75 1 20 1 19 p.m . 16 228 .95 240 69 1 20 1 60 p.m 16 215 .93 230 67 1.14 2 33 p.m 18 221 .95 233 72 1.16 4 32 p.m 19 220 .98 225 66 1.13 5 00 p.m 20 211 .86 246 67 1.20 'Subject took levulose at lO^T™ a. m. TABLE 148. — J. J . C., January 4, 1911. Lying. (Values per minute.) Levulose: Amounts, 75 grams levulose, juice of one lemon; energy, 291 cals.; from carbohy- drates, 100 p. ct. Time. Average respiration rate. Carbon dioxide. Respiratory quotient. Oxygen. Average pulse rate. Heat (computed). Without food: c.c. c.c. cals. Av. of 2 periods . . 21 213 0.89 240 65 1.18 With food:1 4b04mp.m 20 270 1.04 260 71 1.31 4 30 p.m 20 276 1.05 262 64 1.32 4 52 p.m 20 272 1.01 269 69 1.36 'Subject drank levulose and lemon juice in 150 c.c. of water at 3b52m p. m. INGESTION OF CARBOHYDRATES. 215 SUCROSE EXPERIMENTS. H. H. A., 7h42m a. m. to 12h56m p. m., January 2, 1912.1 61.2 kilograms.— Urinated and defecated between fifth and sixth food periods, resting about 15 minutes afterward. Nitrogen in urine per hour 6h45m a. m. to 10h30m a. m., 0.33 gram; 10h30'n a. m. to Ilh50m a, m., 0.25 gram. L. E. E., 8h44m a. m. to 3h19m p. m., May 15, 1911. 60.3 kilograms.— Quiet throughout experiment with occasional slight movements; asleep in last two or three minutes of fourth food period. Defecated at 12h55m p. m. Nitrogen in urine per hour 8 a. m. to 10h05m a. m., 0.61 gram; 10h05m a. m. to 12h55m p. m., 0.48 gram; 12h55m p. m. to 3h30m p. m., 0.30 gram. A. F. G., 8h38m a. m. to 2h05m p. m., May 20, 1911. 53.9 kilograms.— Lay down on couch at 8 a. m. after drinking a glass of water. Quiet in first and second basal periods ; in first food period somewhat nervous and apprehensive. In third food period, there seemed to be a leakage of air, but it was not located. Nitrogen in urine per hour 6h30m a. m. to 10h56m a. m., 0.36 gram; 10h56m a. m. to 2h30m p. m., 0.48 gram. C. H. H., 8*42m a. m. to 2*25m p. m., May 10, 1911. 55.5 kilograms.— Awake and quiet throughout experiment; much more wide awake in last period than in preceding. Found it difficult to take full amount of sucrose. Nitrogen in urine per hour 7 a. m. to 12h12m p. m., 0.34 gram; 12h12m p. m. to 2h40m p. m. 0.68 gram. H. L. H., 8h31m a. m. to 2*2 lm p. m., May 17, 1911. 59.9 kilograms.— Quiet and awake throughout experiment; in first basal period had difficulty in breathing due to a cold; larger nosepieces were given him before second basal period, which enabled him to breathe more easily, although nosepieces gave him more or less discomfort owing to soreness of nostrils due to cold. In second food period pulse rate high, probably due to fact that visitors were expected. Nitrogen in urine per hour 10h52ra a. m. to 2h52m p. m., 0.43 gram. Professor C., 8h46m a. m. to ll*35m a. m., November 20, 1909. 83.0 kilo- grams.— First food period only 10 minutes long. Defecated at 10h15m a. m. Nitrogen in urine per hour 10h15ra a. m. to Ilh35m a. m., 0.79 gram. Professor C., 8h37m a m. to 2*42™ p. m., November 22, 1909. 83.0 kilo- grams.— First food period 10 minutes long; intermission between basal and food periods, 3 hours and 51 minutes. During intermission went on roof of laboratory; sat there from 9h45m a. m. to Ilh15m a. m., without coat and part of time without vest; temperature of air 6.9° C.; a little rain; sugar and coffee taken after exposure to cold. Time between return from roof and beginning of first food period 2 hours and 10 minutes; lay on couch much of this time and a series of three observations were made not included in this record. Between first and second food periods and in third food period, nervous and restless. Nitrogen in urine per hour 7h40m a. m. to Ilh15m a. m., 0.65 gram. A. J. 0., 9h07m a. m. to ll*57m a. m., December 29, 1914. 70.0 kilograms.— Length of periods irregular, ranging from 3 to 10 minutes. Nitrogen in urine per hour, 8 a. m. to 12h20m p. m., 0.69 gram. J. J. C., Iho3m p. m. to 5*2Sm p. m., November 22, 1910. 64.3 kilograms. — high-carbohydrate diet on preceding day. Quiet throughout basal periods, very quiet in second basal period ; slept between second and third periods and in third basal period was kept awake with difficulty. In third basal period, lower lip dropped sufficiently to show the teeth; adhesive plaster was used over mouth in succeeding periods. So sleepy in last basal and in all food periods that constant attention of observer was required to keep him awake; Benedict and Joslin, Carnegie Inat. Wash. Pub. No. 176, 1912, p. 130. 216 FOOD INGESTION AND ENERGY TRANSFORMATIONS. in spite of all efforts, went to sleep in last period. Nitrogen in urine per hour 8h15m a. m. to 4h13m p. m., 0.38 gram; 4h13m p. m. to 5H5m p. m., 0.29 gram. J. J. C.. 9h01m a. m. to 4h20m p. m., December 6, 1910. 63.3 kilograms.— Low-carbohydrate diet on preceding day. Very quiet in basal periods, most of time asleep; asleep at end of both first and second food periods; during third period adhesive plaster became kosened while subject was asleep; he doubtless inhaled air; in seventh period, slept most of time but was constantly awakened by observer. To prevent possible leakage of air during sleep, rub- ber bandage used around head and over upper lip in eighth and ninth food periods, but even with this device mouth apparently opened once in latter period; as bandage caused discomfort, it was removed and only the adhesive plaster alone used thereafter. Awake in last period. Nitrogen in urine per hour 8h25ra a, m. to 4h40m p. m., 0.48 gram. J. J. C., 8h49m a. m. to 3h02™ p. m., December 8, 1910. 63.5 kilograms.- High-carbolrydrate diet on preceding day. Wooden head-rest used. Subject slept between first and second basal periods and continued to be very sleepy, requiring entire attention of one observer to keep him awake. In first food period not so sleepy as previously, but observer spoke to him frequently to make sure that he was awake; slight activity in second food period; several movements in fourth food period; asleep most of fifth and sixth periods, although frequently awakened. In seventh and eighth periods fell asleep; when awakened made slight movements; in last period drew deep breath. Nitrogen in urine per hour 7h30m a. m. to 3h14m p. m., 0.39 gram. J. J. C., 8h48m a. m. to 5h21m p. m., December 20, 1910. 64.7 kilograms.- Subject sat in chair. High-carbohydrate diet on preceding day. Some sleep between second and third basal periods; coughed once in third basal period with possibility of slight loss of air; left nosepiece loosened in fourth period; possible leak in left nosepiece in fourth food period ; a number of deep breaths in fifth food period; very quiet in eighth and ninth periods, but no tendency toward sleep. Nitrogen in urine per hour 7h10m a. m. to 5h23m p. m., 0.20 gram. V. G., 8*17m a. m. to 2h53m p. m., November 18, 1910. 53.9 kilograms.- Two pillows and wooden head-rest. Very quiet during first five basal periods, at times showing tendency to go to sleep; fell asleep once and slept between periods. Quiet in last two basal periods. Left room for urinating before taking sucrose. In last food period found it difficult to breathe; several very deep respirations. Nitrogen in urine per hour 7h50m a. m. to Ih15ra p. m., 0.49 gram; Ih15m p. m. to 3h20m p. m., 0.41 gram. V. C., 8h35m a. m. to 4h47m p. m., November 30, 1910. 53.9 kilograms.— High-carbohj'drate diet day preceding. Slept most of first basal period and also throughout second and third basal periods ; sound asleep in third food period and slept during fifth food period. Awake most of sixth food period, but slept again part of seventh food period. Apparatus tested in intermission of one and one-half hours between seventh and eighth food periods. Some nausea at this time. Defecated at 3h37m p. m. Nitrogen in urine per hour 7 a. m. to 3h37m p. m., 0.31 gram; 3''37in p. m. to 5h19m p. m., 0.24 gram. V. G., 8*21m a. m. to o*46m p. m,, November .?/, 1910. 53.9 kilograms.- First and second basal periods very quiet; very sleepy in third basal period and after several efforts to keep him awake was allowed to sleep. Slight movement in sixth period; asleep most of eighth period and very quiet. In food periods, very quiet, coughing once in fourth food period. Nitrogen in urine per hour 6h45m a. m. to 3h05m p. m., 0.18 gram; 3h05m p. m. to 5h50m p. m., 0.20 gram. INGESTION OF CARBOHYDRATES. 217 TABLE 149. — H. H. A., January 2, 1912. Lying. (Values per minute.) Sucrose: Amounts, 100 grams sucrose, juice of one lemon; energy, 408 cals.; from carbohydrates, 100 p. ct. Time. Ventila- tion (reduced). Average respiration rate. Carbon dioxide. Respira- tory quotient. Oxygen. Average pulse rate. Heat (com- puted). Without food: Av. of 3 periods . With food:1 9h22ma.m liters. 4.29 5.17 12 11 c.c. 153 209 0.72 87 c.c. 213 239 66 73 cals. 1.00 1 17 9 45 a.m . . . 6 73 15 242 1 05 230 79 1 18 10 14 a.m 6.86 15 238 .98 243 76 1.22 11 05 a.m 6.85 15 229 .93 245 80 1.22 1 1 34 a.m 5.76 14 201 .84 239 85 1.16 12 41 p.m 4.62 12 173 .76 228 80 1.08 1Subject drank sucrose and lemon juice in 400 c.c. of water at 9h12m a. m. TABLE 150. — L. E. E., May 15, 1911. Lying. (Values per minute.) Sucrose: Amounts, 100 grams sucrose, juice of half lemon; energy, 402 cals.; from carbohy- drates, 100 p. ct. Time. Average respiration rate. Carbon dioxide. Respiratory quotient. Oxygen. Average pulse rate. Heat (computed). Without food: Av. of 3 periods . . With food:1 10h17ma.m .... 9 14 c.c. 189 235 0.78 93 c.c. 243 254 60 58 cals. 1.16 1 26 10 47 a.m . . . 12 280 1 00 280 64 1 41 11 30 a.m 14 272 98 278 64 1 40 12 15 p.m 14 219 93 236 61 1 17 1 17 p.m 10 204 87 234 56 1.14 2 07 p.m 9 207 83 248 55 1.20 3 03 p.m 8 196 76 259 55 1.23 'Subject drank solution (325 c.c.) at 9h56m a. m. TABLE 151. — A. F. G., May 20, 1911. Lying. (Values per minute.) Sucrose: Amounts, 100 grams sucrose, juice of half lemon; energy, 402 cals.; from carbohy- drates, 100 p. ct. Time. Average respiration rate. Carbon dioxide. Respiratory quotient. Oxygen. Averag'e pulse rate. Heat (computed) . Without food: Av. of 3 periods . . With food:1 10h29ma.m 16 17 c.c. 178 227 0.86 .95 c.c. 207 238 61 65 cals. 1.01 1.19 11 19 a.m. . . 19 254 97 263 71 1.32 11 54 a.m. 15 223 70 1.17 12 33 p.m. . . 16 197 93 212 68 1.05 1 14 p.m 18 181 83 218 67 1.05 1 60 p.m 17 178 82 216 65 1.04 'Subject drank solution (325 c.c.) at 10h13m a. m. 218 FOOD INGESTION AND ENERGY TRANSFORMATIONS. TABLE 152. — C. H. H., May 10, 1911. Lying. (Values per minute.) Sucrose: Amounts, 100 grams sucrose, juice of half lemon; energy, 402 cals.; from carbohydrates, 100 p. ct. Time. Average respiration rate. Carbon dioxide. Respiratory quotient. Oxygen. Average pulse rate. Heat (computed). Without food: Av. of 3 periods . . With food:1 10h35ma.m 14 14 c.c. 171 238 0.86 .98 c.c. 200 244 56 59 cals. 0.98 1.23 11 01 a.m 13 214 .90 237 62 1.17 11 35 a.m . 14 217 .96 226 64 1.13 12 22 p.m 14 225 .99 228 64 1.15 12 59 p.m 13 186 .90 206 59 1.01 1 32 p.m 13 167 .87 193 57 .94 2 10 p.m 15 184 .84 218 59 1.06 Subject drank solution (325 c.c.) at 10hllm a. m. TABLE 153.— H. L. H., May 17, 1911. Lying. (Values per minute.) Sucrose: Amounts, 100 grams sucrose, juice of half lemon; energy, 402 cala.; from carbohydrates, 100 p. ct. Time. Average respiration rate. Carbon dioxide. Respiratory quotient. Oxygen. Average pulse rate. Heat (computed) . Without food: Av. of 3 periods . . With food:1 10h30ma.m 14 15 c.c. 191 264 0.82 .99 c.c. 232 268 64 65 cals. 1.12 1.35 11 18 a.m 14 244 .94 259 75 1.29 12 49 p.m 15 213 .96 222 67 1.11 1 27 p.m 16 193 .83 233 63 1.13 2 06 p.m 15 203 .78 259 67 1.24 'Subject drank solution (325 c.c.) at 9h57m a. m. TABLE 154. — Prof. C., November 20, 1909. Lying. (Values per minute.) Sucrose and black coffee: Amounts, 100 grams sucrose, 200 grams coffee; nitrogen, 0.16 gram; total energy, 424 cals. Fuel value: Total, 422 cals.; from carbohydrates, 99 p. ct.; from protein, 1 p. ct. Time. Average respiration rate. Carbon dioxide. Respiratory quotient. Oxygen. Average pulse rate. Heat (computed). Without food: Av. of 4 periods . . With food:1 10h36ma.m. . . . 14 15 c.c. 203 306 0.86 1 07 c.c. 236 286 63 71 cals. 1.15 1 44 10 57 a.m 14 297 1 06 279 67 1 41 11 20 a.m 15 271 98 277 68 1 39 'Subject drank sucrose and coffee at 10h31m a. m. INGESTION OF CARBOHYDRATES. 219 TABLE 155. — Prof. C., November 22, 1909. Lying. (Values per minute.) Sucrose and black coffee: Amounts, 100 grams sucrose, 200 grams coffee; nitrogen, 0.16 gram; total energy, 424 cals. Fuel value: Total, 422 cals.; from carbohydrates, 99 p. ct. ; from protein, 1 p. ct. Time. Average respiration rate. Carbon dioxide. Respiratory quotient. Oxygen. Average pulse rate. Heat (computed). Without food : Av. of 3 periods . . With food :« Ih25mp.m 14 14 c.c. 213 302 0.88 1 10 c.c. 241 275 65 55 cals. 1.18 1 39 1 41 p.m 15 275 98 281 57 1 41 2 04 p.m 14 249 91 273 57 1 35 2 27 p.m 16 242 90 268 58 1 32 JSubject drank sucrose and coffee at about 1 p. m. TABLE 156. — A. J. 0., December 29, 1914- Lying. (Values per minute.) Sucrose: Amount, 100 grams; energy, 396 cals.; from carbohydrates, 100 p. ct. Time. Ventila- tion (reduced) . Average respiration rate. Carbon dioxide. Respira- tory quotient. Oxygen. Average pulse rate. Heat (com- puted) . Without food: Av. of 3 periods . With food:1 10h34ma.m . . liters. 6.36 7 90 18.3 19 0 c.c. 224 299 0.88 1 03 c.c. 254 290 60 cals. 1.24 1 46 10 37 a.m 10 41 a.m 7.74 8.68 17.8 19 2 300 329 1.08 1 12 277 293 1.40 1 48 10 46 a.m 8 65 19 4 337 1 14 294 1 48 10 51 a.m 8 88 19 0 347 1 14 305 1 54 10 56 a.m 8 65 17 2 345 111 311 1 57 11 15 a.m... 8 02 17 3 313 1 00 314 67 1 58 11 49 a.m. . . 8 30 20 0 314 1 03 305 68 1 54 'Subject drank mixture (about 300 c.c.) of sucrose and cereal coffee at 10h27m a. m. About 1 gram of the preparation per 200 c.c. was used for the cereal coffee. TABLE 157. — J. J. C., November 22, 1910. Lying. (Values per minute.) Sucrose: Amounts, 75 grams sucrose, juice of half lemon; energy, 303 cals.; from carbohydrates, 100 p. ct. Time. Average respiration rate. Carbon dioxide. Respiratory quotient. Oxygen. Average pulse rate. Heat (computed) . Without food : Av. of 4 periods . . With food:1 4h20mp.m 16 17 c.c. 202 239 0.87 97 c.c. 231 247 63 60 cals. 1.13 1 24 4 45 p.m 17 270 1 03 262 61 1 32 5 13 p.m. 16 251 1 00 252 65 1 27 'Subject drank sucrose and lemon juice in 150 c.c. of water at 4b17m p. m. 220 FOOD INGESTION AND ENERGY TRANSFORMATIONS. TABLE 158. — J. J. C., December 6, 1910. Lying. (Values per minute.) Sucrose: Amounts, 75 grams sucrose, juice of one lemon; energy, 309 cals. ; from carbohydrates, 100 p. ct. Time. Average respiration rate. Carbon dioxide. Respiratory quotient. Oxygen. Average pulse rate. Heat (computed). Without food : Av. of 3 periods . . With food:1 10b51ma.m 16 17 c.c. 190 205 0.80 84 c.c. 238 243 64 63 cals. 1.14 1 18 11 20 a.m . . . 16 257 95 270 66 1 35 11 55 a.m . . 17 248 71 1 30 12 35 p.m . . 15 223 87 255 72 1 2*» 1 11 p.m 16 222 92 242 69 1 20 1 44 p.m 15 216 88 245 70 1 20 2 18 p.m 14 212 87 244 66 1 19 2 51 p.m 15 207 87 238 68 1 IB 3 28 p.m 17 208 70 1 18 4 05 p.m 20 206 84 244 68 1 18 Subject drank sucrose and lemon juice in 150 c.c. of water at 10h42m a. m. TABLE 159. — J. J. C., December 8, 1910. Lying. (Values per minute.) Sucrose: Amounts, 75 grams sucrose, juice of one lemon; energy, 309 cals.; from carbohydrates- 100 p. ct. Time. Average respiration rate. Carbon dioxide. Respiratory quotient. Oxygen. Average pulse rate. Heat (computed). Without food : Av. of 4 periods . . With food:1 Ilh04ma.m 17 18 c.c. 202 246 0.85 1 04 c.c. 237 237 70 66 cola. 1.15 1 20 11 37 a.m 17 264 1 01 261 68 1 32 12 11 p.m 16 254 1.00 253 70 1.28 12 41 p.m 15 228 71 1.16 1 08 p.m .... 18 235 1 01 232 74 1 17 1 41 p.m 18 213 .93 228 63 1.13 2 17 p.m 17 204 .90 227 65 1.12 2 47 p.m 18 210 89 236 63 1.16 Subject drank sucrose and lemon juice in 150 c.c. of water at lO^SS™ a. m. INGESTION OF CARBOHYDRATES. 221 TABLE 160. — J. J. C., December SO, 1910. Sitting. (Values per minute.) Sucrose: Amounts, 75 grams sucrose, juice of one lemon; energy, 309 cals.; from carbohydrates, 100 p. ct. Time. Average respiration rate. Carbon dioxide. Respiratory quotient. Oxygen. Average pulse rate. Heat (computed). Without food: Av. of 5 periods . . With food:1 ll^T^a.m 19 19 c.c. 196 226 0.85 .91 c.c. 231 249 67 65 cn.lt. 1.12 1.23 11 52 a.m 20 259 1.02 253 63 1.28 12 24 p.m 20 250 1.01 248 65 1.25 12 51 p.m 17 233 .95 245 65 1.22 1 25 p.m 20 223 .92 243 72 1.20 1 53 p.m 17 204 .89 229 69 1.12 2 19 p.m. 16 206 .92 224 61 1.11 4 45 p.m . 21 209 .89 234 66 1.15 5 06 p.m . 21 203 .88 231 65 1.13 1Subject drank sucrose and lemon juice in 150 c.c. of water at Hh16m a. m. TABLE 161. — V. G., November 18, 1910. Lying. (Values per minute.) Sucrose: Amounts, 75 grams sucrose, juice of one lemon; energy, 309 cals.; from carbohydrates, 100 p. ct. Time. Average respiration rate. Carbon dioxide. Respiratory quotient. Oxygen. Average pulse rate. Heat (computed) . Without food: Av. of 7 periods . With food:1 Ih30mp.m 20 22 c.c. 203 216 0.83 .83 c.c. 244 260 63 C'il.t, 1.18 1.26 2 03 p.m . ... 22 245 .91 270 70 1.33 2 38 p.m 18 225 .89 253 73 1.24 Subject drank sucrose and lemon juice in 150 c.c. of water at Ih19m p. m. TABLE 162. — V. G., November 30, 1910. Lying. (Values per minute.) Sucrose: Amounts, 75 grams sucrose, juice of one lemon; energy, 309 cals.; from carbohydrates, 100 p. ct. Time. Average respiration rate. Carbon dioxide. Respiratory quotient. Oxygen. Average pulse rate. Heat (computed). Without food : Av. of 4 periods . . With food:1 Ilh15ma.m 19 21 c.c. 190 227 O.M .94 c.c. 226 242 56 63 cals. 1.10 1.20 11 50 a.m 21 216 93 233 64 1.16 12 21 p.m 21 241 1 01 239 61 1.21 12 58 p.m 19 245 .97 252 63 1.26 1 31 p.m 20 213 94 227 65 1.13 2 03 p.m 17 238 .98 244 68 1.23 2 45 p.m 20 206 .91 227 65 1.12 4 32 p.m. 20 221 .93 237 57 1.18 Subject drank sucrose and lemon juice in 150 c.c. of water at Ilh07m a. m. 222 FOOD INGESTION AND ENERGY TRANSFORMATIONS. TABLE 163. — V. G., November 21, 1910. Lying. (Values per minute.) Sucrose: Amounts, 73 grams sucrose, juice of half lemon; energy, 295 cals. ; from carbohydrates, 100 p. ct. Time. Average respiration rate. Carbon dioxide. Respiratory quotient. Oxygen. Average pulse rate. Heat (computed). Without food: Av. of 9 periods. . With food :l 3h17mp.m 21 19 c.c. 200 207 0.84 84 c.c. 238 245 65 63 cals. 1.15 1 19 3 50 p.m 23 264 1 06 250 64 1.26 4 22 p.m 20 232 96 242 71 1.21 5 08 p.m 18 235 94 249 73 1.24 5 32 p.m 21 238 95 250 73 1 25 Subject drank sucrose and lemon juice in 150 c.c. of water at 3h10m p. m. LACTOSE EXPERIMENTS. K. H. A., 8h45m a. m. to Ih07m p. m., May 23, 1912. 65.8 kilograms.— At 10h30m p. m. on preceding day took corn breakfast food (dry) with milk and sugar, one cup coffee with milk and teaspoonful sugar, and one ham sandwich. Drowsy in second food period; complained of pain in stomach in fifth food period, but was better in sixth food period. L. E. E., 8h48m a. m. to 3hlom p. m., June 5, 1911. 59.6 kilograms. — Slept a moment or two in second basal period and a little in second food period, also in intermissions between first and second food periods and between second and third food periods; somewhat restless between fifth and sixth food periods. Nosepieces out of position and leaked near end of sixth food period. In seventh food period found breathing difficult, felt faint, and breathed very deeply, as absorber failed to absorb carbon dioxide readily. Nitrogen in urine per hour 8 a. m. to 10h30ra a. m., 0.53 gram; 10h30m a. m. to 2h25m p. m., 0.44 gram. C. H. H., 9h03m a. m. to 3h34in p. m., May 23, 1911. 54.9 kilograms.— Awake and very quiet, remaining practically in same position throughout experiment; in last food period more wide awake than in previous periods. Nitrogen in urine per hour 7h10m a. m. to 12h44m p. m., 0.38 gram; 12h44m p. m. to 3h50m p. m., 0.42 gram. H. L. H., 8h51m a. m. to 3h%4m p. m., June 7, 1911. 60.4 kilograms.— Moved feet in first period; very restless between first and second periods; flies troubled him in second basal period; very quiet in fifth and sixth food periods; flies again troubled him in seventh food period. Nitrogen in urine per hour 6h35m a. m. to Ilh36m a. m., 0.44 gram; Ilh36m a. m. to 2h35m p. m., 0.39 gram. A. J. 0., 8h58m a. m. to lhllm p. m., January 4, 1915. 70.1 kilograms. — Length of periods irregular, ranging from 3 to 12 minutes. Nitrogen in urine per hour, 7h50m a. m. to 10h20m a. m., 0.44 gram; 10h20m a. m. to Ih15m p. m., 0.57 gram. INGESTION OF CARBOHYDRATES. 223 TABLE 164.— K. H. A., May 23, 1912. Lying. (Values per minute.) Lactose: Amounts, 100 grams lactose, juice of one lemon; energy, 385 calg. ; from carbohydrates, 100 p. ct. Time. Ventila- tion (reduced). Average respiration rate. Carbon dioxide. Respira- tory quotient. Oxygen. Average pulse rate. Heat (com- puted). Without food: Av. of 3 periods . With food:1 10h07ma.m .... liters. 5.36 5.44 13.1 14.0 c.c. 196 199 0.81 .79 c.c. 243 253 51 47 cols. 1.17 1.21 10 42 a.m . 5.33 14.1 199 46 1.21 11 15 a.m 6 59 15 5 240 .95 253 50 1.26 11 47 a.m 6.90 17.6 236 .96 245 59 1.22 12 18 p.m 6.65 15.8 237 .95 250 59 1.25 12 52 p.m 6.45 15.2 236 .99 239 61 1.20 'Subject drank lactose and lemon juice in 325 c.c. of water at 9h54m a. m. TABLE 165. — L. E. E., June 5, 1911. Lying. (Values per minute.) Lactose: Amounts, 100 grams lactose, juice of two-thirds lemon; energy, 381 cals. ; from carbo- hydrates, 100 p. ct. Time. Average respiration rate. Carbon dioxide. Respiratory quotient. Oxygen. Average pulse rate. Heat (computed). Without food : Av. of 3 periods . . With food:1 10h44ma.m 11 14 a.m 13 16 16 c.c. 189 237 232 0.83 .95 .94 c.c. 229 256 248 58 54 55 cals. 1.11 1.27 1.23 11 48 a.m 16 228 92 248 57 1.23 12 43 p.m. 12 236 96 247 57 1.23 1 13 p.m 15 214 .92 233 59 1.15 1 56 p.m 13 193 57 1.10 3 00 p.m 11 235 55 1.14 'Subject drank solution (325 c.c.) at 10h06m a. m. TABLE 166.— C. H. H., May 23, 1911. Lying. (Values per minute.) Lactose: Amounts, 100 grams lactose, juice of half lemon; energy, 379 cals.; from carbohydrates, 100 p. ct. Time. Average respiration rate. Carbon dioxide. Respiratory quotient. Oxygen. Average pulse rate. Heat (computed). Without food: Av. of 2 periods . . With food:1 10h17ma.m 15 15 c.c. 167 184 0.83 .79 c.c. 202 233 59 58 cals. 0.98 1.12 10 46 a.m 15 184 .84 220 57 1.07 11 20 a.m 15 189 90 211 58 1.04 11 52 a.m 15 199 88 227 58 1.11 12 25 p.m 16 206 89 232 60 1.14 1 05 p.m 14 183 86 213 57 1.04 1 40 p m 15 178 84 212 56 1.03 2 14 p.m 15 163 .81 202 54 .97 3 17 p.m 15 172 73 235 56 1.11 'Subject drank solution (325 c.c.) at 10 a. m. 224 FOOD INGESTION AND ENERGY TRANSFORMATIONS. TABLE 167. — H. L. H., June 7, 1911. Lying. (Values per minute.) Lactose: Amounts, 100 grams lactose, juice of half lemon; energy, 379 cals. ; from carbohydrates. 100 p. ct. Time. Average respiration rate. Carbon dioxide. Respiratory quotient. Oxygen. Average pulse rate. Heat (computed). Without food: Av. of 2 periods . . With food:1 10hlSma.m 15 16 c.c. 191 207 0.82 .84 c.c. 232 247 59 61 cals. 1.12 1 20 11 06 a.m 16 236 96 247 64 1 23 11 53 a.m 15 228 93 246 63 1 22 12 45 p.m 16 222 90 247 57 1 22 1 16 p.m 16 201 88 228 59 1 12 2 02 p.m 16 194 81 239 56 1 15 3 09 p.m 15 196 .79 248 58 1.19 ^Subject drank solution (325 c.c.) at 9h53m a. m. TABLE 168. — A. J. O., January 4, 1915. Lying. (Values per minute.) Lactose: Amount, 100 grams; energy, 374 cals.; from carbohydrates, 100 p. ct. Time. Ventila- tion (reduced). Average respiration rate. Carbon dioxide. Respira- tory quotient. Oxygen. Average pulse rate. Heat (com- puted). Without food : Av. of 10 periods. With food :L Ilh43ma.m 11 46 a.m liters. 6.20 7.33 7.18 19.3 21.0 21.0 c.c. 211 246 236 0.84 .88 .88 c.c. 251 281 267 60 cals. 1.22 1.38 1.31 11 49 a.m 7 00 20 0 240 .90 267 1.31 11 53 a.m . . . 7 27 20 6 251 94 268 1.33 11 58 a.m 7 52 18 6 276 1 01 272 1.37 12 03 p.m 7.82 20.4 279 1.01 275 1.39 12 20 p.m 7 95 19.2 300 1.01 297 59 1.60 1 02 p.m 7 82 20 6 274 .95 288 61 1.44 Subject drank mixture (about 300 c.c.) of lactose and cereal coffee at Ilh39m a. m. About 1 gram of the preparation per 200 c.c. was used for the cereal coffee. GENERAL DISCUSSION OF RESPIRATION EXPERIMENTS WITH CARBOHYDRATES. An inspection of tables 126 to 168 shows that the typical picture of a marked increase in the carbon-dioxide production appears in practi- cally every case. The increment in the oxygen consumption, although not so large as that for the carbon-dioxide production, also appears in most of the experiments. Naturally the values for the heat produc- tion, computed from the gaseous exchange, show corresponding incre- ments. The increase in the carbon-dioxide production is paralleled by a marked rise in the respiratory quotient which, in a large number of periods, exceeds unity. This is in harmony with the results obtained in the calorimeter experiments, for although it was not feasible to dis- cuss the respiratory quotients for those experiments, since the basal INGESTION OF CARBOHYDRATES. 225 respiratory quotients for the same day were not obtained in many cases, we may note that most of the quotients after the ingestion of carbohydrate showed a value of 0.90 or above. Since the average respiratory quotient of normal man in the post-absorptive condition is not far from 0.83, it is obvious that these quotients above 0.90 sub- stantiate the general observation that the respiratory quotient after carbohydrate ingestion is usually decidedly increased. In the computation of the heat production from the oxygen con- sumption and the respiratory quotient, a difficulty is immediately encountered in the fact that the respiratory quotient is frequently over 1, especially the non-protein respiratory quotient. Experimental evi- dence as to the calorific value of oxygen and carbon dioxide under these conditions is much needed. An investigation of this problem is now in progress in this laboratory; pending its completion we have assumed, in common with other investigators, that when the quotient is above 1, the calorific values of carbon dioxide and oxygen are the same as those when the quotient is 1. The computations of the heat production were based entirely upon the oxygen consumption, since the carbon-dioxide excretion is greatly increased as a result of intermediary metabolism, with a possible splitting off of carbon dioxide accompanied by only minor increases in the production of heat. MAXIMUM EFFECT ON METABOLISM OF CARBOHYDRATE INGESTION (INDIRECT CALORIMETRY). We have reason to believe that not only the different sugars but also the different amounts of sugars vary somewhat in regard to the actual height to which the metabolism may be increased and the time when the maximum metabolism appears. It is important, therefore, to determine as accurately as possible both of these factors. In the calo- rimeter experiments it was found that the maximum heat production occurred some time during the first or second hour. Since in the res- piration experiments observations are made every 15 or 20 minutes, it is possible to determine with considerable accuracy when the maximum or "peak" effect of carbohydrate ingestion appears. This is shown for the carbon-dioxide excretion, oxygen consumption, and heat pro- duction for all of the respiration experiments in tables 169 to 172. DEXTROSE. Ten experiments were made with 100 grams of dextrose with 9 subjects and four experiments with 75 grams of dextrose with two subjects. The greatest percentage increments are shown in table 169. In the experiments with 100 grams of dextrose the carbon-dioxide maximum increments show very large values. Thus, in no experi- ment was the maximum increment in the carbon-dioxide production 226 FOOD INGESTION AND ENERGY TRANSFORMATIONS. less than 12 per cent, while in one case it rose as high as 35 per cent, the average being 25 per cent. The average time at which the max- imum values occurred was If to If hours after food. The oxygen consumption shows maxima with wide degrees of divergence, these ranging from 3 to 22 per cent, with an average for the 10 experiments of 12 per cent. The average time when this maximum appeared was between 1 and 1| hours after food. The heat production varied from 6 to 24 per cent above the basal value, the average being 14 per cent. Like the carbon-dioxide production, this maximum increment occurred on the average between If and If hours after food. We thus have a fairly consistent picture with 100 grams of dextrose of an average maximum increase of 25 per cent in the carbon-dioxide production, 12 per cent in the oxygen consumption, and 14 per cent in the heat production, with an average time after food for the appearance of the maximum of If to If hours. TABLE 169. — Maximum effect of ingestion of dextrose on carbon dioxide, oxygen, and heat in respiration experiments. Carbon dioxide Oxygen. Heat (computed). Period Greatest Greatest Greatest Subject and date. of obser- vation.1 incre- ment above basal Hours after food. incre- ment above basal Hours after food. incre- ment above basal Hours after food. value. value. value. 100 grams dextrose. hrs. min. p. ct. p. ct. p. ct. K. H. A. .May 14, 19122. 4 7 26 1 to 1| 8 1 toll 12 1 to H J. C. C...Dec. 31, 19123. 3 21 12 If to 2 8 Ito i 8 (4>i to | J. J. C. ..Mar. 7, 191 13. 3 57 32 1 toll 17 Ito J 20 1 to 11 L. E. E. .May 29, 191 13. 3 53 30 3 to 31 8 2 to 2J 12 2 to 2} C. H. H..May 1, 19113. 6 6 22 1 toll 20 Ho f 19 ito 1 H. L. H..May 24, 191 13. 3 41 26 1 to 1| 13 1 toll 15 1 to 11 P. F. J...May 15, 19122 3 55 20 1\ to2f 3 f to 1 6 2\ tol' 2 B. M. K. .Dec. 30, 1912.. 5 0 24 2| to 2| 12 21 to 2\ 14 2| to:?} A. J. O. . .Dec. 11, 1914s. 1 27 35 11 to \\ 22 11 to H 24 IJtolJ Dr. P. R.May 3, 19122. 4 29 21 f tol 9 6U to If 11 2 to?! Average 4 0 25 1 MO 1 1 12 1 to 1} 14 H to ij 75 grams dextrose. J. J. C. . .Dec. 22, 19103. 1 43 22 1 to U 15 1 toll 17 1 to 11 J. J. C. . .Dec. 28, 19102. 2 50 22 If to 2 8 1 f to 2 10 If to 2 V. G Dec. 23 19103 3 59 14 2f to 3 15 1 to 1| 15 1 to H V. G.. Dec. 29, 19102 2 49 19 11 to lj 8 f to 1 9 1 1 to 1 J Average 2 50 19 If to 2 12 1 1 to 1 § 13 11 toli 'Period from the time when subject finished eating to the end of the last observation, except in cases when the increment of heat ended earlier. See tables 126 to 139 for complete observations. 2Sugar taken with juice of one lemon on this day. 'Sugar taken with juice of one-half lemon on this day. 4Same value occurs 11 to 1 3 and 1J to 2 hours after food. *In cereal coffee (about 300 c.c. solution). 'Same value occurs 2 to 21 hours after food. INGESTION OF CARBOHYDRATES. 227 In the 75-gram experiments the average of the maximum increment values for the carbon-dioxide production was 19 per cent and for the oxygen consumption was 12 per cent. The average of the maximum values for the heat production was 13 per cent, this being but slightly less than that found with 100 grams. Basing our conclusions upon these four experiments, therefore, the reduction in the amount of carbohydrate ingested from 100 to 75 grams produces but a relatively slight decrease in the maximum effect. The time at which this occurred was not greatly different from that in the 10 experiments with 100 grams of dextrose, being from 1 \ to 1| hours. Thus, with dextrose, the results obtained with the respiration appa- ratus completely confirm the observations with the respiration calo- rimeter that the maximum effect with carbohydrates is obtained inside of the first 1 or 2 hours. The average length of the observations, i. e., from the taking of the food to the end of the last experimental period, was 4 hours with 100 grams and 2h50m with the 75-gram amounts. It is clear that in both series of experiments the observation was sufficiently long to include the possible maximum effect. LEVULOSE. With 100 grams of levulose 7 experiments were made with as many different subjects. (See table 170.) The carbon-dioxide production showed even greater maximum increments than in the case of the dex- trose, namely, from 25 per cent to 38 per cent, with an average of 32 per cent. The maximum increment in the oxygen consumption ranged from 8 per cent to 14 per cent, with an average of 11 per cent. The "peak" effect in the heat production ranged from 11 per cent above basal to 18 per cent, with an average of 15 per cent. The experiments continued for an average length of 4h10m, the greatest exception being that with A. J. O., which was but Ih29m. On the average the maximum effect was obtained between lj and 1^ hours after the taking of food. Two experiments with but 75 grams, both with J. J. C., showed maximum values strikingly uniform with those obtained on the average with the 100-gram amount. Since there was but one subject, however, the comparison has no great value, particularly as no 100-gram experiment was made with this subject. Although the second experiment with J. J. C. was only Ih15m in length, it is probable that the maximum effect occurred in this time. SUCROSE. Eight experiments with 100 grams sucrose and seven experiments with approximately 75 grams sucrose give a fairly good picture of the maximum effect due to the ingestion of sucrose. The data are shown in table 171. In the last three experiments with 100 grams the length of the observation was not so great as in the experiments previously considered, and in one or two instances the experiment was probably 228 FOOD INGESTION AND ENERGY TRANSFORMATIONS. terminated before the effect had ceased. As the time at which the maximum effect occurred agrees fairly well with that in the other experiments, these short experiments are included in table 171. With 100 grams of sucrose the carbon-dioxide increments were exceptionally large, ranging from 38 to 58 per cent, with an average of 47 per cent. With the oxygen consumption, the maximum increment ranged from 15 per cent to 27 per cent with an average of 20 per cent. The maxi- mum increase in heat production ranged from 19 to 31 per cent with an average of 24 per cent. The highest increment occurred on the average from 45 to 60 minutes after the ingestion of the sugar. TABLE 170. — Maximum effect of ingestion of levulose on carbon dioxide, oxygen, and heat in respiration experiments. Carbon dioxide. Oxygen. Heat (computed). Period Great- Great- Great- of est est est Subject and date. obser- incre- Hours incre- Hours incre- Hours vation ' ment after ment after ment after above food. above food. above food. basal basal basal value. value. value. 100 grams levulose. hrs. min. p. ct. p. ct. p. ct. K. H. A.. May 18, 19122 3 38 32 1 toU 14 Ho 5 18 1 to i J. P. C.. .Apr. 3, 191 13 5 24 33 2 to 21 14 2 to 21 18 2 to 21 L. E. E. .May 22, 191 13 3 51 38 litoli 8 litoli 14 11 toll C. H. H..Mav 16, 19113 5 35 25 3| to3f 13 2 to 21 15 2 to 21 H. L. H..June 1, 191 13 o 13 31 Ho ! 8 Ho 1 12 *to * P. F. J. ..May 22, 19122 3 58 28 f to 1 9 3 to 31 11 «1J toH A. J. O. . .Dec. 8, 19 146 1 29 38 Ho 1 14 Ho J 17 Ho f Average 4 10 32 U to H 11 1 1 to 1 J 15 1 to 11 75 grams levulose. J. J. C. . .Dec. 31, 1910.. 6 47 34 litoli 16 U toU 18 n to H J. J. (\ . .Jan. 4, 191 12. 1 15 30 2 to 1 12 i ton 15 1 to 11 Average 4 1 32 1 to 11 14 litoli 17 n toil lPeriod from the time when subject finished eating to the end of the last observation, except when the increment of heat ended earlier. See tables 140 to 14S for complete observations. 2Sugar taken with juice of one lemon on this day. 3Sugar taken with juice of one-half lemon on this day. 'Same value occurs 2{ to 2\ hours after food. 'In cereal coffee (about 300 c.c. solution). The experiments in which 75 grains of sugar were taken do not lend themselves so easily for comparison as the 100-gram experiments, since they were made with only two subjects. The maximum increase in carbon-dioxide production ranged from 21 per cent to 35 per cent with an average of 30 per cent, while that for oxygen consumption ranged from 5 to 13 per cent with an average of 11 per cent. The maximum increase in heat production ranged from 10 per cent to 18 per cent with an average of 15 per cent. Comparing these values with the averages INGESTION OF CARBOHYDRATES. 229 found after the ingestion of 100 grams, we find a marked decrease, amounting to one- third to one-half of the increment noted in the 100- gram experiments. With all three factors the time at which the maxi- mum effect occurred is similar to that noted with the larger amount, namely, from 45 to 60 minutes after the ingestion of the carbohydrate. TABLE 171. — .\faximum effect of ingestion of sucrose on carbon dioxide, oxygen, and heat in respiration experiments. Carbon dioxide. Oxygen. Heat (computed). Period Great- Great- Great- of est est est Subject and date. lu obser- incre- Hours incre- Hours incre- Hours ment after ment after ment after vation. above food. above food. above food. basal basal basal value. value. value. 100 grams sucrose. hrs. min. p. ct. p. ct. p. ct. H. H. A. .Jan. 2, 19122 3 44 58 1 tn 3 2 IO 4 15 2 to 21 22 31 to 1| L. E. E. .May 15, 191 14 2 34 48 f to 1 15 | to 1 22 f to 1 A. F. G. .May 20, 191 14 3 52 43 1 toll 27 1 to 1 J 31 1 to H C. H. H. .May 10, 191 14 3 3 39 5 tO f 22 Jto I 26 Jto f H. L. H..May 17, 19114 3 7 38 Jto i 16 5 tO f 21 Ito ! Prof. C. . . Nov. 20, 19096 1 4 51 0 to J 21 0 to 1 25 0 to i Prof. C. . . Nov. 22, 19095 1 42 42 Ho f 17 i to 1 19 f to 1 A. J. O. . .Dec. 29, 19 146 1 30 55 I 2 24 I to 1 27 I to 1 Average 2 35 47 i to f 20 I to 1 24 1 to 1 75 grams sucrose. 4 w * J. J. C.. .Nov. 22, 19104 1 11 34 Ito f 13 1 t,^ 3 2 tO f 17 J to 1 J. J. C.. .Dec. 6, 19102 5 39 35 1 tol 13 | to 1 18 -J- to 1 J. J. C . . . Dec. 8, 19102 2 3 31 1 to 1 10 I to 1 15 I to 1 J. J. C.. .Dec. 20, 19102 2 52 32 4 to f 10 \ to f 14 1 fn 3 a TO 4 V. G Nov. 18, 1910= 1 34 21 f to 1 11 J to 1 13 J to 1 V. G Nov. 30, 19 102 3 54 29 1| to 2 12 If to 2 15 11 to 2 V. G Nov. 21, 19104 2 36 32 f to 1 5 (?)f to 1 10 f to 1 \verage 2 50 30 f tol 11 f to 1 15 f to 1 'Period from the time when subject finished eating to the end of the last observation, except in cases when the increment of heat ended earlier. See tables 149 to 163 for complete observations. 2Sugar taken with juice of one lemon on this day. 3Same value occurs 2 to 2j hours after food. 473 grams sugar taken with juice of one-half lemon on this day. 6In 200 grams coffee. "In cereal coffee (about 300 c.c. solution). "Same value occurs 2j to 2| hours after food. LACTOSE. Five observations with different subjects were made after the inges- tion of lactose, the amount being 100 grams in all instances. The time of observation averaged 3h23m. (See table 172.) The carbon-dioxide increment ranged from 22 to 42 per cent with an average of 27 per cent, while the oxygen maxima ranged from 4 to 18 per cent with an average of 11 per cent. The greatest increase in heat production ranged from 230 FOOD INGESTION AND ENERGY TRANSFORMATIONS. 8 to 23 per cent with an average of 14 per cent. The maximum effect for both carbon-dioxide production and heat production occurred on the average between 1| a,nd 1^ hours after the food was taken. The maximum for oxygen consumption was reached on the average 30 to 45 minutes after food. TABLE 172. — Maximum effect of ingeslion of 100 grants of lactose on carbon dioxide, oxygen, and heat in respiration experiments. Carbon dioxide. Oxygen. Heat (computed). Period of Great- Great- Great- Subject and date. obsei- vation.1 est incre- ment Hours after est incre- ment Hours after est incre- ment Hours after above food. above food. above food. basal basal basal value. value. value. hrs. win. p. ct. p. ct. p. ct. K. H. A.. May 2.3, 19122. . . 3 12 22 U to H 4 (3U to } 8 Htoli L. E. E. .June 5, 19114. . . 4 5 25 f to 1 12 f to 1 14 1 to 1 C. H. H. .Mav 23, 191 15. . . 4 30 23 2J to 2f 15 ito } 16 2ito2J H. L. H..June 7, 1911s. .. 3 38 24 ijtoii 6 '•JJto 1 10 litoli A. J. O.. .Jan. 4, 19157. . . 1 32 42 f to 1 18 \ to 1 23 J to 1 Average 3 23 27 li to H 11 A tn a 2 lO 4 14 li to 1J 'Period from the time when subject finished eating to end of last observation, except in cases when the increment of heat ended earlier. See tables 164 to 168 for complete observations. 2Sugar taken with juice of one lemon on this day. 3Same value occurs lj to 1| hours after food. 4Sugar taken with juice of two-thirds lemon on this day. 53ugar taken with juice of one-half lemon on this day. "Same value occurs lj to 1? and 2f to 3 hours after food. "In cereal coffee (about 300 c.c. solution). COMPARISON OF MAXIMUM INCREMENTS OBTAINED WITH VARIOUS PURE CARBOHYDRATES. A comparison of the percentages of greatest increase shown by the four sugars is given in table 173. The average period of observation was practically the same for all of the carbohydrates, although some- what less in the experiments with sucrose and the 75-gram experiments with dextrose. In all cases the observation was sufficiently long to obtain the maximum effect. The maximum increments in carbon-dioxide production for 100 grams of dextrose, levulose, and lactose were not far apart, being 25, 32, and 27 per cent, respectively, with an average maximum effect of 28 per cent; with sucrose the maximum increment was 47 per cent. A similar concordant effect is noted for the maximum increment in oxygen consumption for dextrose, levulose, and lactose, the highest values obtained being 12, 11, and 11 per cent, respectively, while with sucrose it was 20 per cent. The maximum increment in heat produc- tion was practically the same for dextrose, levulose, and lactose, ?'. e., from 14 to 15 per cent. With sucrose it was materially greater, 24 per INGESTION OF CARBOHYDRATES. 231 cent. It is thus clear that the maximum effect was markedly different with sucrose from that for any one of the other sugars studied. So far as the time relations are concerned, it appears that not only was the increment very much greater with sucrose, but that the maximum effect also appeared earlier than it did with any of the other sugars. It is possible that the early occurrence of the maximum effect with sucrose may be due to the cleavage which probably occurs immediately after absorption. TABLE 173. — Average maximum effect of carbohydrate ingestion in respiration experiments. Carbon dioxide. Oxygen. Heat (computed). No. Period Kind of sugar. Amt. of experi- ments. of observa- vation.1 Average maxi- Hours after Average maxi- Hours after Average maxi- Hours after mum effect. food. mum effect. food. mum effect. food. grams. fir.t. min. p. ct. p. ct. p. ct. Dextrose . 100 75 10 4 4 0 2 50 25 19 H to If If to 2 12 12 1 to 1-i- U to H 14 13 H to 1J li to U Levulose . 100 75 7 2 4 10 4 1 32 32 H to 1| 1 to H 11 14 U to H H to I* 15 17 1 to li li to 1J Sucrose. . 100 75 8 7 2 35 2 50 47 30 Ho ! f to 1 20 11 f to 1 f to 1 24 15 f to 1 3 to 1 Lactose. . 100 5 3 23 27 U toH 11 ito f 14 li to H Period from the time when subject finished eating to the end of the last observation, except in cases when the increment of heat ended earlier. See tables 126 to 168 for complete observations. In all of the experiments either 75 or 100 grams of the sugar were used. With dextrose and levulose the amount of sugar made but little difference in the maximum effect, but there was considerable variation with sucrose. With the smaller amount of sucrose there was a decrease in the maximum effect, which amounted to one- third to one- half of the increment noted in the 100-gram experiments. A simple explanation of this phenomenon is not found. Although the 100-gram experiments with sucrose were on the average somewhat shorter than those with either dextrose or levulose, it is clear that this lowering of maximum increment can not be due to variations in the length of period, for the maximum, which alone is under consideration here, always occurs early in the experiment. It is furthermore clear that the sugar tolerance is by no means exceeded, as 100 grams is not a large amount. One contaminating feature is the fact that in nearly every case the experiments with the two amounts were not made with the same indi- viduals or with the same groups of individuals. All of the 75-gram experiments with the three sugars were made with either J. J. C. or V. G., and the only 100-gram experiment with these two subjects was that with J. J. C. on March 7, 1911, when dextrose was given. Still it is hardly probable that the fact that the same group of individuals was not used accounts wholly for this difference in effect. It is at least 232 FOOD INGESTION AND ENERGY TRANSFORMATIONS. possible that the disintegration of sucrose as a result of cleavage may have produced stimulating substances, such as intermediary acid products, in somewhat larger amounts than those occurring in the preparation of levulose for final combustion or storage in the body. The data do not permit of closer analysis in searching for a cause for this variation. It is evident, however, that following the ingestion of sucrose a consider- ably greater stimulus to the metabolism may be expected than that occurring with any of the other sugars, at least so far as the maximum effect is concerned. TOTAL INCREMENT IN METABOLISM AFTER CARBOHYDRATE INGESTION (INDIRECT CALORIMETRY). In the preceding section special emphasis has been laid upon the maximum increment in terms of percentage of the basal value — in other words, the absolute height to which the basal metabolism can be increased by the ingestion of different carbohydrates. As was pointed out in the consideration of the calorimeter experiments (see page 200) , the total increment expressed as a percentage value can have but little significance, as the increase may extend over a considerable period of time and the basal value for this time will be directly proportional to the period; consequently the increment represents a continually decreasing percentage of the basal value. For these respiration experi- ments, therefore, it is likewise inexpedient to consider the percentage of total increment as referred to the basal value. On the other hand, it is perfectly feasible to compute the total increment in the metabolism. A series of tables has therefore been prepared showing the computed increments for carbon-dioxide production, oxygen consumption, and heat production in the period of observation following the ingestion of carbohydrate. As already explained on page 151, the increment in heat production for practically all of the respiration experiments has been computed from measured areas representing heat values superimposed on a fast- ing base-line observed preceding the ingestion of food. The increases in heat production with carbohydrates were obtained in this manner. The increments for carbon-dioxide production and oxygen consump- tion have been found by a method somewhat different, but yielding practically the same result. As in the case of the plotted area for heat production, values were interpolated for the interval between the time when the subject finished eating and the beginning of the first measured period and for the intervals between the periods of measurement. For the interval preceding the first measured period it was assumed that the increment per minute was one-half that found in the period; for each interval between measured periods the average of the per-minute increments observed in the periods preceding and following the inter- val was used. Multiplication of the duration in minutes of the inter- INGESTION OF CARBOHYDRATES. 233 vals and measured periods by the respective increments per minute resulted in totals of either carbon dioxide produced or oxygen absorbed. The totals for periods and intervals, when added together, gave the amounts for the total period in which increment was observed. The computation of the increment began with the time when the subject had finished eating and continued to the end of the last period of the experiment, or through the period in which the increment apparently ceased. The experiment of December 31, 1912, in which the subject J. C. C. took 100 grams dextrose, may be used to illustrate this method of com- puting the increment (see table 127, page 206) . The basal value for car- bon dioxide determined on the same day was 187 c.c. per minute. The amount per minute measured in the first period beginning at Ilh13m a. m. was 196 c.c., or an increment of 9 c.c. per minute for the 14 min- utes and 39 seconds of the period ; the total increment observed in the period (14.65 X 9) is therefore 132 c.c. Between the time when the subject finished eating and the beginning of this period there was an interval of 8 minutes. Assuming for this interval an increment per minute of one-half that observed in the first period, the total increment for the preliminary interval (8 X 4.5) was 36 c.c. The increase in carbon dioxide for the second period beginning at Ilh45m a. m. was 16 c.c. per minute, the total for the period (14.92 X 16) being 239 c.c. Between the first and second periods there was an interval of 17 min- utes and 21 seconds; assuming a value equal to the average of the per minute increments in the first two periods, the total increase in carbon dioxide for this interval (17.35 X 12.5) was 217 c.c. The results for the remaining periods and intervals are obtained in the same manner and the total increase in carbon dioxide to the end of the sixth period following the ingestion of dextrose was, therefore, the sum of the com- puted and measured increments (36 + 132+217+239+316+315+396 +349+550+270+372+195) or 3,387 c.c. The equivalent of this amount is 6.7 grams of carbon dioxide. For the same period of obser- vation, i. e., through the period ending at 2h26m p. m., the increment of oxygen computed and measured was 3 grams and the increase in heat obtained from the measured area of increment superimposed on the fasting base-line was 12 calories. The total increments for each sugar studied are shown in tables 174 to 177. Although the maximum effect, as we have seen, was obtained usually inside of the first 1| hours after the ingestion of the sugar, there was a positive increment in carbon-dioxide production, oxygen con- sumption, and heat production, which was measurable for a fairly long period. Usually the increments in oxygen consumption and heat production persisted for about the same length of time, and thereafter basal values were obtained for both these factors. Frequently the increment in the carbon-dioxide production continued for some time 234 FOOD INGESTION AND ENERGY TRANSFORMATIONS. longer; the total excess carbon dioxide is therefore given in a footnote, together with the period of time in which it was obtained. DEXTROSE. The total increments in the metabolism as a result of the ingestion of dextrose are given in table 174. Considering first only the increments obtained with 100 grams of dextrose, we find that the total increment in carbon-dioxide production ranged from 6.7 to 20.4 grams with an average increment of 12.5 grams. The increase in oxygen consump- TABLE 174. — Total increment of carbon dioxide, oxygen, and heat following ingestion of dextrose in respiration experiments. ] ncrement of— Period Subject and date. of observation.1 Carbon dioxide. Oxygen. Heat (computed) . 100 grams dextrose. hrs. min. grams. grams. cats. K. H. A. .May 14, 1912... 4 7 14.5 1.7 12 J. C. C. . .Dec. 31, 1912... 3 21 26.7 3.0 12 J. J. C....Mar. 7, 1911... 3 57 20.4 8.2 35 L. E. E...May 29, 1911... 3 53 317.1 3.4 18 C. H. H. .May 1, 1911... 6 6 12.1 6.5 24 H. L. H. .May 24, 1911... 3 41 413.2 3.4 17 P. F. J. . .May 15, 1912... 3 55 9.4 0.6 6 B. M. K..Dec. 30, 1912... 5 0 11.7 5.7 21 A. J. O. ..Dec. 11, 1914... 1 27 7.2 3.7 14 Dr. P. R..May 3, 1912... 4 29 12.7 4.1 19 Average . 4 0 12.5 4.0 18 75 grams dextrose. J. J. C... .Dec. 22, 1910... 1 43 5.8 3.8 13 J. J. C... .Dec. 28, 1910... 2 50 68.5 1.6 8 V. G Dec. 23, 1910... 3 59 8.2 5.1 19 V. G Dec. 29, 1910... 2 49 8.6 3.6 15 Average 2 50 7.8 3.5 14 'Period from the time when subject finished eating to the end of the last observation, except in cases when the increment of heat ended earlier. See tables 126 to 139 for complete observations. 27.1 grams for 4h14m. 320.8 grams for 5h23m. 418 grams for 4h59m. 611.7 grama for 5h4m. tion ranged from 0.6 to 8.2 grams with an average of 4 grams, while the increment in heat production ranged from 6 to 35 calories with an average of 18 calories. The average length of the period of observa- tion was 4 hours. In a few instances, namely, the experiments with J. C. C., L. E. E., and H. L. H., additional increments of 1 to 5 grams were obtained by further extension of the measurements. With the ingestion of 75 grams of dextrose the carbon-dioxide increment was reasonably constant, varying only from 5.8 to 8.6 grams with an aver- age of 7.8 grams. The increment in the oxygen consumption ranged from 1.6 to 5.1 grams with an average of 3.5 grams, while the incre- INGESTION OF CARBOHYDRATES. 235 ment in the heat production ranged from 8 to 19 calories with an average of 14 calories. The total increments found with the different amounts of dextrose are noticeably unlike. LEVULOSE. The results obtained in the experiments with levulose are given similar treatment in table 175. The increments for carbon-dioxide production ranged from 9.9 to 23.3 grams with 100 grams of levulose, with an average value of 18.2 grams. Those for oxygen consumption varied from 3 to 8.3 grams, with an average of 5.1 grams, while the total increments for heat production ranged from 12 to 36 calories, averaging 24 calories. The two experiments with 75 grams of levu- lose are so widely divergent in their results that the data are of doubtful TABLE 175. — Total increment of carbon dioxide, oxygen, and heat following ingestion of levulose in respiration experiments. ] increment of— Period Subject and date. of observation.1 Carbon dioxide. Oxygen. Heat (computed). 100 grams levulose. hrs. min. grams. grams. cals. K. H. A. .May 18, 1912... 3 38 15.2 4.0 20 J. P. C. ..Apr. 3, 1911... 5 24 23.3 8.3 36 L. E. E...May 22, 1911... 3 51 23.2 3.1 21 C. H. H. .May 16, 1911... 5 35 17.5 8.3 34 H. L. H. .June 1, 1911... 5 13 21.8 4.5 24 P. F. J. . .May 22, 1912... 3 58 16.7 4.2 20 A. J. O...Dec. 8,1914... 1 29 9.9 3.0 12 Average 4 10 18 2 5 1 24 75 grams levulose. J. J. C... .Dec. 31, 1910... 6 47 25.3 9.7 38 J. J. C....Jan. 4, 1911... 1 15 8.1 2.3 10 Average 4 1 16 7 6.0 24 from the time when subject finished eating to the end of the last observation, except in cases when the increment of heat ended earlier. See tables 140 to 148 for complete observations. value, but as both show a positive increment for all three factors, they are included in this comparison. The average values for the two experi- ments are not far from the averages for the larger amount of levulose. SUCROSE. The experiments with 100 grams of sucrose, which are compared in table 176, show total increments in the carbon-dioxide production ranging from 9.8 to 26 grams and averaging 16.1 grams. In the experi- ment with L. E. E., May 15, 1911, approximately 6 grams additional excess carbon dioxide were obtained in the later periods of the experi- 236 FOOD INGESTION AND ENERGY TRANSFORMATIONS. ments. The total increment in oxygen consumption ranged from 3.9 to 7.8 grams, with an average of 5.9 grams, while the total increase in the heat production varied from 15 to 36 calories, averaging 25 calories. In the experiments with 75 grams of sucrose, with but two subjects, the total increment in the carbon-dioxide production varied widely from 4.7 to 20.4 grams, averaging 11.9 grams. The total increment in the oxygen consumption ranged from 1.9 to 5 grams with an average of 3 grams, while the increment in the heat production ranged from 9 to 27 calories, with an average of 15 calories. From these figures it is seen that the smaller amounts of sugar produced a smaller total increment in all three factors, thus corresponding more or less to the decrease in the maximum effects noted for the results obtained with the 100 grams and 75 grams. TABLE 176. — Total increment of carbon dioxide, oxygen, and heat folloiuing ingestion of sucrose in respiration experiments. Increment of — Period Subject and date. of observation.1 Carbon dioxide. Oxygen. Heat (computed). 100 grams sucrose. hrs. min. grams. grams. cob. H. H. A. .Jan. 2, 1912... 3 44 26.0 7.7 36 L. E. E...May 15, 1911... 2 34 218.4 4.7 24 A. F. G...May 20, 1911... 3 52 15.1 7.8 30 C. H. H. .May 10, 1911... 3 3 15.7 7.0 28 H. L. H. .May 17, 1911... 3 7 16.4 5.2 23 Prof. C.. .Nov. 20, 1909... 1 4 10.7 3.9 15 Prof. C...NOV. 22, 1909... 1 42 9.8 4.3 16 A. J. O...Dec. 29, 1914... 1 30 16.4 6.3 26 Average . ... 2 35 16.1 5.9 25 75 grams sucrose. J. J. C... .Nov. 22, 1910... 1 11 7.2 2.3 10 J. J. C... .Dec. 6, 1910... 5 39 20.4 5.0 27 J. J. C....Dec. 8, 1910... 2 3 •11.1 1.9 11 J. J. C....Dec. 20, 1910... 2 52 412.3 3.4 16 V. G Nov. 18, 1910... 1 34 B4.7 2.3 9 V. G Nov. 30, 1910 . . 3 54 16.9 4.0 21 V. G.«....Nov. 21, 1910... 2 36 10.7 1.9 12 Average 2 60 11.9 3.0 15 'Period from the time when subject finished eating to the end of the last observation, except in cases when the increment of heat ended earlier. See tables 149 to 163 for complete observations. *23.9 grams for 5h23m 314.4 grams for 4h9m. <16.5 grams for 6h5cl. B22 grams for 5h40m. *73 grams sugar taken with juice of one-half lemon on this day. LACTOSE. The five experiments with lactose, grouped in table 177, show reasonable uniformity in the excess carbon dioxide produced, this ranging from 10.2 to 16 grams, with an average of 12.1 grams. In one INGESTION OF CARBOHYDRATES. 237 experiment with H. L. H., on June 7, 1911, which included a later 2- hour period, approximately 1 gram additional was excreted. The excess consumption of oxygen ranged from 1.8 to 6.4 grams, with an average of 4.3 grams, while the excess heat production varied from 10 to 22 calories, with an average of 18 calories. No experiments were made with less than 100 grams of lactose. TABLE 177. — Total increment of carbon dioxide, oxygen, and heat following ingestion of 100 grams lactose in respiration experiments. ] 'ncrement of— Subject and date. Period of observation.1 Carbon dioxide. Oxygen. Heat (computed). hrs. min. grams. grams. cals. K. H. A. .May 23, 1912... 3 12 10.2 1.8 10 L. E. E...June 5, 1911... 4 5 16.0 5.2 22 C. H. H. .Mav 23, 1911... 4 30 10.3 6.4 00 H. L. H. .June 7, 1911... 3 38 212.2 3.8 18 A. J. O. . .Jan. 4, 1915... 1 32 11.9 4.5 19 Average 3 23 12 1 4 3 18 'Period from the time when subject finished eating to the end of the last observation, except in cases when the increment of heat ended earlier. See tables 164 to 168 for complete observations. '13.2 grams for 5h31m. COMPARISON OF TOTAL INCREMENTS IN METABOLISM OBTAINED WITH VARIOUS PURE CARBOHYDRATES. A comparison of the several carbohydrates in their effect upon the metabolism can best be made by a tabular presentation of the averages for the total increments obtained with the different carbohydrates in this series of experiments. Such a grouping has been made in table 178. Comparing particularly the increments for the 100-gram amounts, we see that the differences in the average total increments in the carbon- dioxide production are not so very large. The effect is most pro- nounced with levulose and least with lactose, that for sucrose lying between the levulose and dextrose increments. According to the standards used in the earlier studies of carbohydrates, in which special emphasis was laid upon the carbon-dioxide excretion, it would be con- sidered that the effect with levulose was much more pronounced than that with sucrose and that the sugars affected the metabolism in these experiments in the decreasing order of levulose, sucrose, dextrose, and lactose. At first sight it is difficult to explain why the carbon dioxide produced should vary for the several sugars, and it is clear that the most careful analysis of the effect of sugar ingestion on the metabolism should not be based upon carbon-dioxide production. An examina- tion of the increments in oxygen consumption shows that in this case the maximum increment was obtained with sucrose, the order of effect 238 FOOD INGESTION AND ENERGY TRANSFORMATIONS. being sucrose, levulose, lactose, and dextrose, the lactose being but slightly greater than the dextrose. With the heat production the lowest total increment was found with both dextrose and lactose; the increases with sucrose and levulose were considerably larger, that for the sucrose being one calorie greater than the levulose increment. In the experiments with the 75-gram amounts, the general picture for the carbon-dioxide production is essentially the same as for the larger amount, the order being levulose, sucrose, and dextrose. For oxygen consumption and heat production the greatest increments were also obtained with levulose, but there were only two experiments with 75 grams of levulose, so that the averages are not perfectly comparable. TABLE 178. — Comparison of average increments of carbon dioxide, oxygen, and heat after 100 grams and 75 grams of carbohydrate in respiration experiments. Kind of sugar. No. of experi- ments. Carbon dioxide. Oxygen. Heat (com- puted). 100 grams: Dextrose . . . 10 grams. 12 5 grams. 4 0 rals. 18 Levulose 7 18 2 5 1 24 Sucrose 8 16 1 5 9 25 Lactose 5 12 1 4 3 18 Average of all sugars . . . 14.7 4.8 21 75 grams : Dextrose . 4 7 8 3.5 14 Levulose 2 16 7 6 0 24 Sucrose 7 11 9 3 0 15 Average of all sugars . . . 12.1 4.2 18 From the general picture obtained from all of the experiments, one is justified in saying that if the carbon-dioxide production is used as a basis of comparison, the increment of the ingestion of sugars upon the metabolism decreased in the order of levulose, sucrose, dextrose, and lactose. If the effect is measured by oxygen consumption and heat production, this statement should be revised, for in general the levulose and the sucrose had essentially the same effect, but dextrose had a much less influence than the other sugars. An average of the increments for the individual sugars shows for the 100 grams a general increase for carbon-dioxide production of 14.7 grams, for oxygen consumption of 4.8 grams, and for heat production of 21 calories; the averages for the 75-gram amounts are somewhat smaller. The statement made that the increment in the metabolism with sugars decreases in the order of levulose, sucrose, dextrose, and lactose, though based on the erroneous assumption that the carbon-dioxide incre- INGESTION OF CARBOHYDRATES. 239 ment with sugars would be proportional to the increment in the total metabolism, has been confirmed in other laboratories, although Lusk properly states that the differences are not very great. The data deter- mined by Lusk1 by indirect calorimetry after the ingestion of 50 grams of carbohydrates show that the increase over the basal metabolism during the second, third, and fourth hours was 30 per cent with glucose, 37 per cent with fructose, 34 per cent wi th sucrose, and but 3 per cent with lactose. By direct calorimetry he found a 15 per cent increase with glucose, 24 per cent with fructose, 28 per cent with sucrose, and 4 per cent with lactose. This latter series of values compares more nearly with those observed in our respiration experiments. Perhaps one of the most striking points in a consideration of the data in table 178 for these four sugars is the fact that the carbon-dioxide production, even with pure carbohydrates, is not a suitable measure of the energy transformations. The clear superiority of levulose and sucrose over dextrose in influ- encing metabolism is difficult to explain. One may assume that levu- lose has a special action upon cellular metabolism and that it is the levulose moiety of the sucrose molecule that produces the effect with sucrose, and yet one would expect the effect to be quantitatively con- siderably less with sucrose than with levulose if this be true. Unfor- tunately the experiments with the smaller amount of levulose, namely, 75 grams, are unsatisfactory and few in number, one of the two being obviously erratic with a larger heat production than in any of the levulose experiments. We are hardly justified, therefore, in drawing definite conclusions regarding the amount of levulose which will pro- duce a maximum stimulating effect. It is conceivable, however, that the effect of the sucrose due to the levulose portion may represent the maximum stimulating effect of levulose. On the other hand, we have also to consider the energy due to the hydrolysis of the sucrose molecule, which is assumed to be not far from 3.1 per cent. If in the experiments with sucrose we consider that 100 grams of sucrose have an energy content of 400 calories, we should expect somewhat over 12 calories to be produced as the result of hydrolysis. Deducting the 12 calories from the average total increment of 25 calo- ries obtained in our sucrose experiments, we find that there are 13 calories left which can be attributed to the influence of the separate components, levulose and dextrose, upon the metabolism. Assuming that the 100 grams of sucrose result in the formation of 50 grams each of levulose and dextrose, and using the average increments for 100 grams of these substances of 24 and 18 calories, respectively, which were found in our experiments, we would expect to obtain an effect of 12 plus 9 calories, or 21 calories, if the effect is a summation effect. It is clear, therefore, that the explanation of the 25 calories due to the ingestion of , Journ. Biol. Chem., 1915, 20, p. 590. 240 FOOD INGESTION AND ENERGY TRANSFORMATIONS. 100 grams of sucrose does not rest upon the summation effect of the resultant dextrose and levulose and the heat production due to hydrol- ysis, but that there must obviously be a compensation. Furthermore, the cells may refuse to react to the indirect stimulus of the result of hydrolysis and the direct stimulus of the two sugars on the basis of a summation effect. With practically all of the sugars except levulose, a somewhat decreased effect was found with the smaller amount of sugar. With levulose, therefore, we have a specific property entirely different from that found with the other sugars and in all probability we have here an intermediary metabolism which may perhaps best be consid- ered in connection with the study of the respiratory quotient. THE RESPIRATORY QUOTIENT AFTER INGESTION OF CARBOHYDRATES. Although the basal values for the respiratory quotients for the calo- rimeter experiments were not secured in all cases on the same day, quotients considerably above 0.90 were frequently obtained in the food experiments, which led to the reasonable assumption that there was a pronounced rise in this relationship, since the respiratory quotient for normal individuals in the post-absorptive condition is not far from 0.81 to 0.83. In the respiration experiments a careful study of the respira- tory quotients for short periods could be made; these have been recorded in tables 179 to 182 and show the time relations as well as the height of the quotients. In these tables we are considering only the quotients obtained in experiments with 100 grams of carbohydrate. DEXTROSE. The respiratory quotients for 10 experiments with dextrose are given in table 179. As will be seen from the protocols of these experiments, the post-absorptive value for the respiratory quotient was in practically every case an average of two or three reasonably agreeing periods. These values ranged from the low quotient of 0.70 to 0.87 with an average of 0.80. If we study the course of the respiratory quotient in the experiments, we find that shortly after the carbohydrate was given there was in practically every case a pronounced tendency for the quotient to reach a maximum about the second or third hour, and to fall off thereafter. It should be remembered, in studying these quotients, that each value depends upon the determinations of a single period and hence the general picture alone should be considered. The rise followed by a fall is so clear, however, as to leave no doubt as to the general course of the quotient after the ingestion of dextrose. An examination of the average values shows that within 20 minutes of the beginning of the experiment there was a slight fall from the average basal quotient of 0.80, which was followed by a steady increase until the maximum of 0.92 was reached in 2 to 2| hours; subsequently there was a tendency for the quotient to decrease. INGESTION OF CARBOHYDRATES. 241 On examination of the individual experiments, we find that in the two observations with the lowest basal value the maximum height of the respiratory quotient after food was also the lowest. Thus, in the experi- ment with J. C. C. on December 31, 1912, in which the initial quotient was 0.74, the highest quotient obtained was but 0.81, while in the experiment with B. M. K. on December 30, 1912, with a basal quotient of 0.70, the maximum quotient was 0.79. In these two instances a low glycogen store in the body at the beginning of the experiment can be inferred. This inference is further substantiated by the fact that a few days prior to this test these two subjects were living on a carbohydrate- free diet taken during a series of acidosis experiments. TABLE 179. — Influence ofingestion of 100 grams dextrose on the respiratory quotient in respiration experiments. Subject and date. Basal value. Time after ingestion of dextrose. Maxi- mum rise. o lHt« o £ £J3 o K. H. A.. May 14, 1912 J. C. C...Dec. 31, 1912 J. J. C. . .Mar. 7, 1911 L. E. E. .May 29, 1911 C. H. H. .May 1, 1911 H. L. H..Ma,y 24, 1911 P. F. J...Mav 15, 1912 B. M. K..Dec. 30, 1912 A. J. O. . .Dec. 11, 1914 Dr. P. R . May 3, 1912 Average 0.84 .74 .79 .78 .87 .82 .84 .70 .87 .78 0.72 0.85 .79 .82 0~77 .85 .89 .73 .94 .91 0.98 .78 .89 .88 .91 .91 .91 .96 1.01 .78 .90 .92 .93 .94 1.00 .92 .91 .94 .98 .97 .77 0.81 .94 .82 .94 .99 1.00 .81 0.89 .72 ... . . . 0.17 .07 .15 .16 .07 .16 .15 .09 .09 .13 '.94 .90 .94 3.93 .79 .80 2.84 4!74 0.93 0.87 .78 .67 5.8S .76 6.91 .83 .86 .87 .87 .89 .90 0.80 0.76 0.83 0.85 0.90 0.91 0.92 0.90 0.90 0.82 0.93 0.87 0.12 Average of two quotients, 0.96 and 0.91. 3Average of two quotients, 0.99 and 0.87. 2Average of two quotients, 0.88 and 0.80. 4Average of two quotients, 0.76 and 0.72. ""Average of four quotients, 0.91, 0.85, 0.87, and 0.87 (3 to 5 minute periods). 'Average of two quotients, 0.90 and 0.91 (5 minute periods). The comparison of the maximum increases in the respiratory quo- tients for the individual experiments, which is given in the last column, shows the lowest maximum rise to be 7 points above the basal, the highest 17 points, and the average maximum rise 12 points. While the lowest maximum rise was obtained in the experiment with the glycogen- poor subject J. C. C., it should be further noted that in an experiment with C. H. H. on May 1, 1911, in which the initial quotient was 0.87, there was the same rise of but 7 points; the relationship between the initial value and the maximum rise in the quotient is therefore by no means definitely established. In general, however, if the initial value is low, the maximum rise in the quotient is also low. 242 FOOD INGESTION AND ENERGY TRANSFORMATIONS. With dextrose the quotient for only one period was over unity. As it has been shown that the non-protein respiratory quotients are gener- ally two or three points higher than the measured quotients, all values of 0.98 or over would, strictly speaking, represent a non-protein respi- ratory quotient of unity. Even on this basis but relatively few peri- ods, i. e., 6 periods, show a non-protein respiratory quotient above 1. Respiratory quotients above 1 are commonly considered to indicate the formation of fat from carbohydrate. Furthermore, it is often inferred that the formation of fat from carbohydrate can occur only when the respiratory quotient is above 1, but this we do not believe to be true. LEVULOSE. The respiratory quotients in 7 experiments with levulose are given in table 180. The post-absorptive basal quotients range from 0.77 to 0.91, with an average of 0.85, somewhat higher than for the dextrose basal quotients, which averaged only 0.80. The general course of any one of the experiments is characteristic of the whole series in that there is an almost immediate rise after the ingestion of the carbohydrate and a tendency after several hours to return to approximately the basal value. The height of the respiratory quotient is much greater on the whole than was obtained with dextrose, as in all but one experiment it reached 1 or over. The lowest basal quotient, 0.77, was accompanied by one of the lowest maxima after food, while the highest basal quo- tient of 0.91 was followed by the highest observed maximum, 1.11. TABLE 180. — Influence of ingestion of 100 grams levulose on the respiratory quotient in respiration experiments. Time after ingestion of levulose. Subject and date. Basal value. Maxi- mum rise. o IN . o o-S 0 CO . HOI c j iN 0 06 -u i- HlCI o j CO S J *Jt sj oj O 3 o a iM o CO . 0.2 •** 3 0 S •* Hn ,— I 73 O tH +> A f— i N O to ^ H|M i-H -in IM X 3£ IM CO 3 g A «H[P« iM •& o| to o 0 £ ~£ •* to 5| 10 H. H. A... Jan. 2,1912 Prof. C....NOV. 20, 1909 Prof. C Nov. 22, 1909 L. E. E....May 15, 1911 A. F. G....May 20, 1911 C. H. H...May 10, 1911 H. L. H. ..May 17, 1911 A. J. O Dec. 29, 1914 Average 0.72 .86 .88 .78 .86 .86 .82 .88 0.87 1.07 1.05 1.06 1.10 .93 .95 .98 0.98 .98 1.00 .90 .99 1.00 0.98 0.93 0.84 0.76 0.33 .21 .22 .22 .11 .13 .17 .25 .91 .97 .94 1.03 0.90 .98 .96 .93 .99 .93 .90 .96 .87 !.83 .87 .83 0.83 0.76 .84 .78 21.08 31.13 0.83 1.01 1.03 0.98 0.97 0.95 0.95 0.91 0.83 0.82 0.76 0.21 'Average of two quotients, 0.83 and 0.82. 2Average of three quotients, 1.03, 1.08, and 1.12 (3 to 5 minute periods). 'Average of three quotients, 1.14, 1.14, and 1.11 (5 minute periods). special interest in this connection as possibly indicating a greater storage of glycogen or a more tenacious hold of the previous store than is ordinarily the case.1 The smallest rise in the quotient was obtained in the experiment with A. F. G. on May 20, 1911, this being but 11 points above the basal. The averages for all of the experiments show, with an average basal quotient of 0.83. a maximum value after the ingestion of sucrose of 1.03. The average maximum rise was 21 points. It should be observed that the average is obtained in this and similar tables by averaging the maximum increases for the individual experiments. LACTOSE. The respiratory quotients in five experiments with 100 grams of lac- tose are given in table 182. The basal values were remarkably uniform, ranging from 0.81 to 0.84, with an average of 0.83. None of the men had served as subjects for the carbohydrate-free experiments. With- out laying stress upon the individual experiments and considering only the general picture, we find that there was a slow, steady rise in the quotient which was followed by a fall ; the rise in this series was longer continued than in any of those previously discussed. Values of 0.98 or over are rare in the experiments with lactose, there being but three in all. The maximum rise of 18 points was found in the experiment with K. H. A., May 23, 1912; the minimum rise of 7 points occurred with C. H. H., on May 23, 1911; the average maximum rise for the whole series was 14 points. 'Benedict and Joslin, Carnegie Inst. Wash. Pub. No. 176, 1912, p. 131. INGESTION OF CARBOHYDRATES. 245 TABLE. 182. — Influence of ingestion of 100 grams laclose on the respiratory quotient in respiration experiments. Time after ingestion of lactose. Maxi- Subject and date. Basal value. 0 fcl 03 O - CO O 03 +-< u P a p a 0 p 8 mum rise. •* a |1 0* +> 43 43 += 43 *^ 43 "^ 43 o "-1 i— ( M N CO •* US K H A May 93 1912 0 81 0 79 0 95 0 96 0 95 0 99 0 18 LEE June 5 1911 83 0.93 .94 0.92 .96 .92 .13 C. H. H. .May 23, 1911 .83 .79 .84 .90 .88 .89 0.81 0.73 .07 \ J O Jan 4 1915 84 20 90 31 01 1 01 95 .17 H. L. H. .June 7, 1911 .82 .84 .96 .93 .90 .88 .81 .79 .14 Average 0.83 0.90 0.86 0.93 0.94 0.90 0.95 0.93 0.91 0.81 0.76 0.14 'Average of two quotients, 0.86 and 0.84. 2Average of four quotients, 0.88, 0.88, 0.90, and 0.94 (3 to 5-minute periods). 'Average of two quotients, 1.01 and 1.01 (5-minute periods). COMPARISON OP RESPIRATORY QUOTIENTS OBTAINED WITH VARIOUS PURE CARBOHYDRATES. A comparison of the respiratory quotients obtained after the inges- tion of various sugars is made in table 183, in which the number of experiments, the average post-absorptive values, the average quotients with their time relations, and the total rise are given for each of the sugars studied, only the results obtained with 100 grams being included in tliis summary. Except in the case of dextrose, the preliminary post- absorptive values were practically the same. That for dextrose, 0.80, was the lowest; the highest average basal quotient, 0.85, was obtained with levulose. The quotients after the ingestion of a carbohydrate show a rise in the first 20 minutes, with dextrose the only exception; the average quotient for dextrose fell from 0.80 to 0.76 during this period. Reference to table 179, from which this figure is drawn, shows that in three of the four experiments included in the average there was a positive decrease in the first period and that in the fourth experiment there was a rise of but one point. The explanation of the exceptional values found with dextrose is not simple. While we are much averse to using the commonplace sentence frequently em- ployed by observers to explain anomalies, ?'. 2, 51 grams; Oz, 46 grams; heat, 164 cals. Time elapsed since subject finished eating.1 Nitrogen in urine per 2 hours. Carbon dioxide. Oxygen. Heat. Total. Increase. Total. Increase. Total. Increase. 1 to 2 1 hours grams. 21.09 .90 .90 .90 grains. 55 60 50 53 grams. 4 9 -1 2 grams. 41 47 42 44 grams. -5 1 -4 -2 cals. 172 184 161 167 cals. 8 20 -3 3 2\ to 4J hours 4i to CJ hours 6| to 81 hours Total 218 14 174 -10 684 28 'Subject ate food in 28 minutes. 5Sample included amount for about 21 hours preceding eating of food. TABLE 194.— A. W. W., April 25, 1907. Sitting. (2-hour periods.) Butter and potato chips: Amounts, 85 grams butter, 104 grams potato chips; nitrogen, 1.05 grams; total energy, 1,285 cals. Fuel value: Total, 1,276 cals.; from protein, 2 p. ct.; from fat, 82 p. ct.; from carbohydrates, 16 cals. Basal values (March 15 and 21, 1907) : CO2, 50 grams; O-2, 41 grams; heat, 155 cals. Time elapsed since subject finished eating.1 Nitrogen in urine per 2 hours. Carbon dioxide. Oxygen. Heat. Total. Increase. Total. Increase. Total. Increase. 1 to 3 hours gram. 0.57 .53 .44 .44 grains. 53 54 51 51 grams. 3 4 1 1 grams. 43 43 44 42 grams. 2 2 3 1 cals. 165 161 154 155 cals. 10 6 -1 0 3 to 5 hours 5 to 7 hours 7 to 9 hours Total 209 9 172 8 635 15 Subject ate food in 26 minutes. J. J. C., March 12, 1910. — The experiment on this date was the first of a supplementary series with the butter and potato chips diet carried out in Boston three years after the Middletown experiments. The subject took but 38 grams of butter and 91 grams of potato chips; the results obtained are given in table 195. Although the basal value was determined on the same day as the values after food, and the general trend of the results was similar to that of the results obtained in the previous experiments, we do not feel justified in laying great emphasis 262 FOOD INGESTION AND ENERGY TRANSFORMATIONS. upon the data, owing to the general irregularity in muscular repose shown by this subject, especially in the sitting position. The experi- ment may be said, therefore, to give incomplete evidence as to the increment in the metabolism due to a predominatingly fat diet. TABLE 195. — J. J. C., March 12, 1910. Sitting. (1-hour periods.) Butter and. potato chips: Amounts, 38 grams butter, 91 grams potato chips; nitrogen, 0.76 gram; total energy, 798 cals. Fuel value: Total, 791 cals.; from protein, 2 p. ct. ; from fat, 79 p. ct. ; from carbohydrates, 19 p. ct. Nitrogen in urine, 0.30 gram per hour.1 Basal values (March 12, 1910): CO2, 24 grams; Oz, 20.5 grams; heat, 75 cals.; respiratory quo- tient, 0.86. Nitrogen in urine, 0.14 gram per hour. Time elapsed since subject finished eating. Carbon dioxide. Oxygen. Heat. Respiratory quotient. Total. Increase. Total. Increase. Total. Increase. 0 to 1 hour2 grams. 26.0 27.0 27.5 25.5 25.0 grams. 2.0 3.0 3.5 1.5 1.0 grams. 24.0 25.5 26.5 20.5 23.0 grams. 3.5 5.0 6.0 0.0 2.5 cals. 87 79 78 71 74 cals. 12 4 3 -4 -1 0.79 .78 .75 .91 .79 1 to 2 hours 2 to 3 hours . . . 3 to 4 hours . . . 4 to 5 hours Total 131.0 11.0 119.5 17.0 389 14 'Sample included amount for about 2 hours preceding eating of food. 2Subject finished eating 22 minutes after beginning of this period. The eating occupied 16 minutes. L. E. E., March 14, 1910. — A larger amount of butter was taken in this experiment than in the preceding experiment, 92 grams being eaten with 114 grams of potato chips. The detailed results are given in table 196. Although L. E. E. was a trained observer on the staff of the Nutrition Laboratory and accustomed to remaining very quiet, he was in this experiment distinctly restless. The increment in carbon- dioxide production was found in the first and third periods; the values for oxygen consumption and heat production were also irregular. For some as yet unexplained reason, the metabolism in the second and fourth periods was shown to be basal by all three factors. The total increment for the carbon-dioxide production was 6 grams, for the oxygen consumption 13 grams, and for the heat production 36 calories, thus confirming the evidence of the experiments previously discussed that the ingestion of a predominatingly fat diet has a positive effect upon the metabolism. J. R., March 21, 1910. — After the ingestion of 95 grams of butter and 92 grams of potato chips, slight increments were found in carbon- dioxide production throughout the 5 hours of the experiment and in most of the periods for heat production, with somewhat large incre- ments in oxygen consumption. The results of the experiment, which are given in detail in table 197, thus supply further proof as to the INGESTION OF FAT. 263 stimulating effect of a fat diet upon the metabolism. In the three experiments with the Boston calorimeter the last one with J. R. is the only one in which there was a noticeable increase in the pulse rate after the taking of food. The change was from 70 in the preliminary period to 73 after food. TABLE 196.— L. E. E., March 14, 1910. Sitting. (1-hour periods.) Butter and potato chips: Amounts, 92 grams butter, 114 grams potato chips; nitrogen, 0.69 gram; total energy, 1,518 cals. Fuel value: Total, 1,512 cals.; from protein, 1 p. ct.; from fat, 86 p. ct.; from carbohydrates, 13 p. ct, Nitrogen in urine, 0.47 gram per hour (in first three periods).1 Basal values (March 14, 1910) : CO2, 27 grams; Oa, 22 grams; heat,2 70 cals.; respiratory quotient, 0.88. Nitrogen in urine, 0.56 gram per hour. Time elapsed since subject finished eating. Carbon dioxide. Oxygen. Heat.2 Respiratory quotient. Total. Increase. Total. Increase. Total. Increase. 0 to 1 hour3 grams. 30.5 27.0 29.0 27.0 27.5 grains. 3.5 0.0 2.0 0.0 0.5 grams. 26.0 21.5 26.5 22.5 26.5 grams. 4.0 -0.5 4.5 0.5 4.5 cals. 85 67 83 71 80 cals. 15 -3 13 1 10 0.85 .92 .79 .88 .76 1 to 2 hours 2 to 3 hours 3 to 4 hours 4 to 5 hours Total 141.0 6.0 123.0 13.0 386 36 'Sample included amount for about 2 hours preceding the eating of food. 2Heat eliminated corrected for change in body-weight, but not for change in body-temperature. 'Subject finished eating 20 minutes after beginning of this period. The eating occupied 16 minutes. TABLE 197.— J. R., March 21, 1910. Sitting. (1-hour periods.) Butter and potato chips: Amounts, 95 grams butter, 92 grams potato chips; nitrogen, 0.85 gram; total energy, 1.273 cals. Fuel value: Total, 1,266 cals.; from protein, 2 p. ct. ; from fat, 87 p. ct, ; from carbohydrates, 11 p. ct. Nitrogen in urine, 0.36 gram per hour.1 Basal values (March 21, 1910) : CCh, 26 grams; O2, 21 grams; heat, 80 cals.; respiratory quotient, 0.89. Nitrogen in urine, 0.35 gram per hour. Time elapsed since subject finished eating. Carbon dioxide. Oxygen. Heat. Respiratory quotient. Total. Increase. Total. Increase. Total. Increase. 0 to 1 hour2 grams. 28.0 28.5 28.0 27.5 28.0 grams. 2.0 2.5 2.0 1.5 2.0 grams. 24.5 24.5 24.5 22.0 26.5 grams. 3.5 3.5 3.5 1.0 5.5 cafe. 85 78 83 81 84 cals. 5 -2 3 1 4 0.84 .85 .83 .91 .77 1 to 2 hours 2 to 3 hours . . 3 to 4 hours 4 to 5 hours Total 140.0 10.0 122.0 17.0 411 11 Sample included amount for about 3f hours without food preceding experiment. 2Subject finished eating 17 minutes after beginning of this period. The eating occupied 9 minute^. 264 FOOD INGESTION AND ENERGY TRANSFORMATIONS. CONCLUSIONS REGARDING EFFECT OF INGESTION OF FAT. Although the experiments in this series can hardly be considered as ideal, being open to the criticisms raised in their discussion, yet the preponderance of evidence clearly shows that the ingestion of fat in the form of cream, or butter with potato chips, has a positive influence upon the metabolism. This is not in accordance with the results of Koraen,1 who found no increase in the metabolism after the ingestion of about 66 grams of fat. Aside from a few experiments in which a depression in the metabolism below the basal value was found in the latter part of the experimental period, we obtained no evidence sup- porting the general view of Gigon that the ingestion of fat results in a depression of the metabolism (see page 40). Gigon's most interesting and suggestive explanation of his experiments, namely, that the inges- tion of a fat diet (olive oil) caused a depression of the digestive activity which is present even in the post-absorptive condition, finds no sup- port in the results of our experiments. It should be borne in mind that Gigon used a pure fat, while all of our experiments were carried out with materials containing a certain proportion of other nutrients. It is difficult, however, to believe that the starch in the potato chips or the small amount of protein and lactose in the cream could have counterbalanced the effect observed by Gigon. We are inclined to consider that the depression in the metabolism reported by him was more apparent than real and that his findings are due to the faulty use of a basal value, determined a long time before the experiments were made. By the use of this value he assumed a constancy in basal metabolism which, while justifiable when severe muscular work is to be performed, is hardly permissible when small increments in the metabolism are to be expected, such as those following the ingestion of small amounts of food or even large amounts of fat.2 We may therefore conclude that the ingestion of fat produces a positive increment in the metabolism. Although the increment is considerably less than that observed with an equivalent amount of energy in either carbohydrate or protein, it is nevertheless a factor that must not be neglected in a consideration of the influence of the ingestion of food upon the metabolism. We are in full accord with Gigon in believing that a study of the effect on the metabolism of ingesting pure fat is highly desirable and regret that more experiments with olive oil or other pure fats were not included in our series. Koraen, Skand. Arch. f. Physiol., 1901, 11, p. 176. See, also, p. 32 of this publication. 2Personal acquaintance with Professor Gigon and a full appreciation of his high scientific con- ceptions of the importance of physiological research have led us to attempt to communicate with him personally regarding the adverse criticisms which we have felt it necessary to make in this report. While an acknowledgment of the receipt of the letter has been made, he states that it has been impossible for him as yet to take up in detail any of the criticisms which we raise, although he promises to send a letter to us shortly. Undoubtedly war conditions have made it impracti- cable for him to do this. It is a matter of great regret to us that we have been obliged to go to press without personal information regarding the criticisms here raised, so that if we are in error or have misinterpreted his attitude wo might modify our expressions in such way as to fit the case more exactly. INGESTION OF PROTEIN DIETS. 265 INGESTION OF PREDOMINATINGLY PROTEIN DIETS. No single nutrient, when ingested, produces so great an effect upon the metabolism as protein does. In fact, the earlier observations, par- ticularly those made by Rubner and Magnus-Levy with dogs and man, appeared to show that protein was the only nutrient which measurably increased the metabolism. At the time of beginning our study on the effect of food upon the metabolism, the varieties of pure protein avail- able were relatively limited. Accordingly the largest number of experi- ments were made with beefsteak, for though this food material was not a pure protein, it was palatable and easily obtained. Furthermore, as the beefsteak given the subject was freed from all visible fat, it was assumed that the amount of fat ingested would play but a small part in the metabolism. In a number of the beefsteak experiments small amounts of bread or potato chips were also taken. In some of the observations approximately pure protein materials were used, these being gluten, plasmon, and in the later experiments in Boston, glidine. The gluten and plasmon were both taken with skim milk. In the experiments with relatively pure protein and in a large pro- portion of the beefsteak experiments the observations were made with the calorimeter. While these experiments do not by any means fulfill the demands of the technique at the present time, they do represent the first attempt with man to determine by direct calorimetry the influence upon the metabolism of the ingestion of protein; conse- quently they are discussed in some detail. One defect in the plan of experimenting for all of the Middletown calorimeter experiments and for the majority of the Boston calorimeter experiments is the fact that the basal values and the values after the ingestion of protein were not determined on the same day. Although the experiments with gluten and skim milk and plasmon and skim milk were made in 1906, while those with beefsteak were not begun until 1907, it seems desirable to consider first the data with the single food materials, especially as so large a number of observations were made with beefsteak. BEEFSTEAK. MIDDLETOWN CALORIMETER EXPERIMENTS. The four Middletown experiments, which were made with but two subjects, are best discussed according to the amounts of food ingested, as they were planned for comparison purposes. In the first pair of experiments, those with A. H. M. on April 5, 1907, and A. W. W. on April 6, 1907, a large amount of beefsteak was taken, the measurements of the metabolism beginning about an hour after the subject had finished eating. In the second set of observations with the same sub- 266 FOOD INGESTION AND ENERGY TRANSFORMATIONS. jects on May 24 and 25, 1907, the amount of food used was about half that taken in the earlier series; the metabolism measurements began approximately 15 minutes after the eating of the beefsteak. In all of these experiments the periods were 2 hours long. Statistical data regarding the experiments, not included in the tables or the discussion, are as follows: A, H. M., 9h29m a. ra. to 5h29m p. m., April 5, 1907. 65.9 kilograms.— Took enema without result; drank water 9h37m a. m., Ilh34m a. m., 12h13rn p. m., Ih32m p. m. (total amount, 325 grams). Urinated 7h15m, 9h35m, Ilh31m a. m., Ih32m, 3h30, 5h29m p. m. ; slight desire to defecate in later periods. First two periods very quiet, reading most of time; in last two periods somewhat more active but still comparatively quiet; read but little in these periods. Body-temperature: 36.87°, 36.76°, 36.70°, 36.82°, 36.85° C. Pulse rate, 64; respiration rate, 18. Nitrogen in urine per 2 hours 7h15m a. m. to 9h35m a. m., 3.23 grams. A. W. W., 9h08m a. m. to 5*08m p. m., April 6, 1907. 58.8 kilograms.— Enema at 7h10m a. m., feeling of heaviness and fullness after eating; drowsy during first part of experiment; studied first three periods, translating with use of vocabulary, with consequently more minor activity than usual; fourth period very quiet; middle of experiment, also throughout last period, felt warm and perspired. Drank water at beginning of every period (846 grams in all) ; urinated 8h09m a. m. and every period of experiment. Body-temperature: 36.77°, 36.70°, 36.69°, 36.79°, 36.79° C. Pulse rate, 66; respiration rate, 21. A. H. M., 9h34m a. m. to 5h%4m p. m., May 24, 1907. 65.9 kilograms.- Enema at 7h15m a. m. without result. Quiet in experiment; read greater part of time; idle last hour. Drank water before experiment (175 grams); at end of first period (31 grams). Tired at end of experiment. Urinated 7h10m and Ilh30m a. m., 3h30m and 5h50m p. m. Body-temperature: 36.40°, 36.39°, 36.40°, 36.12°, 36.30° C. Pulse rate, 63; respiration rate, 18. A. W. W., 8h17m a. m. to 4h17m p. m., May 25, 1907. 56.7 kilograms.- Very quiet throughout experiment ; urinated 6h30m a. m. and in each of three last periods ; drank water at beginning of every period (787 grams in all) . Pulse rate, 64; respiration rate, 19. DISCUSSION OF EXPERIMENTS. A. H. M., April 5, 1907. — The subject consumed 777 grams of beef- steak in 1^ hours; the nitrogen content of the food was 35.68 grams. The basal values used for comparison were obtained from two experi- ments made about a month previous to the experiment with beefsteak. This man had been used for a large number of experiments and was usually very quiet and satisfactory in every way. While there was not complete muscular repose throughout the experiment, the subject sat quietly in a chair, reading most of the time. The urine was collected in periods of 2 hours for the purpose of obtaining an indication of the course of the nitrogen excretion. The results of the experiment are given in table 198 and show a striking increment in all the factors of metabolism. The carbon- dioxide production increased 12 to 20 grams, the oxygen consumption 8 to 16 grains, and the heat production 29 to 41 calories. The res- INGESTION OF PROTEIN DIETS. 267 piratory quotients remained relatively constant throughout the whole experimental period, averaging 0.85. Both carbon-dioxide production and oxygen consumption showed a maximum increase in the first 2-hour period, while that for heat production occurred in the third period. The maximum percentage increases were 39 per cent for the TABLE 198.— A. H. M., April 5, 1907. Sitting. (2-hour periods.) Beefsteak: Amount, 777 grams; nitrogen, 35.68 grams; total energy, 1,617 cals. Fuel value: Total, 1,305 cals.; from protein, 70 p. ct. ; from fat, 30 p. ct. Basal values (March 6 and 9, 1907): CO2, 51 grams; O2, 46 grams; heat, 164 cals. Carbon dioxide. Oxygen. Heat. Time elapsed Nitro- Respi- since subject gen in Increase. Increase. Increase. ratory finished urine quo- eating.1 per 2 hours. Total. Total. Per cent. Total. Total. Per cent. Total. Total. Per cent. tient. grains. grams. grams. grams. grams. cals. cals. 1 to 3 hours 4.00 71 20 39 62 16 35 195 31 19 0.84 3 to 5 hours 2.08 64 13 25 54 8 17 193 29 18 .87 5 to 7 hours 2.38 69 18 35 59 13 28 205 41 25 .85 7 to 9 hours 3.03 63 12 24 55 9 20 199 35 21 .83 Total . . 267 63 31 230 46 25 792 136 21 ^Subject ate beefsteak in lj hours. carbon-dioxide production, 35 per cent for the oxygen consumption, and 25 per cent for the heat production. As there was a large increment in the last period, it is quite clear that the influence of the beefsteak on the metabolism had not ceased at the end of the experiment. The computation of the total increment and the total percentage increase can therefore have but little quantitative value, but as the figures have a general interest they are given in table 198. There was a total increment of 63 grams in carbon-dioxide production, 46 grams in oxygen consumption, and 136 calories in heat production. A. W. W., April 6, 1907. — Essentially the same amount of food was taken in this experiment as in that on the preceding day with A. H. M., ?'. e., 755 grams, with a total nitrogen content of 34.67 grams. The results, including the data for the nitrogen excretion, are given in table 199. The basal values used were averages of the results obtained in two experiments made from 2 to 3 weeks previous to the experiment with beefsteak. A noticeable increase in carbon-dioxide production occurs in all periods, the maximum amount being obtained in the third period. The maximum oxygen consumption appeared in the second period, while the maximum heat production was found in the fourth period. The course of the respiratory quotient was somewhat irregu- lar. Since there are material increases in the fourth period, it is evident that here again we have not obtained the total effect of the 268 FOOD INGESTION AND ENERGY TRANSFORMATIONS. TABLE 199.— A. W. W., April 6, 1907. Sitting. (2-hour periods.) Beefsteak: Amount, 755 grams; nitrogen, 34.67 grams; total energy, 1,571 cals. Fuel value: Total, 1,268 cals.; from protein, 70 p. ct. ; from fat, 30 p. ct. Basal values (March 15 and 21, 1907) : COz, 50 grams; O2, 41 grams; heat, 155 cals. Carbon dioxide. Oxygen. Heat. Time elapsed Nitro- Respi- since subject gen in Increase. Increase. Increase. ratory unne quo- eating.1 per 2 hours. Total. Total. Per cent. Total. Total. Per cent. Total. Total. Per cent. tient. grams. grams. grams. grams. grams. cals. cals. 1 to 3 hours 22.08 60 10 20 47 6 15 152 -3 -2 0.93 3 to 5 hours 2.52 62 12 24 57 16 39 181 26 17 .79 5 to 7 hours 3.11 63 13 26 52 11 27 187 32 21 .88 7 to 9 hours 3.65 60 10 20 53 12 29 192 37 24 .82 Total 245 45 23 209 45 27 712 92 15 'Subject ate beefsteak in 54 minutes. 2Sample included amount for about 1 hour following the eating of beefsteak. food upon the metabolism in the 8 hours of the experimental period, and the experiment is therefore incomplete in this respect. It was of course possible to have made the experiment of 24 hours' duration, subdividing it into three 8-hour periods, but the main purpose of our experimenting was to study the maximum effect in the earlier stages of digestion, and the data are sufficient for this purpose. Thus we find that the maximum increment for carbon-dioxide production was 26 per cent, for oxygen consumption 39 per cent, and for heat produc- tion 24 per cent. One anomalous value appears in the results — that is, the slightly negative value found for heat production in the first period. This may be taken as essentially the basal value, although undoubtedly an error in direct calorimetry may have accounted for the fact that no increment was noted. The general picture shown in these results is not unlike that of the preceding experiment, namely, a decided increase in all of the factors of the metabolism. The fact that the high incre- ments continued even into the last period indicates that the effect of food ingestion had not begun to decrease at the end of the experiment. A. H. M., May 24, 1907. — Approximately half the amount of beef- steak used in the experiment with this subject on April 5, 1907, was taken in the second experiment, the amount in this case being 384 grams, with a nitrogen content of 17.63 grams. The basal values used in the first experiment were likewise employed here. The data regarding metabolism, together with those for nitrogen excretion, are given in table 200. An increase in carbon-dioxide production, oxygen consumption, and heat production occurred in the first three periods, with a return to the basal metabolism in the fourth period. We doubtless have here, therefore, the total effect of the ingestion INGESTION OF PROTEIN DIETS. 269 of this amount of beefsteak. The maximum increment occurred in the second period with all three factors, the percentage maximum for carbon-dioxide production being 27 per cent, for oxygen consumption 20 per cent, and for heat production 16 per cent. TABLE 200. — A. H. M., May 24, 1907. Sitting. (2-hour periods.) Beefsteak: Amount, 384 grams; nitrogen, 17.63 grams; total energy, 799 cals. Fuel value: Total, 644 cals.; from protein, 70 p. ct. ; from fat, 30 p. ct. Basal values (March 6 and 9, 1907): CCh, 51 grams; O2, 46 grams; heat, 164 cals. Time elapsed since subject Nitrogen in urine Carbon dioxide. Oxygen. Heat.2 Respira- finished eating.1 per 2 hours. Total. Increase. Total. Increase. Total. Increase. tory quotient. grams. grams. grams. grams. grams. cals. cals. i to 2J hours 31.61 60 9 48 2 188 24 0.91 2ito4J hours 2.45 65 14 55 9 191 27 .85 4i to 6j hours 2.45 55 4 52 6 183 19 .78 6i to 8J hours 1.75 52 1 46 0 164 0 .82 Total . . . 232 28 201 17 726 70 Subject ate beefsteak in lj hours. 2Heat eliminated corrected for change in body-weight, but not for change in body-temperature. 3Sample included amount for about j hour without food and for If hours with food preceding this period. A. W. W ., May 25, 1907.— Although made with a different subject, this is essentially a duplicate of the experiment on May 24, 1907, as the amount of beefsteak ingested (373 grams) is practically the same in both experiments and approximately one-half the amount eaten by A. W. W. in the experiment on April 6, 1907. The nitrogen con- tent of the food was 18.62 grams. The results are given in table 201, and show the same general picture as the data given in table 200, i. e., an increment in the first three periods with a return to the basal metab- olism in the fourth period. A singular fact to be noted is that the maximum effect for all three factors was observed in the third period, although this immediately preceded the return to the basal level. The total increment in carbon-dioxide production was 20 grams, in oxygen consumption 32 grams, and in heat production 45 calories. The total increment in heat production is much less than that found in the com- parison experiment with A. H. M.; the increments for carbon-dioxide production and oxygen consumption also vary considerably in the two experiments. From the results of these experiments it is evident that the ingestion of approximately 375 grams of beefsteak results in an increased metabolism which is essentially completed at the end of 6 hours, as the values obtained for the last 2-hour period of both 8-hour experiments indicate that the basal level for the metabolism had again been reached. 270 FOOD INGESTION AND ENERGY TRANSFORMATIONS. TABLE 201.— A. W. W., May 25, 1907. Sitting. (2-hour periods.) Beefsteak: Amount, 373 grams; nitrogen, 18.62 grams; total energy, 1,144 cals. Fuel value: Total, 981 cals.; from protein, 49 p. ct. ; from fat, 51 p. ct. Basal values (March 15 and 21, 1907) : CO2, 50 grams; 62, 41 grams; heat, 155 cals. Time elapsed since subject Nitrogen in urine Carbon dioxide. Oxygen. Heat.2 Respira- finished per tory eating. 2 hours. Total. Increase. Total. Increase. Total. Increase. quotient. grams. grams. grams. grams. grams. cals. cals. J to 2j hours 30.92 57 7 51 10 171 16 0.81 2 i to 4J hours 1.61 55 5 51 10 171 16 .79 4j to 6} hours 1.95 59 9 54 13 173 18 .80 6i to 8J hours 1.75 49 -1 40 -1 150 -5 .87 Total .... 220 20 196 32 665 45 Subject ate beefsteak in 23 minutes. 2Heat eliminated corrected for change in body-weight, but not for change in body-temperature. 'Sample included amount for about 1 hour preceding eating of beefsteak. BOSTON CALORIMETER EXPERIMENTS. Following the construction of the respiration calorimeters1 in the Nutrition Laboratory, a series of five experiments subsequent to the ingestion of beefsteak was made with the chair calorimeter, beginning on December 4, 1908. The first two were 8-hour experiments, but the last three experiments continued for only 5 or 6 hours. The observa- tions were made in 1-hour periods in all cases. The statistical data not included in the tables or discussion of these experiments are given in the following paragraphs; no additional data were available for L. E. E.: J. R., 9h45m a. m. to 5h45m p. m., December 4, 1908. 66.2 kilograms.- Drank water at 10 a. m. (198 grams); urinated 7, 9h57m, Ilh58m a. m., 2, 3h59m, and 5h55m p. m. Head ached after 2h30m p. m. Pulse rate, 62; these records sometimes difficult to obtain and at times pulse rate very low. No records could be obtained last half hour. Respiration rate, 17; but one record obtained after 4h45m p. m. Nitrogen in urine per hour 7 a. m. to 9h57m a. m., 0.48 gram. F. M. M., 9h01m a. m. to 5h01m p. m., December 10, 1918. 59.8 kilograms.- In seventh period showed tendency to fall asleep; instructed to ring signal bell every five minutes. Urinated 7h05m, 9h01m, Ilh01m a, m., Ih01m, 3h01m, and 5h01m p. m. Drank water at 9h01m a. m., Ilh01m a. m., 2h01m p. m., and 4h01m p. m. (total amount, 998 grams). Pulse rate, 52. Nitrogen in urine per hour 7h05m a. m. to 9h01m a. m., 0.48 gram. F. M. M., 8h55m a. m. to 2h55m p. m., December 23, 1908. 59.8 kilograms.- Did not eat all beefsteak provided, owing to pain in stomach; feared that a larger amount might increase pain and prevent experiment. Urinated and defecated at 7h30m a. m., also urinated at 11 a. m., 1 p. m., and 3 p. m. ; drank water at 9 a. m., 11 a. m., and 1 p. m. (681 grams in all). Body-temperature: 36.75°, 36.95°, 36.79°, 36.69°, 36.66°, 36.72°, 36.85° C. Pulse rate, 56. 'Benedict and Carpenter, Carnegie Inst. Wash. Pub. No. 123, 1910. INGESTION OF PROTEIN DIETS. 271 F. M. M., 9h26m a. m. to 3h06m p. m., January 20, 1910. 01.5 kilograms.- Third period lengthened owing to unaccountable variations in the temperature conditions at end of hour. Nitrogen in urine per hour 6h45m a. m. to 10h30m a. m., 0.85 gram. DISCUSSION OF EXPERIMENTS. /. R., December 4, 1908. — The basal value for this experiment was determined on December 3. After the ingestion of 418 grams of beef- steak on December 4, having a nitrogen content of 15.30 grams, an in- crement in the carbon-dioxide production was noted in all of the eight periods, although the values had nearly reached the basal level in the last period (see table 202) . Noticeable increments in the oxygen con- sumption were also found throughout the experiment ; even in the eighth hour there was a consumption of 4 grams more than the basal re- quirement. The heat production was likewise increased in all of the periods. The maximum increments for carbon-dioxide production and oxygen consumption were noted in the third hour of the experiment, while that for heat production was found in the first period. The total increment, both in carbon-dioxide production and in oxygen consump- tion, was 31.5 grams; in heat production it was 104 calories. As the basal level had not been reached at the end of the experiment, the stimulus of the beefsteak was apparently still effective. The large ex- cretion of nitrogen in the urine, with a total increment of 7.80 grams for the 8 periods, indicates a considerable katabolism of protein during the experiment. TABLE 202. — J. R., December 4, 1908. Sitting. (1-hour periods.) Beefsteak: Amount, 418 grams; nitrogen, 15.30 grams; total energy, 737 cals. Fuel value: Total, 603 cals.; from protein, 65 p. ct.; from fat, 35 p. ct. Based values (December 3, 1908): CO2, 26.5 grams; O2, 23.5 grams.; heat,1 74 cals. Nitrogen in urine, 0.38 gram per hour (December 4, 1908). Carbon dioxide. Oxygen. Heat.1 Time elapsed since subject Nitro- gen in Respi- ratory Increase. Increase. Increase. finished eating. urine per hour. Total. Total. Total. quo- tient. Total. Per cent. Total. Per cent. Total. Per cent. grams. grams. grams. grams. grams. cals. cals. 1$ to 2} hours 0.85 33.0 6.5 25 28.5 5.0 21 95 21 28 0.86 2} to 3J hours .85 30.5 4.0 15 27.0 3.5 15 84 10 14 .81 31 to 41 hours .96 33.5 7.0 26 32.5 9.0 38 93 19 26 .75 41 to 51 hours .96 31.0 4.5 17 26.5 3.0 13 87 13 18 .85 51 to 61 hours 1.10 30.5 4.0 15 26.0 2.5 11 86 12 16 .85 61 to 71 hours 1.10 28.5 2.0 8 25.5 2.0 9 84 10 14 .82 71 to 81 hours .99 28.5 2.0 8 26.0 2.5 11 83 9 12 .80 8} to 91 hours .99 28.0 1.5 6 27.5 4.0 17 84 10 14 .74 Total . 243.5 31.5 15 219.5 31.5 17 696 104 18 .... *Heat eliminated corrected for change in body-weight, but not for change in body-temperature. 272 FOOD INGESTION AND ENERGY TRANSFORMATIONS. F. M. M., December 10, 1908. — A somewhat smaller amount of beef- steak was taken by this subject than that taken by the subject of the preceding experiment, the amount in this case being 217 grams, with a nitrogen content of 9.97 grams. As in the experiment with J. R., the urine was collected every 2 hours. The results of the experiments are given in table 203, from which it is seen that the increase in carbon- dioxide production in each of the first three periods amounted to 3 grams or over; in the 5 hours following it was practically 1 gram above the basal value. Since a possible error of 1 or 1.5 grams in the basal value is permissible, one may conclude from the values for carbon- dioxide production alone that the basal value was reached at the end of the third hour. Irregular increments, which are difficult to explain, were found for oxygen consumption throughout the whole experiment. The maximum increase was 7 grams in the first hour and the lowest, 0.5 gram, in the fifth period. Somewhat large increments were noted in the sixth, seventh, and eighth hours which indicate that if the experi- mental technique were accurate, the basal level was not reached at the end of the experiment. A measurable increment in heat produc- tion occurred in the first 3 hours, but subsequently irregular values were found, with an increase of 5 calories in the sixth period, followed by a decrease of 6 calories in the seventh period, this variation possibly indicating a compensation. From the standpoint of direct calo- rimetry, the experiment can hardly be called successful. If we base our conclusion upon the values obtained for carbon-dioxide excretion and heat production, it is probable that the basal level was reached in approximately the fourth hour. The respiratory quotients indicate a leakage of air in the last three periods. TABLE 203.—^. M. M., December 10, 190S. Sitting. (1-hour periods.) Beefsteak: Amount, 217 grams; nitrogen, 9.97 grams; total energy, 451 cals. Fuel value: Total, 364 cals.; from protein, 70 p. ct.; from fat, 30 p. ct. Basal values (December 9, 1908) : CO2, 25 grams; Oa, 21 grams; heat, 77 cals. Time elapsed since subject Nitrogen Carbon dioxide. Oxygen. Heat.1 Respira- finished in urine tory eating. per hour. Total. Increase. Total. Increase. Total. Increase. quotient. gram . grams. grams. grams. grams. cals. cals. H to21 hours 0.73 30.5 5.5 28.0 7.0 91 14 0.79 2|to3J hours .73 29.5 4.5 22.5 1.5 79 2 .94 31 to 4J hours .79 28.0 3.0 26.5 5.6 85 8 .77 41 to 5 i hours .79 26.0 1.0 24.5 3.5 78 1 .77 51 to 61 hours .(17 25.5 0.5 21.5 0.5 75 -2 .85 61 to 71 hours .67 26.5 1.5 26.0 5.0 82 5 .75 71 to 81 hours .60 26.0 1.0 25.0 4.0 71 -6 .75 81 to 91 hours .60 26.5 1.5 24.5 3.5 79 2 .78 Total 218.5 18.5 198.5 30.5 640 24 'Heat eliminated corrected for change in body-weight, but not for change in body-temperature. INGESTION OF PROTEIN DIETS. 273 F. M. M., December 23, 1908. — In this second experiment with F. M. M. 208 grams of beefsteak, with a nitrogen content of 9.55 grams, were ingested, this being approximately the same as in the experiment on December 10. The observations continued for only 6 hours, the urine being collected in 2-hour periods as before. Increments in car- bon-dioxide production were noted in the first three periods, also in oxygen consumption. (See table 204.) Irregular values were ob- tained for both factors thereafter. This irregularity was also shown in heat production, as increments were obtained for the first and third periods and a basal value in the second period. As the irregularity in values is very pronounced, one may regard it as probable that the total effect of the beefsteak was obtained in the first 3 or possibly 4 hours, as also in the experiment with this subject on December 10, 1908. TABLE 204.— F. M. M., December 23, 1908. Sitting. (1-hour periods.) Beefsteak: Amount, 208 grams; nitrogen. 9.55 grams; total energy, 433 cals. Fuel value: Total, 349 cals.; from protein, 70 p. ct.; from fat, 30 p. ct. Basal values (December 9 to 29, 1908) : CO2, 25.5 grams; 62, 22.5 grama; heat,1 75 cals. Time elapsed since subject finished eating. Nitrogen in urine per hour. Carbon dioxide. Oxygen. Heat.1 Respira- tory quotient. Total. Increase. Total. Increase. Total. Increase. gram. grams. grams. grams. grams. cals. cals. 1 to 2 hours . . . 20.57 30.0 4.5 24.5 2.0 80 5 0.88 2 to 3 hours . . . 2.57 28.5 3.0 24.5 2.0 75 0 .84 3 to 4 hours . . . .61 30.0 4.5 24.0 1.5 82 7 .91 4 to 5 hours . . . .61 25.0 -0.5 21.0 -1.5 77 2 .86 5 to 6 hours . . . .65 28.0 2.5 24.0 1.5 78 3 .84 6 to 7 hours . . . .65 26.0 0.5 22.5 0.0 75 0 .83 Total . . 167.5 14.5 140.5 5.5 467 17 lHeat eliminated corrected for change in body-weight, but not for change in body- temperature. 2Sample included amount for about 1? hours preceding the first period. F. M. M., January 20, 1910. — In the experiment recorded in table 205, only 132 grams of beefsteak were eaten, with a nitrogen content of 6.05 grams. Increments in carbon-dioxide production and oxygen con- sumption were noted in the first 2 hours; thereafter values below the basal value were observed. The heat production showed an increment in the first five of the six periods. The only conclusion which can be drawn from this experiment is that the effect of the ingestion of beef- steak probably continued for 2 hours. The basal values used in this experiment were the average of results obtained in four experiments made within a month of the experiment with beefsteak. These ap- peared to be the most suitable basal values available, but the irregu- larities in the increments, as well as the appearance of values lower than basal, serve to accentuate the difficulties of measuring slight increases when the basal value is uncertain. 274 FOOD INGESTION AND ENERGY TRANSFORMATIONS. TABLE 205. — F. M. M., January SO, 1910. Sitting. (1-hour periods.) Beefsteak: Amount, 132 grams; nitrogen, 6.05 grams; total energy, 274 cals. Fuel value: Total, 221 cals.; from protein, 70 p. ct.; from fat, 30 p. ct. Basal values (January 31 to February 19, 1910): COa, 26.5 grams; Os, 23 grams; heat,1 80 cals. Time elapsed since subject finished eating. Nitrogen in urine per hour. Carbon dioxide. Oxygen. Heat.1 Respira- tory quotient. Total. Increase. Total. Increase. Total. Increase. gram. grains. grams. grams. grams. cals. cals. li to 2 1 hours 20.85 30.0 3.5 25.0 2.0 85 5 0.88 2J to 3J hours . . . 29.0 2.5 25.0 2.0 84 4 .86 r .... 24.0 -2.5 22.0 -1.0 83 3 .81 3j to 6 hours .... 24.0 -2.5 22.0 -1.0 83 3 .81 I .... 24.0 -2.5 22.0 -1.0 83 3 .81 6 to 7 hours .... 25.5 -1.0 22.0 -1.0 74 -6 .85 Total .... 3149.5 3-0.5 3129.5 3-1.0 3463 310 1Heat eliminated corrected for change in body-weight, but not for change in body-temperature . 2Sample included amount for about li hours without food and for 1| hours with food preceding this period. 3Total amounts for the actual duration of the experiment, i. e., 5h40m. L. E. E., January 17, 1910. — But 163 grams of beefsteak, with a nitrogen content of 7.20 grams, were eaten by the subject in this experi- ment ; the values obtained thereafter are given in table 206. Consider- able increments in the carbon-dioxide production, oxygen consump- tion, and heat production were found throughout the whole experiment. Unfortunately it is necessary to use for basal values the results obtained in three experiments several months later; the base-line used may therefore be somewhat too low. It is not impossible that somewhat smaller increments would have been obtained than appear here if the TABLE 206.— L. E. E., January 17, 1910. Sitting. (1-hour periods.) Beefsteak: Amount, 163 grams; nitrogen, 7.20 grams; total energy, 308 cals. Fuel value: Total, 245 cals.; from protein, 75 p. ct. ; from fat, 25 p. ct. Basal values (March 14 to May 11, 1910): CO2, 25.5 grams; O2, 21.5 grams; heat,1 76 cals. Time elapsed since subject finished eating. Carbon dioxide. Oxygen. Heat.1 Respiratory quotient. Total. Increase. Total. Increase. Total. Increase. 2 J to 3 i hours grams. 28.5 29.0 27.5 27.0 28.0 grams. 3.0 3.5 2.0 1.5 2.5 grams. 24.0 24.5 24.5 25.5 26.5 grams. 2.5 3.0 3.0 4.0 5.0 cals. 89 83 86 81 88 cals. 13 7 10 5 12 0.86 .85 .82 .78 .76 3 \ to 4 J hours 4i to 5J hours 5 i to 6J hours 61 to 71 hours Total 140.0 12.5 125.0 17.5 427 47 1Heat eliminated corrected for change in body-weight, but not for change in body-temperature INGESTION OF PROTEIN DIETS. 27 basal value had been determined on the experimental day, but since the experiment is made on much the same plan as those in other labora- tories, it is included in this discussion. Disregarding the high values obtained in the last period, the only conclusion which can be drawn from these imperfect data is that there was a positive increment in the metabolism for at least 3 hours as a result of ingestion of this amount of beefsteak. BEEFSTEAK AND SMALL AMOUNTS OF OTHER FOOD MATERIALS. In addition to the calorimeter experiments in which beefsteak alone was eaten, a number of experiments were made in which the diet included small amounts of bread or potato chips. The fact that these small quantities of other food materials were taken will not, however, materially interfere with the use of the results for comparison with those obtained when only beefsteak was given. Emphasis has already been laid upon the fact that the beefsteak was by no means a pure pro- tein material and contained a relatively large amount of fat, approxi- mately 30 to 40 per cent of the fuel value in most of the experiments previously discussed being derived from this substance. The chair calorimeter in Boston was used in all of the experiments but one, the exception being an experiment with beefsteak and potato chips in which the bed calorimeter was used. BEEFSTEAK AND BREAD. Three calorimeter experiments with beefsteak and bread were made, all with one subject. Approximately 200 to 250 grams of beefsteak were taken with 24 to 50 grams of bread. The statistical data regard- ing these experiments, not included in the tables or in the discussion, are given in the following paragraphs : F. M. A/., 10h14m a. m. to 3^1 4m p. m., January 1 1 , 1910. 60.4 kilograms.- Moved about considerably in first period and at end of period was swinging back and forth in chair. Urinated 7h30m a. m., 10h20m a. m., 3h25m p. m. Body-temperature: 36.76°, 36.71°, 36.85°, 36.86°, 36.83°, 36.99° C. F. M. M., 9h£8m a. m. to 2h28m p. m., January 13, 1910. — Nitrogen in urine per hour 7h30m a. m. to 12h57m p. m., 0.86 gram. F. M. M., 9*24m a. m. to 2*24™ p. m., January 14, 1910— Subject in ner- vous and depressed condition before entering apparatus from causes having no connection with experiment. Nitrogen in urine per hour 7h40m a. m. to Ih36m p. m., 0.74 gram; Ih36m p. m. to 2h35m p. m., 0.78 gram. DISCUSSION OF EXPERIMENTS. F. M. M., January 11, 1910. — The results of the experiment on this date are recorded in table 207. The food taken consisted of 246 grams of beefsteak and 50 grams of bread, with a nitrogen content of 10.70 grams. But one collection of urine was made for the experimental 276 FOOD INGESTION AND ENERGY TRANSFORMATIONS. period, the nitrogen excretion being 0.52 gram per hour. The incre- ment in carbon-dioxide production in the first 4 hours of this 5-hour experiment was considerable. Both the oxygen consumption and heat production were likewise above the basal requirements. A total incre- ment of 13.5 grams was found in both carbon-dioxide production and oxygen consumption, and in heat production of 44 calories. While in all probability the addition to the diet of the small amount of carbo- hydrate in bread affected slightly the carbon-dioxide production, nevertheless the ingestion of the beefsteak was undoubtedly the main cause of the increment noted with all three factors. TABLE 207.— F. M. M., January 11, 1910. Sitting. (1-hour periods.) Beefsteak and bread: Amounts, 246 grams beefsteak, 50 grams bread; nitrogen, 10.79 grams; total energy, 574 cats. Fuel value: Total, 480 cals. ; from protein, 58 p. ct. ; from fat, 20 p. ct.; from carbohydrates, 22 p. ct. Nitrogen in urine, 0.52 gram per hour.1 Basal values (January 31 to February 19, 1910): CO2, 26.5 grams; Oj, 23 grams; heat,2 80 cals. Time elapsed Carbon dioxide. Oxygen. Heat. since subject Respiratory finished quotient. eating. Total. Increase. Total. Increase. Total. Increase. grams. grams. grams. grams. cals. cals. 21 to 31 hours 30.5 4.0 27.5 4.5 89 9 0.81 31 to 4J hours 30.0 3.5 24.5 1.5 93 13 .89 4J to 51 hours 29.0 2.5 25.0 2.0 89 9 .84 51 to 61 hours 29.0 2.5 27.5 4.5 83 3 .77 61 to 71 hours 27.5 1.0 24.0 1.0 90 10 .84 Total . . . 146.0 13.5 128.5 13.5 444 44 'Nitrogen in an earlier sample for one-half hour before food and 2j hours after food \va,s 1.11 grams per hour. 2Heat eliminated corrected for change in body-weight, but not for change in body-temperature. F. M. M., January 12, 1910. — The amounts of both beefsteak and bread eaten before this experiment were somewhat smaller than on the previous day, being 199 grams and 38 grams, respectively, with a nitrogen content of 8.91 grams. There was a marked increase in the carbon-dioxide production in the first two periods, which was possibly due in part to the carbohydrate material. The significant increase in the oxygen consumption and heat production also occurred in the first two periods. It would appear, therefore, from this experiment that the influence of the beefsteak and bread upon the metabolism was practically at an end at the conclusion of the second 1-hour period. The nitrogen excretion was measurably greater than in the first experi- ment of the series, indicating a larger katabolism of protein. The results of the experiment are given in table 208. F. M. M.. January 14, 1910. — With 201 grams of beefsteak only 24 grams of bread were eaten in the experiment on this date, correspond- INGESTION OF PROTEIN DIETS. 277 TABLE 208.— F. M. M., January 12, 1910. Sitting. (1-hour periods.) Beefsteak and bread: Amounts, 199 grams beefsteak, 38 grams bread; nitrogen, 8.91 grams; total energy, 493 cals. Fuel value: Total, 415 cals.; from protein, 55 p. ct. ; from fat, 25 p. ct. ; from carbohydrates 20 p. ct. Nitrogen in urine, 0.86 gram per hour.1 Basal values (January 31 to February 19, 1910) : COj, 26.5 grams; 62, 23 grams; heat,2 80 cals. Time elapsed Carbon dioxide. Oxygen. Heat.2 since subject Respiratory finished quotient. eating. Total. Increase. Total. Increase. Total. Increase. grams. grams. grams. grams. cals. cals. 1 to 2 hours. . . 33.5 7.0 27.5 4.5 88 8 0.88 2 to 3 hours. . . 30.5 4.0 28.5 5.5 96 16 .78 3 to 4 hours. . . 27.0 0.5 20.5 -2.5 80 0 .96 4 to 5 hours. . . 27.5 1.0 25.0 2.0 86 6 .80 5 to 6 hours. . . 27.0 0.5 24.0 1.0 82 2 .81 Total . . . 145.5 13.0 125.5 10.5 432 32 'Amount does not cover the duration of the experiment by 1 \ hours ; sample included amount for about 2 hours preceding the first period. 2Heat eliminated corrected for change in body-weight, but not for change in body-temperature. ing to about 13 grams of carbohydrate. This amount probably had but little, if any, effect upon the carbon-dioxide production. The food contained 9.55 grams of nitrogen. The results of the experiment are given in table 209. Apparently the ingestion of the beefsteak and bread produced a marked effect upon the metabolism of the subject, as the increase continued throughout the 5-hour experiment, although the nitrogen excretion per hour was not so great as in the experiment on January 12. (See table 208.) It is unfortunate that a basal value for this experiment could not have been determined on the same day, TABLE 209.— F. M. M., January 14, 1910. Sitting. (1-hour periods.) Beefsteak and bread: Amounts, 201 grams beefsteak, 24 grams bread; nitrogen, 9.55 grams; total energy, 483 cals. Fuel value: Total, 399 cals.; from protein, 61 p. ct.; from fat, 26 p. ct.; from carbohydrates, 13 p. ct. Basal values (January 31 to February 19, 1910) : CC>2, 26.5 grams; 62, 23 grams; heat,1 80 cals. Time elapsed since subject finished eating. Nitrogen in urine per hour. Carbon dioxide. Oxygen. Heat.1 Respira- tory quotient. Total. Increase. Total. Increase. Total. Increase. gram . grams. grams. grams. grams. cals. cals. 1J to 2J hours 0.74 32.5 6.0 25.0 2.0 92 12 0.94 2i to 3i hours .74 32.5 6.0 29.0 6.0 93 13 .82 31 to 4i hours .74 30.5 4.0 26.5 3.5 92 12 .84 4J to 51 hours .74 29.0 2.5 24.0 1.0 85 5 .88 5 5 to 6i hours .78 29.5 3.0 29.5 6.5 84 4 .73 Total .... 154.0 21.5 134.0 19.0 446 46 'Heat eliminated corrected for change in body-weight, but, not for change in body-temperature. 278 FOOD INGESTION AND ENERGY TRANSFORMATIONS. for the total increments computed from the basal values and the values measured after the ingestion of the food are much larger than in the two preceding experiments with the same subject and with essentially the same protein intake. The chief value of the results of this experi- ment lies in the fact that they show the highest effect to be found in the first few hours after the ingestion of food. BEEFSTEAK AND POTATO CHIPS. As it was somewhat difficult for the subjects to eat beefsteak alone, approximately 20 grams of potato chips were taken in a few of the Boston calorimeter experiments. The potato chips contained a con- siderable proportion of fat and about the same amount of carbohy- drate.1 The carbohydrate thus added to the diet was not sufficient to affect the measurements appreciably and, in view of the relatively large amount of fat in the beefsteak, it was assumed that the addi- tional fat in the potato chips would play but a small part in the total metabolism. The five experiments in this series were made between January 17 and May 11, 1911, the amount of beefsteak ranging from 193 to 272 grams. These experiments continued for 3 hours after the food was ingested. Thus the total time for the preceding basal ex- periment and the food experiment was about 8 hours, which was as long as it was practicable for the subjects to remain quiet. In all cases the measurements were made in periods of 45 minutes. It was subsequently decided that observations of this length with the calorimeter did not give results with a sufficient degree of accuracy and their use was discontinued in later experimenting. Except in the experiment with J. J. C. on May 11, 1911, the basal values for this series of observations were determined on the same day as the meta- bolism subsequent to the ingestion of the beefsteak and potato chips. Truly comparable values were thus obtained. Statistical data not included in the tables or in the discussion of the experiments are here given: J. J. C., 9h%4m a. m. to Sh37m p. m., January 17, 1911. 64.9 kilograms. 3 basal periods. — Low-carbohydrate supper preceding day. Basal periods ended Ilh42m a. m.; food periods began 12h37m p. m. Went to sleep at begin- ning of first basal period, but was wakened 20 minutes after period had begun; very quiet all of this period, reading when awake. Quiet for most part in second basal period, dozing slightly once. Very quiet in last basal period, also in first, second, and third food periods, and slept part of time in third food period. More wide-awake in last food period than previously and very quiet, especially at end. Urinated 7 a. m., Ilh04m a. m., and 3h50m p. m. ; went through motions of urinating each period, usually near beginning of period. Basal periods: pulse rate, 62; respiration rate, 17. Food periods: pulse rate, 64; respiration rate, 17. J. J. C., 12*lom p. m. to 6hlom p. m., May 11, 1911. 64.6 kilograms. — Very quiet throughout experiment, sleeping greater part of time. Moved consider- p. 258 and table 50. INGESTION OF PROTEIN DIETS. 279 ably near beginning of both second and sixth periods, answering telephone in latter period and adjusting stethoscope. Urinated 8 a. m., 10h50m a. m., and 6h23m p. m. Body-temperature: 37.12°, 37.11°, 37.00°, 36.94°, 36.88°, 36.71°, 36.59°, 36.43°, 36.47° C. Pulse rate, 59. C. H. H., 8ho8m a. m. to 2h18m p. m., January 18, 1911. 54.8 kilograms. 2 basal periods. — Basal periods ended at 10h28m a. m. ; food periods began at Ilh18m a. m. Urinated and defecated at 6h30m a. m. and urinated at 2h47m p.m. Quiet throughout experiment. Basal periods: pulse rate, 68; respira- tion rate, 16. Food periods: pulse rate, 74; respiration rate, 18. V. G., 8*55m a. m. to 2h4-5m p. m., January 21, 1911. 55.3 kilograms. 2 basal periods. — Low carbohydrate supper previous day. Basal periods ended at 10h25m a. m. ; food periods began at 1 Ih43m a. m. Drank 154 c.c. water with food. Urinated 7h48m a. m., 10h35m a. m., 3 p. m. ; went through motions of urinating near beginning of each period. Basal periods: pulse rate, 67; respiration rate, 21. Food periods: pulse rate, 66; respiration rate, 21. A.G.E., 8h47m a. m. to 2*52™ p. m., January 23, 1911. 56.4 kilograms. 2 basal periods. — Basal periods ended 10h17m a. m. ; food periods began Ilh52m a. m. Drank 125 c.c. water with food. Very quiet throughout whole experi- ment; urinated 7 a. m., 10h28m a. m., 3 p. m. Basal periods : pulse rate, 70; respiration rate, 15. Food periods: pulse rate, 72; respiration rate, 15. Discrssiox OF EXPERIMENTS. /. /. C., January 17, 1911. — The results of the experiment are given in table 210, from which it is seen that the increment in metabolism continued throughout the four periods. The inference from the values obtained would be that the effect of the food was still persisting at the end of the experiment. This appears the more probable, for we have here no uncertain basal value, as the post-absorptive metabolism values were also determined on this day. It is clear, therefore, that with this TABLE 210. — J. J. C., January 17, 1911. Sitting. (45-minute periods.) Beefsteak and potato chips: Amounts, 193 grams beefsteak, 20 grams potato chips; nitrogen, 8.99 grams; total energy, 504 cals. Fuel value: Total, 425 cals.; from protein, 54 p. ct. ; from fat, 39 p. ct. ; from carbohydrates, 7 p. ct. Nitrogen in urine, 0.44 gram per 45 minutes.1 Basal values (January 17, 1911): CC>2, 19.5 grams; O%, 18 grams; heat (computed), 60 cals.; respiratory quotient, 0.78. Nitrogen in urine, 0.32 gram per 45 minutes. Time elapsed Carbon dioxide. Oxygen. Heat (computed). since subject Respiratory finished quotient. eating. Total. Increase. Total. Increase. Total. Increase. grams. grams. grams. grams. cals. cals. i to 1J hours 22.0 2.5 19.5 1.5 66 6 0.82 Iito2 hours 21.5 2.0 19.5 1.5 65 5 .81 2 to 2} hours 21.5 2.0 21.5 3.5 70 10 .74 2J to 3i hours 22.5 3.0 20.0 2.0 67 7 .83 Total . . . 87.5 9.5 80.5 8.5 268 28 'Sample included amount for about 1 hour preceding eating of food. 280 FOOD INGESTION AND ENERGY TRANSFORMATIONS. subject the ea.ting of 193 grams of beefsteak with a nitrogen content of 8.99 grams and 20 grams of potato chips, resulted in an increased metabolism which persisted at a noticeable level for the 3 hours of the experiment. J. J. C., May 11, 1911. — This is one of the few experiments in this research in which the bed calorimeter was used instead of the chair calorimeter. In the bed calorimeter there is usually a somewhat greater degree of muscular repose, as the subject is lying down instead of sitting up in a chair. The post-absorptive metabolism for J. J. C. was not determined on the same day with the bed calorimeter; it was therefore necessary to utilize post-absorptive values obtained with the apparatus in experiments made between October 27 and November 15, 1910, approximately 6 months prior to the experiment with beef- steak and potato chips. In the experiment with this subject on Janu- ary 17, it appeared that the full effect of the food was not determined during the period of the observations; the experiment on May 11 was therefore continued for eight 45-minute periods instead of for four periods, as in the other experiments of the series. The results of the experiment are given in table 211. TABLE 211. — J. J. C., May 11, 1911. Lying. (45-minute periods.) Beefsteak and potato chips: Amounts, 270 grams beefsteak, 41 grams potato chips; nitrogen, 12.67 grams; total energy, 787 cals. Fuel value: Total, 676 cals.; from protein, 48 p. ct. ; from fat, 41 p. ct. ; from carbohydrates, 11 p. ct, Nitrogen in \irine, 0.51 gram per 45 minutes.1 Basal values (October 27 to November 15, 1910): CO2, 17 grams; C>2, 14 grams; heat,2 49 cals. Time elapsed Carbon dioxide. Oxygen. Heat.2 since subject Respiratory fmished quotient. eating. Total. Increase. Total. Increase. Total. Increase. grams. (jrams. grams. grams. cals. cals. 4 to 42 hours 21.5 4.5 17.0 3.0 56 7 0.93 4J to 5i hours 19.5 2.5 18.0 4.0 61 12 .78 5 i to 6J hours 19.0 2.0 16.0 2.0 55 6 .87 6i to 7 hours 18.5 1.5 16.0 2.0 61 12 .85 7 to 7 j hours 17.0 0.0 15.5 1.5 67 8 .80 7J to 8i hours 17.5 0.5 16.5 2.5 56 7 .77 8i to 9} hours 17.0 0.0 14.0 0.0 43 -6 .89 9 J to 10 hours 17.0 0.0 16.5 2.5 46 -3 .75 Total . . . 147.0 11.0 129.5 17.5 435 43 .... 'Nitrogen in an earlier sample for 2J hours following the eating of the food was 0.50 gram per 45 minutes. 'Heat eliminated corrected for change in body-weight, but not for change in body-temperature. Following the ingestion of 270 grams of beefsteak, with a nitrogen content of 12.67 grams, and 41 grams of potato chips, the increment in carbon-dioxide production continued for only four periods. The INGESTION OF PROTEIN DIETS. 281 increment in oxygen consumption was irregular after the first four periods and reached a basal value in the seventh period, but again increased in the last period. The increment in heat production was found in all of the periods but the last two, when values slightly below the basal were obtained. C. H. H., January 18, 1911.— The results of the experiment are given in table 212. As a result of the ingestion of 213 grams of beefsteak with a nitrogen content of 9.91 grams, and 20 grams of potato chips, the carbon-dioxide production showed a slight increment in all of the periods; the only notable increase was that in the third period. As the basal value was obtained on the same day, the slight gains can not be attributed to inaccuracy of the base-line. Both oxygen consumption and heat production showed a similar general picture of small incre- ments, with the maximum in the third period. As the basal values had not been reached at the end of the experiment, it is probable that the influence of the ingestion of food was still in effect. TABLE 212. — C. H. H., January 18, 1911. Sitting. (45-minute periods.) Beefsteak and potato chips: Amounts, 213 grams beefsteak, 20 grams potato chips; nitrogen, 9.91 grams; total energy, 547 cals. Fuel value: Total, 460 cals.; from protein, 55 p. ct. ; from fat, 36 p. ct. ; from carbohydrates, 9 p. ct. Nitrogen in urine, 0.25 gram per 45 minutes.1 Basal values (January 18, 1911): CO*, 16.5 grams; Oj, 15 grams; heat,2 45 cals.; respiratory quotient, 0.81. Time elapsed Carbon dioxide. Oxygen. Heat.2 since subject Respiratory finished quotient. eating. Total. Increase. Total. Increase. Total. Increase. grams. grams. grams. grams. cals. cals. i to 1J hours 17.0 0.5 16.0 1.0 48 3 0.77 1 i to 2 hours 17.5 1.0 15.5 0.5 49 4 .81 2 to 2J hours 19.0 2.5 17.5 2.5 50 5 .78 2f to 3i hours 17.5 1.0 16.0 1.0 48 3 .78 Total . . . 71.0 5.0 65.0 5.0 195 15 'Sample included amount for 4 hours without food preceding the eating of beefsteak and potato chips. "Heat eliminated corrected for change in body-weight, but not for change in body-temperature. V. G., January 21, 1911. — The amount of food taken by this subject was 215 grams of beefsteak, with a nitrogen content of 10 grams, and 20 grams of potato chips. The data given in table 213 show incre- ments in carbon-dioxide production for the first three periods, and for oxygen consumption in the first two periods, with a basal value for the latter in the third period and an increase above basal in the fourth period. An increment in heat production was obtained in all of the periods, but that for the third period was slight. If the values for oxv- 282 FOOD INGESTION AND ENERGY TRANSFORMATIONS. gen consumption and heat production in the third period are correct, the metabolism had returned to the basal level in that period and the figures obtained for the fourth period were therefore abnormal and due to some extraneous factor. On the other hand, an examination of the respiratory quotients shows an abnormally high value of 0.89 in the third period, which suggests an error in the measurement of oxygen consumption with a possible compensation in the fourth period. An TABLE 213. — V. G., January 21, 1911. Sitting. (45-minute periods.) Beefsteak and potato chips: Amounts, 215 grams beefsteak, 20 grams potato chips; nitrogen, 10 grams; total energy, 551 cals. Fuel value: Total, 463 cals.; from protein, 55 p. ct. ; from fat, 36 p. ct.; from carbohydrates, 9 p. ct. Nitrogen in urine, 0.32 gram per 45 minutes. Basal values: COz, 22 grams (January 21, 1911); 62, 19 grams (January 2 and 21, 1911); heat (computed), 64 cals. (January 21, 1911). Nitrogen in urine, 0.20 gram per 45 minutes. (January 21, 1911). Time elapsed Carbon dioxide. Oxygen. Heat (computed). since subject Respiratory finished quotient. eating. Total. Increase. Total. Increase. Total. Increase. grams. grams. grams. grams. cals. cals. 1 to 1J hours 22.5 0.5 20.5 1.5 68 4 0.79 1J to 2J hours 23.5 1.5 23.0 4.0 75 11 .76 2 i to 3J hours 23.0 1.0 19.0 0.0 65 1 .89 3} to 4 hours 22.0 0.0 21.0 2.0 69 5 .77 Total . . . 91.0 3.0 83.5 7.5 277 21 TABLE 214. — A. G. E., January 23, 1911. Sitting. (45-minute periods.) Beefsteak and potato chips: Amounts, 272 grams beefsteak, 20 grams potato chips; nitrogen, 12.63 grams; total energy, 677 cala. Fuel value: Total, 566 cals.; from protein, 57 p. ct. ; from fat, 37 p. ct. ; from carbohydrates, 6 p. ct. Nitrogen in urine, 0.42 gram per 45 minutes. Basal values (January 23, 1911): CO2, 18 grams; Oa, 16 grams; heat,1 53 cals.; respiratory quotient, 0.82. Nitrogen in urine, 0.21 gram per 45 minutes. Time elapsed Carbon dioxide. Oxygen. Heat.1 since subject Respiratory finished quotient. eating.2 Total. Increase. Total. Increase. Total. Increase. grams. grams. grama. grams. cals. cals. J to 1 J hours 19.5 1.5 18.5 2.5 55 2 0.77 1J to 2J hours 20.5 2.5 17.5 1.5 56 3 .84 2 1 to 3 hours 21.5 3.5 20.0 4.0 58 5 .78 3 to 31 hours 20.5 2.5 17.5 1.5 55 2 .86 Total. . . 82.0 10.0 73.5 9.5 224 12 1Heat eliminated corrected for change in body-weight, but not for change in body- temperature. 'Subject ate food in 28 minutes. INGESTION OF PROTEIN DIETS. 283 examination of the protocols of the experiment indicates that there was somewhat more repose when the basal values were obtained than during the measurement after the food was taken. The increments here noted would therefore be larger than would be expected if the degree of repose were the same in both experiments. A. G. E., January 23, 1911. — After the ingestion of 272 grams of beefsteak with a nitrogen content of 12.63 grams, and 20 grams of potato chips, measurable increases were obtained for all of the factors of metabolism. (See table 214.) Although there is a lessening incre- ment in the last period, the indications are that the stimulus to the metabolism had not ceased at the end of the experiment. The maxi- mum values in all cases occur in the third period. RESPIRATION EXPERIMENTS WITH BEEFSTEAK. The series of respiration experiments with beefsteak included 14 experiments with 10 subjects made between November 3, 1910, and December 12, 1914. The routine in these experiments was not unlike that followed in similar experiments in this laboratory, the basal value being determined on the same day prior to the ingestion of food. After the food was eaten, measurements of the metabolism were usually begun immediately and continued at intervals in periods of approxi- mately 15 minutes for a varying length of time. In one instance, the experiment with H. L. H., on July 1, 1911, the observations continued for 12 hours after the food was given, but in the majority of cases they ended inside of 3 to 6 hours. Throughout the whole experiment the subject lay quietly upon a couch and every effort was made to maintain constant muscular repose. The urine was usually obtained for both the basal and food periods. All available data regarding nitrogen excretion in these experiments are given in table 216. In most of the experiments the diet consisted of beefsteak alone, but in two instances small amounts of other food materials were added. It was assumed that these small amounts had practically no influence upon the metab- olism. The pronounced effect upon metabolism occasioned by the ingestion of even moderate amounts of a protein food material has been so clearly shown, not only in all of the experiments cited in the literature but like- wise in our calorimeter experiments with beefsteak, that the results of these respiration experiments may be treated differently from those of the carbohydrate respiration experiments. The average respiratory quotient of normal man in the post-absorptive condition is not far from 0.83. Since this is approximately the respiratory quotient of protein katabolism, the respiratory quotients in our experiments with a protein diet do not have the special interest that they have in the carbohydrate experiments. Consequently it seems unnecessary to publish the de- 284 FOOD INGESTION AND ENERGY TRANSFORMATIONS. tails of these experiments, as our main interest lies in the influence of the ingestion of protein upon the heat production as computed from the values for oxygen consumption and carbon-dioxide production. We shall therefore confine our discussion chiefly to the changes in the energy output as the observations continued. The results of the respiration experiments with beefsteak have been summarized on this basis in table 215, which gives the amount of steak eaten, the basal heat production expressed in calories per minute, and the heat pro- duction in calories per minute for successive periods. The data are arranged according to the amount of beefsteak eaten, the largest amount being 362 grams and the smallest 150 grams. The data for the nitrogen excreted, so far as available, are given in table 216. TABLE 215. — Heat produced (computed) in respiration experiments with beefsteak. (Values per minute.) Subject and date. J, o> .: aj Q ""I •sj • 03 •2 * a -^ am c C a> -o M C 2-2 -*^ £ 0 "rt *c8 % pq After the ingestion of beefsteak. Increase dur- ing period of observation.1 o N » O.S ^ a o 0 ^ X 51 0 B (N 0 50 A 0 C S'§ •* Hl« *-< 03 E 0 3 += 0 r-t (M , 93 O >- •*> p rtIM ^ 1~4 1|C« M M 2g «•« co si s* ^ o B °§ CO* iO m sg «•" CD 03 *§ •»•" t~ o§ ^ § 0* Total. Per cent. J. J. C... .Apr. 25, 1911 H. L. H.. . May 20, 1914 July 1, 1911 H. G. E. .Dec. 12, 1914 J. F. M.. .Apr. 23, 1914 J. K. M. .Nov. 26, 1912 D. M Oct. 28, 1911 am. 3622 317 249 200 198 196 182 177 173 1694 150 150 150 150 gm. 17.73 14.56 11.44 9.18 9.09 9.01 8.35 8.13 7.95 8.59 7.74 6.92 8.00 7.07 col. 1.11 1.14 1.11 1.24 1.24 1.08 1.09 0.93 1.25 1.10 1.10 1.12 1.17 1.11 cal. cal. cal. 1 25 cal. 1 30 cal. cal. 1 41 cal. 1 47 cal. 1 49 cal. 1 37 cal. 1 34 cal. cal. 81 13 138 25 19 28 86 56 17 23 10 18 12 11 14 25 15 8 19 6 13 13 1 28 1 29 1 29 1.17 1 18 1.28 1.34 1 45 1.38 1.44 1.28 1.303 1 38 1 38 1.45 1.18 1 34 1 3? 1 41 1 42 1.14 1 26 1.17 1.21 1 34 1.23 1 35 1.29 1 47 1.33 1 58 1 30 1 26 Dr. S June 30, 1911 1.05 1 08 1.11 1 40 1.13 1 40 1.13 1.05 1.03 1.00 A. J. O. ..Nov. 17, 1914 H. H. A. .Dec. 27, 1911 J. J. C... .Nov. 3, 1910 Nov. 8, 1910 V. G Nov. 4, 1910 1 30 1 31 1 33 1 43 1 35 1 36 1 16 1 24 1 32 1 37 1 40 1 34 1 37 51 13 24 38 1.10 1.14 1 15 1.26 1 34 1.26 1 35 1.38 1 37 Nov. 7, 1910 1.19 1 21 1.30 1.28 1.33 1Time from the moment subject finished eating to the end of the last experimental period; see pp. 151 and 152 for method of obtaining total increase. 2Also 15 grams potato chips. Nitrogen in food includes the nitrogen in both beefsteak and potato chips. 'Additional values were obtained for 7 to 8, 8 to 9, 9 to 10, 10 to 11, 11 to 12 hours as follows: 1.39, 1.32, 1.29, 1.21, and 1.31 cals. 4Also 15 grams butter and 200 grams beef tea. Nitrogen in food includes nitrogen for all of the food eaten. In computing the calories per minute the respiratory quotients as determined were used and not the non-protein respiratory quotients. A calculation of a few of these experiments showed practically no important changes due to a use of the non-protein quotient;1 accord- ingly we may disregard the calculation and employment of the non- protein respiratory quotient and consider that the calorie output recorded in table 215 represents the heat production. 1See p. 203 for comparison made in typical experiments with levulose; similar comparisons made in experiments with beefsteak showed like small differences in the heat production. INGESTION OF PROTEIN DIETS. 285 TABLE 216. — Nitrogen excreted in urine in respiration experiments with beefsteak. Subject and date. Condition. Period. Finished eating. Nitrogen per hour. J. J. C Apr. 25 1911 Without food. 7b41ma.m. to 10h15ma.m. grams. 0 33 H. L. H..July 1, 1911.. With food Without food.. 10 15 a.m. to 4h30mp.m. 7 10 a.m. to 10 55 a.m. 10h31ma.m. .64 .58 With food .... Do 10 55 a.m. to 4 55 p.m. 4 55 p.m. toll 05 p.m. 11 15 a.m. .86 .69 H. G. E..Dec. 12, 1914. Without food. . 7 15 a.m. to 10 00 a.m. .32 WTith food .... Do 10 00 a.m. toll 30 a.m. 11 30 a.m. to 1 15 p.m. 10 15 a.m. .49 56 J. K. M..NOV. 26, 1912.. 6 20 a.m. to 12 55 p.m. 11 10 a.m. .51 D. M. . . Oct. 28, 1911 Without food. 6 40 a.m. to 9 20 a.m. 58 Do 9 20 a.m. to 11 50 a.m. .52 Dr. S. . . .June 30, 1911.. With food Without food. . 11 50 a.m. to 8 05 p.m. 7 15 a.m. to 10 40 a.m. 2 48 p.m. .67 .33 With food .... Do 10 40 a.m. to 1 30 p.m. 1 30 p.m. to 5 03 p.m. 11 15 a.m. .45 .62 A. J. O.-.Nov. 17, 1914 Without food. 7 50 a m. to 9 55 a.m. 69 With food. . . . Do 9 55 a.m. to 11 20 a.m. 11 20 a.m. to 12 45 p.m. 9 53 a.m. .94 1.08 J. J. C. . .Nov. 3, 1910 . Without food. . 8 00 a.m. to 1 30 p.m. .37 Nov. 8, 1910. With food Without food. . 1 30 p.m. to 6 00 p.m. 7 10 a.m. to 2 05 p.m. 1 40 p.m. .57 .32 V. G Nov. 4, 1910.. With food .... Without food. 2 05 p.m. to 5 45 p.m. 7 42 a.m. to 2 55 p.m. 2 28 p.m. .38 .32 Nov. 7, 1910. . With food Without food. . 2 55 p.m. to 6 05 p.m. 7 30 a.m. toll 18 a.m. 3 20 p.m. .39 .27 Do 11 18 a.m. to 1 05 p.m. .20 With food 1 05 p.m. to 5 40 p.m. 1 05 p.m. .30 The pronounced increase over the basal metabolism is instantly noted in practically all experiments. As might be expected, the higher values are usually obtained with the larger amounts of steak. For instance, in the experiment with J. J. C. on April 25, 1911, when 362 grams of beefsteak were eaten, the basal value of 1.11 calories was increased to 1.49 calories between 3 and 4 hours after the food. As a matter of fact, the highest absolute increment was noted with only 182 grams of beefsteak, this being in the experiment with D. M. on October 28, 1911, when the basal value of 1.09 calories was increased in 3 hours to 1.58 calories, or approximately 45 per cent. Of special significance is the fact that the basal value was not reached in any of these experiments, even when the observations were continued for 12 hours. It should again be pointed out that these results are open to the ob- jection that, unlike Gigon's admirably planned experiments, the food material used was not a pure protein, but that there was a certain admix- ture of fat, even though all visible fat was removed. The data obtained in these respiration experiments show clearly, however, that the inges- tion of beefsteak in amounts varying from 150 to 362 grams results in a sustained increase in metabolism which is for the most part 286 FOOD INGESTION AND ENERGY TRANSFORMATIONS. greater than that noted either with carbohydrate food materials or with fats. This effect in practically all instances continues over a much longer tune than with either of the other nutrients, thus putting this protein food material in a distinctly special class so far as the influence upon the metabolism is concerned. PROLONGED EFFECT OF PROTEIN. Two respiration experiments were carried out in July, 1911, to study the metabolism several hours after the ingestion of beefsteak. In both instances the steak was eaten at midnight and the subsequent experi- ments began at approximately 8h30m a. m. In the experiment with H. F. T., July 14, 1911, the subject ate 206 grams of beefsteak, with a nitrogen content of 9.46 grams; the first observation was made at 8h36m a. m. The heat production for this period, as shown by table 217, was 0.92 calorie per minute. The two succeeding periods did not show materially different results. If we compare the heat production in this experiment with the basal value of 0.92 calorie per minute found for this subject on July 10, 1911, it is clear that the effect of 206 grams of beefsteak had entirely passed at the end of 8| hours. The nitrogen excretion for approximately 11 hours after the ingestion of the food was as follows: Between Ilh45m p. m., July 13, and 7 a. m., July 14, 0.80 gram per hour; between 7 a. m. and 10h40m a. m., July 14, 0.69 gram per hour. TABLE 217.— H. F. T., July 14, 1911. Lying. (Values per minute.) Beefsteak: Amount, 206 grams; nitrogen, 9.46 grams; total energy, 428 cals. Fuel value: 346 cals.; from protein, 70 p. ct. ; from fat, 30 p. ct. Time. Average respiration rate. Carbon dioxide. Respira- tory quotient. Oxygen. Average pulse rate. Heat (com- puted) . c.c. c.c. cals. SKse^a.m.1 . . 10 156 0.81 192 44 0.92 9 07 a.m. . . 10 141 .76 186 44 .88 9 48 a.m. . . 11 155 .82 188 45 .91 beefsteak eaten at 12 midnight July 13. A similar experiment was made with the subject H. L. H., on July 15, 1911, in which 249 grams of beefsteak, with a nitrogen content of 11.44 grams, were eaten at midnight; beginning at 8h59m a. m. the next day, the metabolism was observed approximately every hour, the last observation being at 3h16m p. m. The results of the experi- ment are given in table 218. The calories per minute varied from 1.15 to 1.31, the highest value being found in the last period. Com- paring these results with the basal heat production of 1.11 calories INGESTION OF PROTEIN DIETS. 287 found for this subject approximately two weeks previous, we note that the basal value was exceeded in all of the observations on July 15. This is in full conformity with the experiment of July 1, 1911, given in table 215, which showed that with this subject exactly the same amount of beefsteak had a prolonged effect which continued 12 hours or more. TABLE 218. — H. L. H., July 15, 1911. Lying. (Values per minute.) Beefsteak: Amount, 249 grams; nitrogen, 11.44 grams; total energy, 518 cals. Fuel value: Total, 418 cals.; from protein, 70 p. ct. ; from fat, 30 p. ct. Time. Average respiration rate. Carbon dioxide. Respira- tory quotient. Oxygen. Average pulse rate. Heat (com- puted) . c.c. c.c. cals. S^^a.m.1. 16 190 0.75 255 60 1.21 9 41 a.m. . 15 187 .76 247 60 1.17 10 25 a.m . . 16 185 .76 243 58 1.15 11 08 a.m. . 15 191 .76 250 59 1.19 12 11 p.m. . 15 203 .76 266 64 1.26 12 58 p.m. . 197 .78 253 62 1.21 2 12 p.m. . 208 .78 268 65 1.28 3 16 p.m.. 15 207 .75 277 67 1.31 beefsteak eaten between 12h03m and 12h10m a. m. The nitrogen excretion for 14| hours after the ingestion of the beef- steak was as follows: Between 10h30m p. m., July 14, to 7h40m a. m., July 15, 0.67 gram per hour; between 7h40m a. m. and 2h40m p. m., July 15, 0.71 gram per hour. It is clear that these two experiments are not at all in agreement so far as the two subjects are concerned, and yet more nearly comparable experiments with H. L. H. than those of July 1 and July 15 can hardly be expected. With this subject, at least, 249 grams of beefsteak resulted in a stimulus to the meta- bolism which persisted 8 to 12 hours and probably somewhat longer. A similar experiment was made with Dr. S.1 on July 13, 1911 (details not here given), in which but 73 grams of beefsteak, with a nitrogen con- tent of 3.36 grams, were eaten at midnight. The average heat produc- tion for three experimental periods the next morning between 9 and 10 o'clock was 0.92 calorie. This is the basal value for this subject; hence the only deduction that can be drawn is that the small amount of beef- steak was without influence upon the basal metabolism 9 hours after eating. CONCLUSIONS AS TO THE EFFECT OF INGESTING BEEFSTEAK. A study of the results obtained from all of the experiments in which beefsteak was ingested leads us to the conclusion that 200 grams of cooked steak, containing 8 to 10 grams of nitrogen, produce a rise in desire to acknowledge the hearty cooperation of our colleague, Professor H. Monmouth Smith, who was a voluntary observer at the time these experiments were made. 288 FOOD INGESTION AND ENERGY TRANSFORMATIONS. the heat output of from 8 to 12 calories per hour for 6 to 12 hours, and that the total effect upon the heat output is not complete in 12 hours. The period of maximum rise in metabolism probably occurs within the first 4 hours, although a considerable increase may be found for a much longer period.1 GLIDINE. In May 1910, five experiments were made with a vegetable protein substance called "glidine,"2 which is claimed to be the gliadin of wheat. As will be seen from table 50 (page 124), this food material had a protein content of approximately 87 per cent. An unfortunate feature of the experiments with glidine was the fact that the subjects found it almost impossible to eat any considerable amount. The largest amount taken was 70 grams, which was used in two experiments; in three experiments the subject took only 45 grams. All the observations were made with the chair calorimeter. The statistical data not included n the tables or the discussion of the experiments are given here : L. E. E., 8h40m a. m. to 3h19m p. m., May 3, 1910. 59.6 kilograms. 2 basal periods. — Basal periods ended 10h40m a. m.; food periods began Ilh19m a. m. Subject unable to take a large amount of glidine without nausea. Urinated 6h30ra, 8H7m, 10h45m a. m., 12h19m, 2h19m, 3h19m p. m. Drank 85 grams water 12h19m p. m. Asleep 12h04ra p. m. to 12h12m p. m. and Ih32m p. m. to 2h08m p. m.; restless at other times. Rectal thermometer slipped out of position in third food period; temperature records not available after 12h19m p. m. Basal periods: body-temperature, 36.90°, 36.81°, 36.93° C.; pulse rate, 56; respiration rate, 16. Food periods: body-temperature, 36.92°, 36.94° C.; pulse rate, 55; respiration rate, 17. L. E. E., 8h31m a. m. to 2h13™ p. m., May 11, 1910. 59.2 kilograms. 2 basal periods. — Fasting periods ended at 10h31m a. m.; food periods began at Ilh13m a. m. Subject defecated and urinated at 6h45m a. m.; urinated at 10h31m a. m. and 2h15m p. m. In first part of first basal period, there was a decided movement and subject was cautioned to keep quiet. Asleep at end of period; awakened at beginning of next period. Rectal thermometer not used after Ih17m p. m. Basal periods: pulse rate, 56; respiration rate, 17. Food periods: pulse rate, 57; respiration rate, 18. J. J. C., 9h31m a. m. to 4h43m p. m., May 9, 1910. 64.5 kilograms. 2 basal periods. — Basal periods ended Ilh31m a. m.; food periods began 12h43m p. m. Subject urinated 6h45m, Ilh36m a. m., 3h53m, 4h55m p. m. Asleep Ilh10m a. m., Ih28m p. m., Ih48m p. m. and was awakened. Basal periods: body-tempera- ture, 36.6°, 36.69°, 36.7° C. ; pulse rate, 60 ; respiration rate, 19. Food periods : body-temperature, 36.79°, 36.78°, 36.80°, 36.77°, 36.85° C.; pulse rate, 59; respiration rate, 19. J. R., 8*38m a. m. to 3h22m p. m., May 5, 1910. 70.1 kilograms. 2 basal periods. — Basal periods ended 10h38ra a. m.; food periods began Ilh22m a. m. Urinated 7 a. m., 10h40m a. m., 3h30m p. m. Very sleepy during greater part 'It is of interest to note here that Aub and DuBois, in a recent research, found larger increases in the metabolism following the ingestion of beefsteak with abnormal individuals (a dwarf and a legless man) than with normal individuals of greater weight and body-surface area. (Aub and DuBois, Arch. Intern. Med., 1917, 19, p. 840.) 'Street, Ann. Rept. Conn. Agr. Exp. Sta., 1913. INGESTION OF PROTEIN DIETS. 289 of afternoon and asleep just before 2h22m p. m. but awoke shortly afterwards. Basal periods: body-temperature, 37.01°, 37.01°, 37.09° C.; pulse rate, 65; respiration rate, 15. Food periods: body-temperature, 37.22°, 37.14°, 37.28°, 37.19°, 37.37° C.; pulse rate, 68; respiration rate, 15. J. R., 8h37m a. m. to 3h12m p. m., May 10, 1910. 71.0 kilograms. 2 basal periods. — Basal periods ended 10h37rn a. m.; food periods began Ilh12m a. m. Subject felt chilly at first. Urinated 7 a. m., 10h37m a. m. and 2h16m p. m. Basal periods: body-temperature, 37.00°, 36.90°, 37.08° C.; pulse rate, 66; respiration rate, 16. Food periods: body-temperature, 37.23°, 37.56°, 37.47°, 37.38°, 37.46° C.; pulse rate, 75; respiration rate, 16. DISCUSSION OF EXPERIMENTS. L. E. E., May 3, 1910.— The subject took 45 grams of glidine sus- pended in 110 grams of water, with a nitrogen content of 6.24 grams; the results obtained are given in table 219. The basal value was found on the same day, immediately prior to the ingestion of the glidine. A marked increment in carbon-dioxide production and oxygen consump- tion was noted in all the periods of the experiment and an increase in heat production in the first two periods; in the last two periods the values for the heat production were within 1 calorie of the basal value. TABLE 219.— L. E. E., May 3, 1910. Sitting. (1-hour periods.) Glidine:1 Amount, 45 grams; nitrogen, 6.24 grams; total energy, 223 cals. Fuel value: Total, 168 cals.; from protein, 95 p. ct. ; from fat, 2 p. ct. ; from carbohydrates, 3 p. ct. Basal values (May 3, 1910): CO2, 25 grams; O2, 21.5 grams; heat2, 78 cals.; respiratory quotient, 0.84. Nitrogen in urine, 0.51 gram per hour. Time elapsed since subject finished eating. Nitrogen in urine per hour. Carbon dioxide. Oxygen. Heat.2 Respira- tory quotient. Total. Increase. Total. Increase. Total. Increase. gram. grams. grams. grams. grams. cals. cals. J to 1$ hours 0.52 27.0 2.0 25.5 4.0 80 2 0.76 1 J to 2 J hours .70 31.5 6.5 27.5 6.0 87 9 .83 2J to 3J hours .70 27.5 2.5 26.0 4.5 79 1 .77 3J to 4$ hours .66 28.5 3.5 25.5 4.0 79 1 .81 Total .... 114.5 14.5 104.5 18.5 325 13 Subject took glidine in 110 grams of water. 2Heat eliminated corrected for change in body-weight, but not for change in body-temperature. L. E. E., May 11, 1910. — The same amount of glidine was taken as in the first experiment with this subject; the basal value was determined immediately before the observations with glidine. The results are given in table 220. Noticeable increments in the carbon-dioxide pro- duction and oxygen consumption were obtained in the three 1-hour periods, but relatively insignificant increments were found in the heat production. The absence of body-temperature measurements, with the 290 FOOD INGESTION AND ENERGY TRANSFORMATIONS. consequent impossibility of correcting for changes in body-tempera- ture, may have accounted for this discrepancy. The nitrogen excretion per hour was less than in any of the periods of the former experiment. The increment in both the carbon-dioxide production and oxygen con- sumption is too great, however, not to be taken as a positive effect of the ingestion of the glidine. TABLE 220.— L. E. E., May 11, 1910. Sitting. (1-hour periods.) Glidine:1 Amount, 45 grams; nitrogen, 6.24 grams; total energy, 223 cals. Fuel value: Total, 168 cals.; from protein, 95 p. ct. ; from fat, 2 p. ct. ; from carbohydrates, 3 p. ct. Nitrogen in urine, 0.40 gram per hour. Basal values (May 11, 1910): CO2, 24.5 grams; O^, 21.5 grams; heat,2 80 cals.; respiratory quotient, 0.83. Nitrogen in urine, 0.10 gram per hour. Time elapsed since subject finished eating. Carbon dioxide. Oxygen. Heat.2 Respira- tory quotient. Total. Increase. Total. Increase. Total. Increase. grams. grains. grams. grams. cals. cals. i to 1 i hours 28.0 3.5 26.0 4.5 85 5 0.78 li to 2J hours 29.0 4.5 25.5 4.0 81 1 .83 2J to3§ hours 29.5 5.0 26.0 4.5 79 -1 .82 Total . . . 86.5 13.0 77.5 13.0 245 5 .... 'Subject took glidine in 200 grams of water. 2Heat eliminated corrected for change in body-weight, but not for change in body-temperature. J ' . J . C., May 9, 1910. — A third experiment was made in which 45 grams of glidine were given, but with another subject. The results of this experiment are found in table 221, which shows a considerable increase in all the factors of the metabolism. Even at the end of the 4 hours there is no indication that the total increase due to the glidine had been obtained. The respiratory quotients are not far from those which would be expected during the combustion of protein, although it can be computed from the values obtained for the nitrogen excretion, which average 0.58 gram per hour, that the total calories from protein can be only about one-third of the total calories found, the remainder of the metabolism being derived from fat and carbohydrates. J. R., May 5, 1910. — A larger amount of glidine was taken by this subject than in the three experiments previously discussed, the exact amount being 70 grams, with a nitrogen content of 9.70 grams. The measurements of the metabolism are given in table 222. The oxygen consumption during the second period could not be obtained, but noticeable increments were found in the other periods and also for carbon-dioxide production and heat production in all the periods. It is evident that the effect of the ingestion of this amount of glidine INGESTION OF PROTEIN DIETS. 291 TABLE 221— J. J. C., May 9, 1910. Sitting. (1-hour periods.) Glidine:1 Amount, 45 grams; nitrogen, 6.24 grams; total energy, 223 cals. Fuel value: Total, 168 cals.; from protein, 95 p. ct.; from fat, 2 p. ct.; from carbohydrates, 3 p. ct. Basal values: CO2, 24.5 grams (May 9, 1910); O2, 21 grams (March 4 to May 31, 1910); heat (computed), 72 cals. (May 9, 1910). Nitrogen in urine, 0.26 gram per hour (May 9, 1910). Time elapsed since subject Nitrogen Carbon dioxide. Oxygen. Heat (computed) . Respira- finished eating. in urine per hour. Total. Increase. Total. Increase. Total. Increase. tory quotient. gram. grams. grams. grams. grams. cals. cala. 1 to 2 hours . . . 0.57 28.5 4.0 25.0 4.0 83 11 0.82 2 to 3 hours . . . .57 26.0 1.5 24.0 3.0 79 7 .79 3 to 4 hours . . . .57 27.5 3.0 25.0 4.0 83 11 .79 4 to 5 hours . . . .61 26.5 2.0 24.5 3.5 81 9 .78 Total .... 108.5 10.5 98.5 14.5 326 38 'Subject took glidine in 164 grams of water. was considerable. As the basal values were determined on the same day as the metabolism after glidine, there can be no uncertainty as to the validity of the increments. TABLE 222.— J. R., May 5, 1910. Sitting. (1-hour periods.) Glidine:1 Amount, 70 grams; nitrogen, 9.70 grams; total energy, 347 cals. Fuel value: Total, 262 cals.; from protein, 95 p. ct.; from fat, 2 p. ct.; from carbohydrates, 3 p. ct. Nitrogen in urine, 0.83 gram per hour. Basal values (May 5, 1910): COj, 27 grams; Oz, 23 grams; heat,2 73 cals.; respiratory quotient 0.86. Nitrogen in urine, 0.44 gram per hour. Time elapsed since subject finished eating. Carbon dioxide. Oxygen. Heat,2 Respira- tory quotient. Total. Increase. Total. Increase. Total. Increase. i to 1J hours grams. 31.5 33.0 30.0 29.5 grams. 4.5 6.0 3.0 2.5 grams. 28.0 25.0 28.5 grams. 5.0 2.0 5.5 cals. 78 96 84 85 cals. 5 23 11 12 0.82 '.'88 .76 Hto2£ hours 2} to 3| hours. . . 3J to 4J hours. . . . Total 124.0 16.0 81.5 12. 53 343 51 *Taken in 200 grams of water. 2Heat eliminated corrected for change in body-weight, but not for change in body-temperature. 'Increment of oxygen for a total of 3 hours. J. R., May 10, 1910. — The same amount of glidine was taken in this second experiment with J. R. as in that of May 5, and the results are therefore comparable. Increments in the carbon-dioxide excretion, oxygen consumption, and heat production were also found in this exper- 292 FOOD INGESTION AND ENERGY TRANSFORMATIONS. iment, with no indication of a cessation in the stimulus at the end of the experiment. (See table 223.) The 70 grams of glidine therefore had a pronounced effect, which continued 4 hours, if not longer. The nitrogen excretion was strikingly lower in this experiment, but in any event the total energy from the protein katabolized can be but a relatively small part of the total heat production, probably about one- third. TABLE 223.— J. R., May 10, 1910. Silting. (1-hour periods.) Glidine:1 Amounts, 70 grams glidine, 20 grams lemon juice; nitrogen, 9.70 grams; total energy, 352 cals. Fuel value: Total, 267 cals.; from protein, 93 p. ct.; from fat, 2 p. ct. ; from carbohydrates, 5 p. ct. Nitrogen in urine, 0.72 gram per hour (in first three periods). Basal values: CO2, 27.5 grams (May 10, 1910); O2, 22.5 grams (March 21 to May 13, 1910); heat, 72 cals. (May 10, 1910). Nitrogen in urine, 0.44 gram per hour (May 10, 1910). Time elapsed since subject finished eating. Carbon dioxide. Oxygen. Heat. Respira- tory quotient. Total. Increase. Total. Increase. Total. Increase. J to 1 i hours. grams. 30.5 33.0 33.0 33.0 grams. 3.0 5.5 5.5 5.5 grams. 26.0 28.0 28.0 27.5 grams. 3.5 5.5 5.5 5.0 cals. 76 83 85 84 cals. 4 11 13 12 0.86 .86 .85 .87 li to 2\ hours. 2J to 3j hours 3J to 4j hours. . . . Total 129.5 19.5 109.5 19.5 328 40 lTaken with lemon juice and 400 grams of water. CONCLUSIONS AS TO EFFECT OF INGESTING GLIDINE. An examination of the results obtained in this series of live experi- ments with glidine shows that it produced a marked effect upon the metabolism even when such small amounts were taken as 45 grams, with a nitrogen content of approximately 6.25 grams. The two experi- ments with J. R., in which 70 grams were taken, gave a much larger increment and a more prolonged effect than the smaller amount. A comparison of these results with glidine and those obtained with other predominatingly protein diets will be made subsequently. GLUTEN BREAD AND SKIM MILK. In some of the earliest experiments in this study a special gluten bread was used which was made in the laboratory and contained a minimum amount of carbohydrate. As much of this bread as possible was taken by the subject, skim milk being added in minimum amounts to aid in its ingestion, as the bread was very dry and somewhat un- palatable. The experiments were carried out with the Middletown respiration calorimeter in May 1906, there being in all four experi- INGESTION OF PROTEIN DIETS. 293 ments with two subjects. The observations were made in 2-hour periods. The basal values were all determined on a different day from that on which the metabolism after gluten was determined. The amount of gluten bread taken in the last experiment by the second subject, H. C. K., was considerably smaller than the amounts eaten by the subject H. R. D.; H. C. K. also found it necessary to take a greater quantity of skim milk with the bread. The proportion of nitro- gen from the skim milk was therefore increased, but the experiment is included in this section for additional information as to the metabolism after the ingestion of gluten bread. Statistical data not included in the tables or in the discussion of the experiments are given here: H. R. D., 9h01m a. m. to 5h01m p. in., May 2, 1906. 58.5 kilograms.— Urinated at 7h05m a. m. and at beginning of every period. Quiet for most part during experiment; drowsy between 9 a. m. and 10 a. m.; especially quiet about 11.30 a. m.; read about three-fourths of time. Body-temperature: 36.71°, 36.70°, 36.71°, 36.76°, 36.73° C. Pulse rate, 67; respiration rate, 19. H. R. D., 9h30m a. m. to 9*30m p. m., May 9, 1906. 58.4 kilograms.— Took enema and urinated about 7h30m a. m. and urinated at beginning of every period. Distressed by rectal thermometer owing to temporary tender- ness in lower part of rectum; removed thermometer at 10h31m a. m. and ex- changed it for another, telephoning once and opening food aperture twice for the purpose; rest of time quiet and reading through first and second periods. Sat idle from Ih30m p. m. to 2h04m p. m., slept from 2h04ra p. m. to 2h32m p. m., read from 2h34m p. m. to 9h30m p. m.; drowsy at times during day. Body- temperature: no record at beginning of experiment; subsequent records, 36.85°, 37°, 36.95°, 36.95°, 37.02°, 36.78° C. Pulse rate, 63 ; respiration rate, 19. H. R. D., 9*10m a. m. to 9h10m p. m., May 17, 1906. 59.1 kilograms.— Urinated 7h15m a. m. (after enema) and also at beginning of every period. Sat quietly reading almost whole experiment. Drank 90 grams water at Ilh10m a. m. Body-temperature: 36.64°, 36.62°, 36.71°, 36.53°, 36.59°, 36.60° C. Pulse rate, 69; respiration rate, 20. H. C. K., 9h10m a. m. to 5h10m p. m., May 7, 1906. 74.4 kilograms.— Urinated and defecated about 7h10m a. m. and urinated at beginning of every period. Food difficult to swallow. Subject very quiet throughout experi- ment; fell asleep twice in second period, but not drowsy rest of time; read during most of experiment. Body-temperature : 36.34°, 36.38°, 36.53°, 36.60°, 36.66° C. ; no record at end of experiment. Pulse rate, 50; respiration rate, 19. DISCUSSION OF EXPERIMENTS. H. R. D., May 2, 1906.— In the first experiment with this subject 100 grams of gluten bread were taken and 221 grams of skim milk. The nitrogen content of the diet was 15.43 grams, the greater part of this being contained in the gluten bread. During the 8 hours of the experiment, the results of which are given in table 224, there was a continuously increasing rise in the nitrogen excretion, also an incre- ment in all of the factors of the metabolism. The maximum carbon- dioxide production was in the third period, as was also the maximum heat production. It was necessary for experimental reasons to com- 294 FOOD INGESTION AND ENERGY TRANSFORMATIONS. bine the results obtained for the oxygen consumption in the second and third periods in which the highest increment was found. Since the measured metabolism was distinctly above the basal metabolism in the fourth period, it is evident that the influence of the ingestion of food had not ceased at the end of the experiment. TABLE 224.— #. R. D., May 2, 1906. Sitting. (2-hour periods.) Gluten bread and skim milk: Amounts, 100 grams gluten bread, 221 grams skim milk; nitrogen, 15.43 grams; total energy, 631 cals. Fuel value: Total, 496 cals.; from protein, 84 p. ct.; from fat, 2 p. ct.; from carbohydrates, 14 p. ct. Basal values (February 6 to April 20, 1906): COz, 47 grams; Oz, 42 grams; heat, 146 cals. Nitrogen in urine, 0.36 gram per 2 hours (May 2, 1906). Time elapsed since subject Nitrogen in urine Carbon dioxide. Oxygen. Heat. Respira- finished eating.1 per 2 hours. Total. Increase. Total. Increase. Total. Increase. tory quotient. grams. grams. grams. grams. grams. cals. cals. 0 to 2 hours . . . 0.79 53 6 47 5 157 11 0.81 2 to 4 hours . . . 4 to 6 hours . . . 1.29 1.65 53 59 6 12 | 95 11 /157 \164 11 18 .96 .78 6 to 8 hours . . . 1.92 52 5 48 6 157 11 .78 Total 217 29 190 22 635 51 1Subject ate food in 21 minutes. H. R. D., May 9, 1906. — The amounts of gluten bread and skim milk taken in this experiment were practically the same as those taken in the first experiment with this subject, but the total period of observa- tion was lengthened in order to obtain the final effect of the ingested food. The results are given in table 225, from which it will be seen that the basal value was reached in the fifth period, both carbon-dioxide production and heat production showing values somewhat less than basal in the sixth period. In other respects the experiment is a dupli- cate of that of May 2. The nitrogen excretion reached the maximum in the fourth period and decreased thereafter. It is of interest to note that, although the nitrogen in the sixth period was considerably above the basal value, the carbon-dioxide excretion, oxygen consumption, and heat production had already reached the basal value or had fallen slightly below in this period. H. R. D., May 17, 1906. — The third experiment with this subject was made with a considerably larger amount of gluten bread, but the amount of skim milk was also increased. The total nitrogen intake was 24.47 grams, of which 21.88 grams came from gluten bread and 2.59 grams from skim milk. This experiment was also continued for 12 hours; the results are given in table 226. The increment in all the fac- tors of the metabolism was noticeable; the base-line was not reached INGESTION OF PROTEIN DIETS. 295 TABLE 225.— H. R. D., May 9, 1906. Sitting. (2-hour periods.) Gluten bread and skim milk: Amounts, 100 grams gluten bread, 220 grama skim milk; nitrogen, 15.42 grams; total energy, 622 cals. Fuel value: Total, 487 cals.; from protein, 84 p. ct. ; from fat, 2 p. ct. ; from carbohydrates, 14 p. ct. Basal values (February 6 to April 20, 1906): CO2, 47 grams; O2, 42 grams; heat, 146 cals. Nitrogen in urine, 0.44 gram per 2 hours (May 9, 1906). Time elapsed since subject Nitrogen in urine Carbon dioxide. Oxygen. Heat. Respira- finished eating. per 2 hours. Total. Increase. Total. Increase. Total. Increase. tory quotient. grams. grams. grams. grams. grams. cals. cals. 0 to 2 hours 0.80 59 12 53 11 1741 28 0.82 2 to 4 hours 1.51 56 9 52 10 173 27 .78 4 to 6 hours 1.66 52 5 50 8 155 9 .76 6 to 8 hours 2.12 53 6 46 4 156 10 .84 8 to 10 hours 1.59 49 2 44 2 158 12 .81 10 to 12 hours 1.09 45 _2 42 0 136 -10 .78 Total 314 32 287 35 952 76 .... 'Heat eliminated not corrected for small change in body-weight or for change in body-tem- perature. TABLE 226.— H. R. D., May 17, 1906. Sitting. (2-hour periods.) Gluten bread and skim milk: Amounts, 153 grams gluten bread, 499 grams skim milk; nitrogen, 24.47 grams; total energy, 1,023 cals. Fuel value: Total, 809 cals.; from protein, 81 p. ct. ; from fat, 2 p. ct. ; from carbohydrates, 17 p. ct. Basal values (February 6 to April 20, 1906): CO2, 47 grams; O2, 42 grams; heat, 146 cals. Nitrogen in urine, 0.58 gram per 2 hours (May 17, 1906). Time elapsed since subject Nitrogen in urine Carbon dioxide. Oxygen. Heat. Respira- finished eating.1 per 2 hours. Total. Increase. Total. Increase. Total. Increase. tory quotient. grams. grams. grams. grams. grams. cals. cals. 0 to 2 hours 1.29 59 12 45 3 179 33 0.97 2 to 4 hours 1.97 61 14 50 8 176 30 .89 4 to 6 hours 2.51 63 16 54 12 165 19 .85 6 to 8 hours 2.87 60 13 49 7 174 28 .90 8 to 10 hours 2.69 53 6 45 3 163 17 .86 10 to 12 hours 2.10 52 5 49 7 2162 16 .77 Total 348 66 292 40 1,019 143 1Subject ate food in 39 minutes. 2Heat eliminated corrected for change in body-weight, but not for change in body-temperature. at the end of the experiment. The maximum in nitrogen excretion was obtained in the fourth period, but although there was a tendency for it to decrease thereafter the output was very large even in the sixth period, showing a considerable metabolism of nitrogenous material. The ingestion of 24.47 grams of nitrogen, therefore, had a pronounced 296 FOOD INGESTION AND ENERGY TRANSFORMATIONS. effect upon the metabolism, which persisted for the 12 hours of the experiment and showed no indication of ceasing at the end of that time. If we compare the results with those obtained in the preceding experiment, we find the increment in carbon-dioxide production is considerably larger in this experiment and that the increment in heat production is practically twice as large, but that the increment in oxygen consumption is not far from the same in both experiments. This indicates a disparity between the direct and indirect calorimetry, which unfortunately is only too frequent in experiments of this kind. H. C. K., May 7, 1906. — Only 66 grams of gluten bread were taken in this experiment with 706 grams of skim milk. The nitrogen content of the diet was 13.04 grams, of which 9.44 grams were contained in the gluten bread. The basal values were determined but 4 days previous to the experiment and were thus approximately correct values for use in this experiment. Relatively large increments are shown in table 227 throughout the experimental period. The nitrogen excretion increased for the first three periods, but decreased slightly in the last period. Both the nitrogen excretion and the total metabolism indicate that the effect of ingesting this protein food material was still felt at the end of the experiment. TABLE 227.— H. C. K., May 7, 1906. Sitting. (2-hour periods.) Gluten bread and skim milk: Amounts, 66 grams gluten bread, 706 grams skim milk; nitrogen, 13.04 grams; total energy, 672 cals. Fuel value: Total, 558 cals.; from protein, 65 p. ct. ; from fat, 4 p. ct. ; from carbohydrates, 31 p. ct. Basal values (May 3, 1906): CC>2, 51 grams; O2, 47 grams; heat, 164 cals. Nitrogen in urine, 1 gram per 2 hours (May 7, 1906). Time elapsed since subject Nitrogen in urine Carbon dioxide. Oxygen. Heat. Respira- finished per tory eating.1 2 hours. Total. Increase. Total. Increase. Total. Increase. quotient. grams. grams. grams. grams. grams. cals. cals. 0 to 2 hours . . . 1.22 60 9 56 9 177 13 0.78 2 to 4 hours . . . 1.63 61 10 56 9 177 13 .79 4 to 6 hours . . . 2.09 65 14 53 6 179 15 .90 6 to 8 hours . . . 1.87 57 6 56 9 178 14 .73 Total 243 39 221 33 711 55 'Subject ate food in 37 minutes. CONCLUSIONS AS TO EFFECT OF INGESTING GLUTEN. The four experiments with gluten bread and skim milk all indicate a pronounced increment in the metabolism following the ingestion of the food, which in some instances continued for a 12-hour experimental period. This increment was shown not only in the gaseous metabolism and heat production, but also in the nitrogen excretion, which was INGESTION OF PROTEIN DIETS. 297 considerably above the basal value even at the end of the experiment. In three of the four experiments the nitrogen excretion in the urine was the highest in the third 2-hour period of the experiment. There was a distinct tendency, however, for the greatest increase in the heat output to occur in the first 4 hours of the experiment. PLASMON AND SKIM MILK. The glidine used in the protein experiments represented an approxi- mately pure vegetable protein; the gluten was also a vegetable protein. To study the effect of an animal protein, plasmon, a food material derived from milk, was given to the subject in two experiments. Bo experiments were made with the Middletown respiration calorimet in 2-hour periods. H. R. D., May 4, 1906. — In addition to 100 grams of plasmon, the subject took 70 grams of plasmon milk biscuit and 206 grams of skim milk. The total nitrogen intake was 15.07 grams, of which 11.92 grams came from the plasmon, 2.10 grams from the plasmon milk biscuit, and 1.05 grams from the skim milk. With this diet 36 per cent of the fuel value of the intake was derived from carbohydrates and but 54 per cent from protein. The basal value employed was the aver- age of determinations made between February 6 and April 20 of the same year. As may be seen from table 228, an increment in carbon- dioxide excretion was found in all four periods. The measurement of oxygen consumption was not obtained for the first period, but subse- quently a pronounced increment was observed. The heat pioduction also increased in the four periods and the nitrogen excretion was very TABLE 22S.—H. R. D., May 4, 1906. Sitting. (2-hour periods.) J'lasmon, plasmon milk biscuit, and skim milk: Amounts, 100 grams plasmon, 70 grams plasmon milk biscuit, 206 grams skim milk; nitrogen, 15.07 grams; total energy, 890 cals. Fuel value: Total, 758 cals.; from protein, 54 p. ct.; from fat, 10 p. ct.; from carbohydrates, 36 p. ct. Basal values (February 6 to April 20, 1906): COj, 47 grams; O?, 42 grams; heat, 146 cals. Nitrogen in urine, 0.77 gram per 2 hours (May 4, 1906). Time elapsed since subject Nitrogen in urine Carbon dioxide. Oxygen. Heat. Respira- finished eating.1 per 2 hours. Total. Increase. Total. Increase. Total. Increase. tory quotient. grams. grams. grams. grams. grams. ca/s. cals. 0 to 2 hours . . . 1.58 61 14 172 26 2 to 4 hours . . . 2.12 62 15 54 12 177 31 0.83 4 to 6 hours . . . 2.14 56 9 47 5 153 7 .87 6 to 8 hours . . . 1.81 55 8 52 10 159 13 .76 Total .... 234 46 153 227 661 77 ^Subject ate food in 36 minutes. Increment of oxygen 2 to 8 hours after food. 298 FOOD INGESTION AND ENERGY TRANSFORMATIONS. considerably increased. The body-temperature approximated 36.7° C. ; the pulse rate averaged 65 and the respiration rate 19. The ingestion of the 15 grams of nitrogen in this diet thus resulted in a pronounced increase in the metabolism, which continued for at least 8 hours. H. C. K., May 15, 1906. — Plasmon graham biscuit was substituted for the milk biscuit used in the previous experiment, the amounts being 100 grams plasmon, 47 grams plasmon graham biscuit, and 439 grams skim milk. The total nitrogen intake was practically the same as in the first experiment, i. e., 15.25 grams, with 11.92 grams from the plasmon, 1.07 grams from the biscuit, and 2.26 grams from the skim milk. The experiment was lengthened to 12 hours in order to obtain the total effect of the food. The results of the experiment are given in table 229, which shows that the increment in carbon-dioxide pro- duction persists throughout the entire experiment. The values obtained for oxygen consumption were variable, as is indicated by the great irregularity in the respiratory quotients. The possibility of a compensation can hardly be considered here and the variations are undoubtedly due to some technical difficulty. The measurements of the heat production show positive increments during the first three periods, with values lower than basal in the fourth period, an increment in the fifth period, and a value lower than basal in the sixth period. The nitrogen values are characteristic, with a maximum in the third period. The body-temperature averaged 36. 7° C.; the pulse rate averaged 51 and the respiration rate 18. Unfortunately the results obtained in this experiment do not permit definite conclusions regarding TABLE 229.— H. C. K., May 15, 1906. Sitting. (2-hour periods.) Plasmon, plasmon graham biscuit, skim milk: Amounts, 100 grams plasmon, 47 grams plasmon graham biscuit, 439 grams skim milk; nitrogen, 15.25 grams; total energy, 862 cals. Fuel value: Total, 728 cals.; from protein, 56 p. ct. ; from fat, 8 p. ct. ; from carbohydrates, 36 p. ct. Basal values (May 3, 1906): COa, 51 grams; Oa, 47 grams; heat, 164 cals. Nitrogen in urine, 0.97 gram per 2 hours (May 15, 1906) -1 Time elapsed since subject Nitrogen in urine Carbon dioxide. Oxygen. Heat. Respira- finished eating.2 per 2 hours. Total. Increase. Total. Increase. Total. Increase. tory quotient. grams. grams. grams. grains. grams. cals. cals. t to 2i hours 1.53 62 11 59 12 191 27 0.77 2i to 4J hours 1.86 66 15 47 0 179 15 1.01 4i to 6J hours 2.04 63 12 58 11 178 14 .79 6t to 8J hours 1.79 53 2 50 3 160 -4 .76 8J to 10i hours 1.63 54 3 39 -8 180 16 1.01 10i to 12i hours 1.38 57 6 53 6 158 -6 .79 Total.... 355 49 306 24 1,046 62 'Sample included amount for about 1 hour from the time subject began to eat food. ^Subject ate food in 34 minutes. INGESTION OF PROTEIN DIETS. 299 either the amount or the duration of the effect upon the metabolism due to the ingestion of this amount of nitrogen. The general effect of 100 grams or more of plasmon, together with 200 c.c. or over of skim milk, is to increase the heat output considerably above the basal metab- olism for at least 10 hours. SUMMARY OF RESULTS OF EXPERIMENTS ON INGESTION OF PROTEIN. A general examination of the details of the experiments discussed in the preceding part of this section shows conclusively that following the ingestion of protein there is a distinct increase in the metabolism which may persist for a considerable period of time. In an attempt to establish a quantitative relationship between the amounts of protein ingested and the subsequent increments in the metabolism, and like- wise to study the time relations, we have summarized in table 230 the results of the calorimeter experiments. The data for heat produc- tion in the respiration experiments have already been presented in table 215. (See page 284.) Most of the experiments were made with animal protein, these including the large number in which beefsteak was ingested. Even the beefsteak experiments in which small amounts of bread and potato chips were taken may, for reasons previously discussed, be considered as primarily animal-protein experiments. The experiments with plas- mon and skim milk likewise showed the influence of animal protein upon the metabolism. In the experiments with gluten bread and skim milk the effect of a combination of vegetable and animal proteins was studied, but the greater part of the nitrogen was supplied by the gluten. The only experiments with pure vegetable protein were those with glidine, but with two exceptions the amounts of nitrogen in the glidine ingested were relatively small. It is somewhat difficult to present in tabular form the results of experiments extending over a period of many years, which were made with different apparatus, very considerably different amounts of food, and varying experimental periods. The table is, however, reasonably self-explanatory. Special attention should be called to the consider- able variations in the length of the individual periods in the experi- ments, these being shown in the first column with the initials of the subject. In all cases they were 2 hours, 1 hour, or 45 minutes in length. The total increments in carbon-dioxide production, oxygen consump- tion, and heat production during the entire period of observation are given in the next to the last column ; in the last column may be found the percentages of increment above the basal values for the same peri A positive increment was obtained in all of the experiments except in that with F. M. M., January 20, 1910. Even in this experiment 300 FOOD INGESTION AND ENERGY TRANSFORMATIONS. d u *= rH IO rH CO t- IO Tt< OJ rH o o t» «9t-W ojoo^. OJ * ^ 0 rH N 0 CO (N O CM rH 03 S s Q. (D ^ O | rH rH rH i o EH Amount. CO CO CO co ^ co rH iO iO (N oo t>. o CM rH t~. O CM iO (N CO ^ r,§ sis iO IO IO O iO iO ^^ IO t'* ^* rH f^ CM l>* l"^ rH rH I | rH rH rH ^ — — • CO CO ^ rH rH rjl "3 "3 •*? « O Qj •2 ^ tt_i , ||g (H GO v-5 o oo 10 ^5 ^^ ^? O CO IN O OO iO ^5 ^^ ^S O CO (N 9 9 o o O O O iO iO iO lOCOiOiOCOiOCMOOO IO O CM IO O CO rH O CS *» •c 1 o •*-» •O O O V CO ^ 6j o ft III • • • "S d O O 2 * 5 iO — ^_ ^ .. ^^ -. __ ft. S 03 1 1 1 ""* •1 0 Qj <, IN O5 IO rH CO O CM t^ rH rH CO rH O O i— 1 rH IO 1 1 1 iO O O iO IO IO IO O »O O OrHCMCMrHCOrH^flO II II iO iO CM •<* CO 1 Increas co 00 CO rH rH rH Tf CO rH CM rH rH CO TJ* CO O^ rH 01 co oo rH rH o o O IO iO *O *O O O O • J o »o OiO O O O iO O *C O iO 10 s CM CO GO OJ rH (N CM CO CO rH rH IN i-t (N IO O CO rH rH rH ^.rHCM CO C-l O C^ C$ ^ CO CO t^* CO rH CO rH 1 rH O CO rH IN rH CO O CO CO ^ 1 Oi <-N rf< O iO IO O "3 o! PQ "a ^H CO ^^ to rt< CO rH O rH IO iO -^ IO rH rH CO ^ iO ^t CO rH O rH IO rH CMc3£ iO ^™^ t*» o^ o^ t^* ^O d ^O CO CO C^ tO ^^ pQ OICMt-INCMCCCMNt- co co o CM CM CO _c -o V 1 s a "§ II 8, SC3 03 M £_' || g 111 111 | c3 PH 03 0) a 6 OJJ 0 W w w 03 OO aj o w +3 OHH w c-l -M e3 O O « o w 8°w O W +s -*J *J OO "^OO a'OO * o Wo Wo W ooj o W 230.— Su a o w 0 o •M § °° t3 C°- o> *° CD CO rH CD oo o CO rH t» OJ OJ iO iO O IO O CM os o r- OJ d 3 i ia a o a s 1 IV. t-- IO CO CO co CO 00 rH rH 00 CM CO O CO CO CM rH rH 11 CO O CM •c s "« £ •c (i "t .i £ E a 1 "8 4d 11 _.« fe a 03 ^i t^ r\i o o S Q) M c. . 1 • 91 OJ o, rH CM r* . on s-s OJ Ol 00 • o • O5 ,—t ^H ^ > rH S^ CU 15 Or? s . 8-. i% Id! ^ • CM rH . Beefsteak and brea Jan. 11, 1910.. F. M. M., 1 hr INGESTION OF PROTEIN DIETS. 301 O OS CO «O t~- rH Tf OO C^ rH I-H rfri Ol rH I— I rH rH OO O 1C 1C 1C 1C 1C I— I i— C i-H rH 1C rH rH CO I— I 1— ITj< Ol ^O ^D Oi ^O ^D 00 O^ C^ £O OJ O'l CO CO ^H <^5 CO ^^ -_ Is" t** ^* CO ^^ Oi ?O OOOOCOCD!N-<*CM ol rH CO W rH « tN ' (NrH IN ... 1 . • O O 0 ... 1 . • 1C »C - - - O (N t>. • a a-* 3-2 ^5^ r^ o> • O< 3 Of iC O O »C C rH !N CO CO •* o >c O rH X m O o, * M -^ S t o I •-3 o c9 ja •O >- J*® * d |-3 TJ > •3J "" II a -a c9 u o ••-• b. a u -•9 ^•3 o *? •—. O rn op ic p •-> IN CO CM rH 1C OO O OO ICO >C >C O >C »C O diCOlCNCOOSiCiCCN U5 1C O O >C O IN O Tf CO M O»C OO OO OO OO © »C O O •* 1C «D « «O CO O»C ICO >CO iCO iCO O- >CO >C»C COOOit'lii-iO •OOi-iCOt»>C»C • IN O 1C O O tJ TJI QO «O CO OO «C»C 10 O OO O>C »n ip ic p «O CO O tO CO O CN OJ QC Ol CN 00 ic p pp »c p pp op p ic rHrHCDrHi— 1^<1— IrHTjIINrHCOrHrHIC (NCNI OO iCO *• v *~^ m ^~ •« x— v oo ail ail ei pj -4 o o « oo ® O EO K aa^ss^ss^sE^ss03 sa°3asa3Bs°isas3a0o3 -4^> +J -4^> -fc? ^~ -t— -^ +J -r? *- WMC3MMOJMM03MM03MMC3 ^MggcJWpaMWQjMM^MMgJ OO^'OO^OOisOOi'OOii' OO^OO cuOOtuOOcuOOai o wo wo wo wo w o wo wo wo wo w OS OC IO 1C 35 OS O> 00 O o O O5 co Ol 1< (N CO IN CO O t> O (N CO O t>- Os O GO O5 CC -H Tf< O w . DQ a w 5 -^2 m Pi / DQ a OQ o. COO 33 CM •Jl — CO O (N . OQ g. IS 0 • ft 1C O 01 -^ OQ a 13 U Q& ff\ O 01 1C O »C O t>» ^ t>» . SH d "^ rH rH Os 03 a on -<' . ^ •a — * CM 03 r • 1-5 fo ,5-0 o __ c* "~ o>" j_j --1 ^ -5 302 FOOD INGESTION AND ENERGY TRANSFORMATIONS. VJ a "SS t I to ^2 a -a s "S § o CO IN B m 1 $ "o rt OH O) c» S 5 *H 1-4 rH *H C^) *-* rH *H F-l ^f r-^ CO CD O» « - 1 "o3 o 2 .§ H •< 8SS388S83S8S8 co t*^ i^ G% ^* o^ ^^ O^ t^ ^^ C^ CD U •*•< 1 — — <2 ° > > o, ° OOOOr» "* 0 m rH i-H rH C4 rH 00 O CO IN CO •* rH rH j S § CO d "5 O5 *C t^ CM rH ^ rH rH rH „ «3s«Sfc3-8S-3 »C CN rH 1C O IO rH rH CO rH rH i— ( 1-4 ^H i-H C-i l-H CO »H •* • CO rH IN b- rH • IN rH rH C< 1| fe'S rH rH rH rH t^* C^l CO rH ts. -^ rH ' rH : : ^ : : ^ : : ^ : : ^ . .0 : :0 s-g -S *"* S 1,1 S 01 M 60 o- M M O^ fo I-* a N^aj e-ie*j3 c-i^nj C4.M53 o wo wo Wo w do|oo| o Wo W d . H g.s j^ iO iO ^* CO Co rH rH (>1 rH N- >O O -, O t- • £ 3 fi8 , rt c3 c3 ^^c^J §| g 'g § N 2 M o ~ ^ . : |I^Q aw 0 03 •a o a o o 5 *s g S -«-> CO 'd a a a . 11 J-S eS CO CM £> +i I'S -^^ -a o d sll n „ S I S-B. S d 2 8 «> a a

o — • a — • ' "^ -^ .. ^ OQ •2 S oS -9 HHH — CM CO ^ INGESTION OF PROTEIN DIETS. 303 there was an increment of 10 calories in the heat production, but the values for the carbon-dioxide production and the oxygen consumption both present slight negative values. An examination of the details of the experiment shows that positive increments occur in the first two periods, these amounts being counterbalanced by negative values in subsequent periods. In the first two experiments given in table 230 the food taken had practically the same nitrogen content and the experiments may therefore be considered as duplicates, although with different subjects; both indicate a considerable increase in all of the three factors. In the next two experiments, which were made with the same subjects, the food taken was approximately one-half that ingested in the preceding experiments; the increments found were proportionally smaller than those in the first two experiments. In both pairs of experiments, the values for A. W. W. are lower than those for A. H. M., especially for carbon-dioxide production and heat production. From these four experiments, therefore, one may infer that the influence of the ingestion of beefsteak is by no means the same with different individuals. The values for oxygen consumption for the two subjects are considerably at variance, as in the high-nitrogen experiments the increments are alike, while with the low-nitrogen intake the increment for A. H. M. was but half that with A. W. W., thus showing the difficulties in comparing results by direct and indirect calorimetry for experimental periods less than 24 hours. In comparing the data for exiperiments such as these, we should expect to find that each gram of ncrement in carbon dioxide produced would correspond to an increment in heat production of 1\ to 3 calories. An examination of the results in table 230 shows that this ratio holds true in but few instances. Thus, in the first four experiments the amount is more nearly 2 calories per gram of carbon dioxide than 3 calories; this is true, also, for many other experiments. In the experi- ment with V. G., January 21, 1911, we find that the ratio is 7 calories per gram of carbon dioxide, while in the following experiment it is only 1.2 calories, and in the two succeeding experiments the ratios are less than 1 calorie. Such irregularities as these discredit the use of direct calorimetry in short experiments. On the other hand, when the computations of indirect calorimetry are based upon carbon dioxide alone, they are open to the serious objection that the increase found may be due to change in the character of the katabolism or to a forma- tion of fat from carbohydrate, but when the measurements are made by direct calorimetry it provides positive evidence that the increment in heat production is due to the food alone. The data for heat produc- tion in table 230 show that such an increment was found in every experi- ment in which protein food was ingested, although in some cases the increment was very small. 304 FOOD INGESTION AND ENERGY TRANSFORMATIONS. For a true comparison of the results of the different experiments, it is necessary to compare only those in which approximately the same amounts of nitrogen were ingested and with experimental periods of approximately the same length. In many instances the total effect of the food had by no means ceased at the end of the period of observa- tion. In other experiments it was evident that the full effect of the food ingestion was obtained, inasmuch as increments of less than 0.5 gram, as well as negative values, were found in the later periods. It was hoped that some information might be obtained as to the rela- tionship between the amount of nitrogen ingested and the increments in the metabolism. Generally speaking, the larger amounts of meat produced the larger increments. This may not hold true, however, when different individuals are used for subjects, as may be seen by a comparison of the experiment with A. W. W., April 6, 1907, in which 755 grams of meat were ingested, with that with J. R., December 4, 1908, in which 418 grams were taken. Although both of the experi- ments continued for 8 hours, the increment in heat production was slightly more in the second experiment than in the first, but the incre- ment in oxygen consumption and carbon-dioxide production in the experiment with J. R. was about 70 per cent of that in the experi- ment with A. W. W. It will thus be seen that marked irregularities occur in all these experiments, and no constancy was found in com- parisons with different individuals and rarely in comparisons for the same individual. It was also hoped that some light could be obtained as to the influ- ence of animal protein as compared with that of vegetable protein. A superficial examination of the data in table 230 shows no material difference in the two classes of proteins in their influence upon the metabolism, but here again the comparisons are complicated by the fact that the experiments are made with different individuals and with different experimental plans. With the purest protein substance used (glidine), the experiments in which the largest amount was given, i. e., 9.70 grams of nitrogen, gave duplicate values for the same subject which were only reasonably satisfactory. Comparing these values with those obtained with beefsteak or with beefsteak combined with potato chips or bread, in which essentially the same amount of nitrogen was ingested, we find that the average values with glidine are slightly higher than those for beefsteak, although even with the same amount of nitrogen the values with beefsteak vary widely. The gluten bread experiments, while complicated by a relatively small amount of animal protein in the form of skim milk, show increments comparable with those obtained with beefsteak. One must conclude, therefore, that these experiments, defective though they are, indicate that there is no clearly defined difference between animal and vegetable proteins in their influence upon the metabolism. INGESTION OF PROTEIN DIETS. 305 The series of respiration experiments which are summarized in table 215 were made subsequent to most of the calorimeter experiments included in table 230 and were designed to throw more light upon the quantitative relationships. Varying amounts of beefsteak were taken in these experiments, although in none was so large an amount eaten as in the first two calorimeter experiments given in table 230. The heat production in the periods subsequent to the taking of the food invariably exceeded the basal value. Usually the experiments were not continued sufficiently long to include the total effect of the food, so that the basal value would again be reached; consequently the increases recorded in the last two columns of table 215 frequently represent incomplete increments. Most of the experiments did not extend over a period longer than 6 hours, although in one case the observations were continued over a period of nearly 12 hours. The irregularity in the effect upon different individuals of the ingestion of the same amount of nitrogen is strikingly shown in the percentage increase above the basal value, these figures being given in the last column of the table. While theoretically we should expect to find con- tinually decreasing values for these percentages, as the experiments are arranged in the table in the order of decreasing amounts of beef- steak eaten, this is not actually the case. Making due allowance for the fact that the time over which the experiments were continued varies somewhat, it is still clear that there is no uniform relationship between the amount of nitrogen ingested and the actual increase above the basal metabolism. Whether such a relationship could have been established if the experiments had been continued until the effect of food had completely ceased would appear, from the data obtained, extremely improbable. Experiments of this length are very tiresome for both subject and observer; nevertheless such experiments should ultimately be made. For the present, there- fore, we can only reiterate the deductions made from the results of the calorimeter experiments to the effect that while the ingestion of protein in almost any amount invariably produces an increase over the basal metabolism which may be 25 per cent for several hours and for short periods may rise to 45 per cent (see tables 198 to 229), no definite mathematical relationship between the amount of protein ingested and the increment in the total metabolism can be noted from these values. It is probable that in any study of these results it should be remembered that these subjects were unlike in body-weight and in active mass of protoplasmic tissue. 306 FOOD INGESTION AND ENERGY TRANSFORMATIONS. INGESTION OF MIXED NUTRIENTS. Studies with a single mixed nutrient were made with but one food material, this being whole milk. In addition, two experiments were made in which the milk was combined with one other food material, and in a considerable number of experiments the metabolism was measured after a diet such as would be taken in one or more ordinary meals. MILK. No other single food material contains the three important nutrients, protein, fat, and carbohydrate, in such relatively well-balanced propor- tions as whole milk does. Three calorimeter experiments and one respiration experiment were made to study the effect upon the metab- olism of the ingestion of milk. Statistical data not included in the tables or in the discussion of the experiments are as follows : H. R. D., 8h40m a. m. to 4h40m p. m., March 21, 1908. 59.2 kilograms.— During experiment sat very quietly, reading about four-fifths of time; very drowsy at 10 a. m. Urinated 6h50m a. m., Ilh40m a. m., and 4h55m p. m.; defecated (after enema) about 7h20m a. m. Body-temperature: 36.95°, 36.69°, 36.71°, 36.71°, 36.69° C. Pulse rate, 63; respiration rate, 19. A, L. L., 8h40m a. m. to 4h40m p. m., March 22, 1906. 68.3 kilograms.— Urinated 7h20m a. m. and 4h57m p. m. Sat very quietly reading; not sleepy except near end of experiment. Body- temperature : 36.72°, 36.65°, 36.70°, 36.64°, 36.53° C. Pulse rate, 61; respiration rate, 19. A. H. M., 8h30m a. m. to 4h30m p. m., March 23, 1906. 67.0 kilograms.— Urinated 6h30ra a. m., 12h40m p. m., 4h45m p. m. Read very little, and sat quiet in chair; drowsy, especially in afternoon. Body-temperature: 36.59°, 36.44°, 36.42°, 36.44°, 36.33° C. Pulse rate, 53; respiration rate, 16. H. F. T., 10h21m a. m. to 2h15m p. m., July 14, 1911. 57.9 kilograms.— Milk experiment on this day preceded by observations of the gaseous exchange 8^ hours after ingestion of beefsteak. (See page 286.) Tired and restless in fifth period. Nitrogen in urine per hour 7 a. m. to 10h40m a. m., 0.69 gram; 10h40m a. m. to 2h20ra p. m., 0.72 gram. CALORIMETER EXPERIMENTS. In the calorimeter experiments with milk, a study was made of the influence of approximately 600 grams of whole milk, in which 19 per cent of the fuel value came from protein, 52 per cent from fat, and 29 per cent from carbohydrates. These experiments were carried out with three subjects on successive days with the Middletown respiration calorimeter. As was usual with these earlier experiments, the only basal values obtainable were determined several days or weeks before or after the food study and hence are not ideal for purposes of com- parison. The observations were all made in 2-hour periods. H. R. D., March 21, 1906. — The data obtained following the inges- tion of 599 grams of milk and 9 grams of lime-water, with a fuel value of 444 calories, are given in table 231. These show an increment in carbon-dioxide production in all of the periods, with but 1 gram in the last period. The values for oxygen consumption were irregular, but INGESTION OF MIXED DIETS. 307 a positive increment for the total experiment was obtained of 4 grams. The greatest increment in heat production was in the first period, with variations above or below basal thereafter. The influence of this amount of milk upon the metabolism of the subject was therefore relatively slight. The urine was collected but once for the experiment, and showed an average excretion of 0.86 gram of nitrogen per 2 hours. TABLE 231.— #. R. D., March 21, 1906. Sitting. (2-hour periods.) Milk (whole): Amount, 599 grams;1 nitrogen, 3.17 grams; total energy, 471 cals. Fuel value: Total, 444 cals.; from protein, 19 p. ct. ; from fat, 52 p. ct. ; from carbohydrates 29 p. ct. Nitrogen in urine, 0.86 gram per 2 hours.2 Basal values (February 6 to April 20, 1906): COa, 47 grams; 62, 42 grams; heat, 146 cals. Time after food. Carbon dioxide. Oxygen. Heat. Total. Increase. Total. Increase. Total. Increase. 0 to 2 hours grams. 50 51 50 48 grams. 3 4 3 1 grams. 40 43 47 42 grams. -2 1 5 0 cals. 156 146 149 144 cals. 10 0 3 -2 2 to 4 hours 4 to 6 hours 6 to 8 hours Total 199 11 172 4 595 11 'Also 9 grams lime-water. 2Sample included amount for about 1 J hours without food preceding experiment. A. L. L., March 22, 1906. — The details of the experiment are given in table 232. The subject drank 598 grams of milk, combined with 9 grams of lime-water, with a fuel value of 382 calories. In the experi- TABLE 232.— A. L. L., March 22, 1906. Sitting. (2-hour periods.) Milk (whole): Amount, 598 grams;1 nitrogen, 3.15 grams; total energy, 410 cals. Fuel value: Total, 382 cals.; from protein, 19 p. ct.; from fat, 52 p. ct. ; from carbohydrates, 29 p. ct. Nitrogen in urine, 0.83 gram per 2 hours.2 Basal values (April 3 and 6, 1906): CCh, 47 grams; O?, 43 grams; heat, 145 cals. Time after food. Carbon dioxide. Oxygen. Heat. Total. Increase. Total. Increase. Total. Increase. 0 to 2 hours. . . grams. 59 54 50 45 grams. 12 7 3 _2 grams. 44 45 45 44 grams. 1 2 2 1 cals. 172 166 153 148 cals. 27 21 8 3 2 to 4 hours 4 to 6 hours 6 to 8 hours Total. . . . 208 20 178 6 639 59 1Also 9 grams lime-water. 2Sample included amount for about lj hours without food preceding experiment. 308 FOOD INGESTION AND ENERGY TRANSFORMATIONS. mental period of 8 hours, the total increment for carbon-dioxide pro- duction was 20 grams, for oxygen consumption 6 grams, and for heat production 59 calories. The only basal values available were those determined 12 and 15 days subsequent to the food experiment. Never- theless it is evident that the increment with this subject was materially greater than with the subject of the preceding experiment. A. H. M., March 23, 1906. — Following the ingestion of 599 grams milk and 8 grams of lime-water, with a fuel value of 385 calories, an increment was obtained in the carbon-dioxide production in the first three periods, with a value below basal in the fourth period. (See table 233.) The oxygen consumption was somewhat irregular and also showed values below basal in the fourth period, with a total increment of 11 grams for the 8 hours. The heat production in the first three periods increased measurably, but here again a value below the base-line was obtained in the last period. It is significant that in the fourth period values below basal are observed for all of the three TABLE 233.— A. H. M., March 23, 1906. Sitting. (2-hour periods.) Milk (whole): Amount, 599 grams;1 nitrogen, 3.17 grams; total energy, 412 cals. Fuel value: Total, 385 cals.; from protein, 19 p. ct. ; from fat, 52 p. ct. ; from carbohydrates, 29 p. ct. Nitrogen in urine, 1.25 grams per 2 hours.2 Basal values (February 12 and 14, 1906): CC>2, 45 grams; Oz, 40 grams; heat, 142 cals. Time after food. Carbon dioxide. Oxygen. Heat. Total. Increase. Total. Increase. Total. Increase. 0 to 2 hours grams. 53 51 51 41 grams. 8 6 6 -4 grams. 46 1 90 35 grams. 6 10 -5 cals. 170 /157 \155 137 cals, 28 15 13 -6 2 to 4 hours 4 to 6 hours 6 to 8 hours Total. 196 16 171 11 619 61 'Also 8 grams lime-water. 2Sample included amount for about 2 hours without food preceding experiment. factors of metabolism, strongly implying that the basal value deter- mined on February 12 and 14, 1906, was erroneous and that a true basal value for this day would have been nearer to that found in this period of the experiment. In that case the increment due to the inges- tion of milk would have been greater than here recorded. It is clear that even with this imperfect base-line there was a very measurable increment due to the ingestion of milk, especially in the first three periods. Since the total nitrogen intake was but 3.17 grams, it is probable that this effect upon the metabolism should not be ascribed solely to the protein in the milk. In our study of the effect of carbo- INGESTION OF MIXED DIETS. 309 hydrate ingestion, lactose, which is present in milk in considerable amounts, was noted as having a positive effect upon the metabolism; hence we probably have here a summation effect of the protein and lactose. While the three experiments as a whole are not especially satisfactory as duplicate experiments, they are uniform in indicating a positive increment due to the ingestion of milk. RESPIRATION EXPERIMENT. Only one respiration experiment was made with milk, this being a part of the later investigations in Boston. The universal respiration apparatus was employed, with experimental periods of the usual 15- minute length. The basal value was determined in several periods immediately preceding the taking of the food. H. F. T., July 14, 1911. — The amount of milk taken by this subject was 500 grams, with a fuel value of 358 calories. This energy content was somewhat less than that of the milk used in the calorimeter experi- ments, although derived from the three nutrients in the same propor- tions as in those experiments. The details of the experiment are given in table 234. The maximum increase in metabolism, which occurred inside of the first hour, was relatively slight, the heat pro- duction rising from 0.91 to 1.01 calories per minute. The basal value was reached in 3 hours. Although unaccompanied by respi- ration experiments with other subjects or with the same subject, the results of this experiment are of interest for comparison with the data obtained in the calorimeter experiments with this common food material. TABLE 234. — H. F. T., July 14, 1911. Lying. (Values per minute.) Milk (whole): Amount, 500 grams; nitrogen, 2.64 grams; total energy, 381 cals. Fuel value, 358 cals.; from protein, 19 p. ct.; from fat, 52 p. ct.; from carbohydrates, 29 p. ct. Time. Average respiration rate. Carbon dioxide. Respira- tory quotient. Oxygen. Average pulse rate. Heat (com- puted) . Without food:1 Av of 3 periods 10 C.C. 151 0.80 c.c. 189 44 cals. 0.91 With food:2 10h21m am 10 153 .73 209 45 .99 10 57 a.ni 10 177 .86 207 43 1.01 11 24a.m 11 171 .83 205 45 .99 1 1 55 a.m . 10 161 .83 195 44 .94 12 39 p.m 10 164 .86 191 .93 1 15 p.m 10 158 .82 193 43 .93 2 00 p.m 11 160 .84 191 43 .93 'Subject had eaten 206 grams beefsteak at 12 midnight, July 13. 'Subject drank milk between lO'W" and 10b10m a. m. 310 FOOD INGESTION AND ENERGY TRANSFORMATIONS. MIXED DIET. While the study of specific food materials is of abstract physiological value, especially those containing but a single nutrient like the sugars in our study of the carbohydrates, nevertheless the most practical interest lies in the influence of a mixed diet upon the basal metabolism. We have for consideration in this connection the results of 15 experi- ments in which the metabolism was studied after a mixed diet. Of these, 13 were calorimeter experiments and 2 were respiration experi- ments. The composition of the diet used in these 15 experiments is given in table 235. Additional evidence as to the influence of a mixed diet upon the metabolism is also given in an abstract of four calo- rimeter experiments, previously published, which followed several days of fasting. TABLE 235. — Percentage composition of mixed diets used in experiments. Subject and date. Protein. Fat. Carbo- hydrates. Fuel value per gram. A. H. M. .Feb. 2- 3, 1906 p. ct. 4.01 p. ct. 4.51 p. ct. 12. 11 cals. 1.0871 D. W Jan. 12-14, 1906 5.2 3.2 24.1 1.531 H. R. D..Dec. 7-8,1905 3.9 3.8 12.2 1.038 N. M. P.. Dec. 11-12, 1905 4.8 4.7 19.7 1.448 H. L. H . . June 14, 19102 4.21 3.71 22. 5l 1.4321 A. L. L. . .Feb. 13, 19062 5.31 11. 7l 13. 91 1.873 A. L. L. . . Feb. 15, 19062 . 4.51 9.81 14. 31 1.640 A. H. M..Feb. 16,1906 6.81 14. 4l 18. 91 2.461 A. H. M. .Feb. 19, 1906 7.71 14. Ol 19. 51 2.410 H. R. D . . Feb. 17, 19062 5.41 8.71 12. 91 1.641 H. R. D. .Feb. 21, 19062 6.21 12. Ol 14. 31 2.017 A. L. L. . . Apr. 6- 7, 19062 4.4 10. 81 15. 3l 1.815 H. R. D..Apr. 10-11,1906 7.1 14. 6l 12. 91 2.201 J. J. C... .Feb. 28, 191 13 2.9 3.01 14. 71 1.0031 A. F. . Apr. 20, 1915 5.51 7.61 10. 21 1.3601 'Computed. 2Diet on this day also included sugar, for which the composition is, carbohydrate, 100 p. ct. and fuel value, 3.960 cals. per gram. *For composition of black bread used in diet of this day, see table 50, page 124. Sugar in the diet is not included in the composition here given. CALORIMETER EXPERIMENTS. In our earlier investigations with the respiration calorimeter in Middletown practically all of the experiments following a 2-days' fasting experiment were with mixed diet. These have already been considered in a previous section of this report, in which the metabolism during fast and after food as measured in 24-hour periods was discussed.1 It is desirable, however, to group them in abstract here with other calo- rimeter experiments with mixed diet not yet discussed. In two of the mixed-diet experiments, but two food materials were used, one of the pp. 52 to 72. INGESTION OF MIXED DIETS. 311 experiments being with crackers and milk and the other with cereal and milk. In 8 experiments excessive amounts of food were taken, either as breakfast or supper. In all but one of the calorimeter experi- ments the measurements were made with the Middletown respiration calorimeter. The experiment with H. L. H. was made with the bed calorimeter in Boston. In the first four experiments discussed the determinations were made in 24-hour periods. The basal values in all cases were determined on some other than the experimental day. A. H. M., February 2-3, 1906.— For the experiment with 70 grams soda crackers, 50 grams graham wafers, and 1,030 grams whole milk, a basal value was used which was obtained in November 1905. (See table 22, page 70). The fuel value of the diet was 1,250 calories, of which 15 per cent came from protein, 39 per cent from fat, and 46 per cent from carbohydrates. The ingestion of this food in three portions during the day resulted in an increment of 149 grams in carbon-dioxide production, 80 grams in oxygen consumption, and 239 calories in heat production. The doubtful expediency of employing a basal value so far removed from the values obtained in the food experiment has already been discussed in our previous consideration of these results and need not be further emphasized. The main point to be noted here is the fact that the crackers-and-milk diet resulted in an increment of approximately 14 per cent in the heat production. D. W,, January 12-14, 1906. — The subject took 166 grams of a dry cereal and 450 grams of whole milk each day in three portions. (See table 13, page 62). This diet had a fuel value of 943 calories, of which 14 per cent came from protein, 20 per cent from fat, and 66 per cent from carbohydrates. The basal value used was determined in a fasting experiment of two days preceding the food experiment. On the first food day there was only a slight increment over the basal average value, the metabolism being essentially the same as that on the last day of the fast. On the second day with food there was a considerable increment in the metabolism, which amounted for the heat production to 184 calories. Here again we must call attention to the previous discussion as to the errors involved in the used of a base-line of this character. It is clear, however, that the ingestion of the food arrested the fall in the metabolism incidental to fasting and finally produced a rise. H. R. D., December 7-8, 1905. — The diet consisted of 125 grams orange juice, 1,427 grams milk, 181 grams of a dry cereal, 128 grams eggs, and 149 grams apples. This amount of food was taken in three portions at the ordinary meal times. (See table 11, page 61). The basal value used for comparison was determined in a 2-day fast imme- diately preceding the food day. The fuel value of the diet was 2,086 calories, of which 16 per cent came from protein, 35 per cent from fat, and 49 per cent from carbohydrates. The ingestion of this amount of 312 FOOD INGESTION AND ENERGY TRANSFORMATIONS. food resulted in a positive increase in metabolism, as shown by the total increment in the heat production of 189 calories, or approximately a 10 per cent increase. N. M. P., December 11-12, 1905. — The food intake in this experiment (see table 12, page 61) was much larger than in that with H. R. D., the diet consisting of 260 grams orange juice, 97 grams dry cereal, 914 grams milk, 233 grams bread, 13 grams butter, 634 grams cocoa, 179 grams eggs, 362 grams beans, 184 grams bananas, and 222 grams crackers, a total amount of 3,098 grams, with a fuel value of 4,486 calories. Of this energy, 14 per cent came from protein, 30 per cent from fat, and 56 per cent from carbohydrates. As in the preceding experiment, the food was taken in three portions at the usual meal times. The increase in heat production as a result of taking this food was 379 calories, or approximately 17 per cent. The nitrogen excre- tion also increased considerably. H. L. H., June 14, 1910. — The experiment with this subject differed considerably from the four previous experiments discussed in that it was but 5 hours long and the measurements were made with the bed calorimeter in Boston in 1-hour periods. The food, which was largely carbohydrates, was taken in one meal (supper) approximately 1£ hours before the beginning of the measurements. It consisted of 226 grams rolls, 97 grams sugar cookies, 44 grams sugar, 296 grams strawberries, and 468 grams milk. The fuel value of this diet was 1,731 calories, of which 68 per cent came from carbohydrates, 21 per cent from fat, and 11 per cent from protein. The basal value used for comparison was determined on the following day in a series of quiet periods, which were alternated with restless periods to avoid the necessity of enforcing TABLE 236. — H. L. H., June 14, 1910. Lying. (1-hour periods.) Supper (mixed diet): Amount, 1,131 grams; nitrogen, 7.31 grams; total energy, 1,794 cals. Fuel value: Total, 1,731 cals.; from protein, lip. ct. ; from fat, 21 p. ct. ; from carbohydrates, 68 p. ct. Nitrogen in urine, 0.34 gram per hour. Basal values (June 15, 1910) : CC>2, 25 grams; C>2, 22 grams; heat, 68 cals. Time elapsed since subject finished eating.1 Carbon dioxide. Oxygen. Heat. Total. Increase. Total. Increase. Total. Increas. 1J to 2i hours. . grams. 34.5 37.0 30.5 36.0 25.6 grams. 9.5 12.0 5.5 11.0 0.5 grains. 25.0 27.0 25.5 22.0 19.0 grams. 3.0 5.0 3.5 0.0 -3.0 cals. 83 05 92 80 67 cals. 15 27 24 12 -1 2J to 3i hours 3J to 4J hours 4i to 6J hours 5J to 6J hours Total 163.5 38.5 118.6 8.5 417 77 INGESTION OF MIXED DIETS. 313 muscular rest for too long a time. This alternation is in accordance with the usage of Professor Johansson and was our first attempt to employ his method. The data for these quiet basal periods are given in table 237. The results obtained in the food experiment, which are given in table 236, show an increment in the carbon-dioxide production for practically 5| hours after the food was given. The oxygen con- sumption also showed an increase in the first three periods, while the heat production continued above the basal value in 4 periods. Basal values were obtained for all the factors of metabolism in the last period of the experiment. TABLE 237. — Basal metabolism of subject H. L. H., June 15, 1910, in bed calorimeter.1 (1-hour periods.) Period. Carbon dioxide. Oxygen. Heat. 8h19ma.m. to 9h19ma.m grams, 26 0 grams. 23 0 cols. 71 10 19 a.m. to 1 1 19 a.m 25.0 22.0 68 12 19 p.m. to 1 19 p.m 25.0 21.0 69 2 19 p.m. to 3 19 p.m 26.0 22.5 64 4 19 p.m. to 6 19 p.m / 23.5 21.5 68 \ 23.5 21.5 68 Average 25.0 22.0 68 Nitrogen in urine per hour 9h40m a. m. to 8h25m p. m., 0.38 gram. HEAVY BREAKFAST. During the third week of February 1906, the Middletown respiration calorimeter was employed for studying the increment in the metab- olism due to the eating of a large amount of food. The meal selected for this purpose was breakfast, as it was believed that a subject could eat a larger amount at this time rather than at the end of the day, especially if his supper the night before had been light. Six experi- ments with three subjects were made on this plan; they were all 8 hours in length, with the measurements hi 2-hour periods. A. L. L., February 13, 1906. — The breakfast for this experiment consisted of 180 grams bread, 73 grams butter, 78 grams sugar, 311 grams oatmeal, 235 grams cream, 182 grams milk, 214 grams cocoa, and 92 grams eggs, a total amount of 1,365 grams. The fuel value of this food was 2,720 calories, 10 per cent of which came from protein, 52 per cent from fat, and 38 per cent from carbohydrates. The data for the experiment are given in table 238. The basal value used for comparison was drawn from three experiments within a week of the food experiment. The total increment was 61 grams in the carbon- dioxide production, 48 grams in the oxygen consumption, and 162 314 FOOD INGESTION AND ENERGY TRANSFORMATIONS. calories in the heat production. As the basal value for the heat pro- duction was approximately 600 calories for the 8 hours of the experi- ment, it will be seen that this increment of 162 calories corresponded to an increase in the metabolism of 27 per cent. There was no indi- cation that the stimulus to the metabolism had ceased at the end of the experiment, as even in the last 2-hour period there was an increase of 7 grams in the carbon-dioxide production, 8 grams in the oxygen consumption, and 26 calories in the heat production. It is evident that this excessive amount of food, although not so large as it was hoped the subj ect could eat, produced a prolonged increase in the basal metabolism. TABLE 238.— A. L. L., February 13, 1906. Sitting. (2-hour periods.) Heavy breakfast (mixed diet): Amount, 1,365 grams; nitrogen, 10.91 grams; total energy, 2,797 cals. Fuel value: Total, 2,720 cals.; from protein, 10 p. ct. ; from fat, 52 p. ct. ; from carbohydrates, 38 p. ct. Basal valves (February 7 to 20, 1906): CO2, 47 grams; Oz, 41 grams; heat, 151 cals. Time after food.1 Carbon dioxide. Oxygen. Heat. Total. Increase. Total. Increase. Total. Increase. 1 \ to 3 1 hours . grams. 74 63 58 54 grams. 27 16 11 7 grams. 60 50 53 49 grams. 19 9 12 8 cals. 201 204 184 177 cals. 50 53 33 26 3 ^ to 5 J hours . 5j to 7J hours. 7 j to 9J hours. Total 249 61 212 48 766 162 •Subject ate food in about 30 minutes. A. L. L., February 15, 1906. — Less food was taken in this experiment than in the experiment on February 13 with the same subject. The food eaten was 180 grams bread, 78 grams sugar, 323 grams oatmeal, 200 grams cream, 55 grams butter, 262 grams cocoa, and 98 grams eggs, a total of 1,196 grams. The fuel value of this diet was 2,142 calories, of which 9 per cent was derived from protein, 47 per cent from fat, and 44 per cent from carbohydrates. The results of the experiment are given in table 239. The carbon-dioxide increment continued for the entire experimental period, with a total increment of 49 grams. The oxygen consumption apparently reached its basal value in the third period, with a total increment for the experiment of 20 grams. The total increment in heat production was 96 calories, but the increase was but 5 calories in the last period. The total increase in heat pro- duction was approximately 16 per cent. A. H. M., February 16,1906. — The second subject used for this series of experiments was able to take much larger amounts of food than A. L. L. On this date he ate for his breakfast 72 grams potato chips, 148 grams peanut butter, 222 grams bananas, 319 grams oatmeal, INGESTION OF MIXED DIETS. 315 TABLE 239.— A. L. L., February 16, 1906. Sitting. (2-hour periods.) Heavy breakfast (mixed diet): Amount, 1,196 grams; nitrogen, 8 grams; total energy, 2,213 cals. Fuel value: Total, 2,142 cals.; from protein, 9 p. ct. ; from fat, 47 p. ct. ; from carbohydrates, 44 p. ct. Nitrogen in urine, 0.90 gram per 2 hours. Basal values (February 7 to 20, 1906) : CO2, 47 grams; Ch, 41 grams; heat, 151 cals. Time after food.1 Carbon dioxide. Oxygen. Heat. Total. Increase. Total. Increase. Total. Increase. 1$ to 3^ hours. grams. 70 63 52 52 grams. 23 16 5 5 grams. 54 48 38 44 grams. 13 7 -3 3 cals. 186 186 172 156 cals. 35 35 21 5 3| to 5£ hours. 5 i to 7 \ hours 1\ to 9$ hours Total 237 49 184 20 700 96 'Subject ate food in 20 minutes. 103 grams graham bread, 25 grams cheese, 139 grams whole wheat breakfast food (dry), 99 grams eggs, and 652 grams cream, a total of 1,779 grams. The fuel value was 4,378 calories, of which 12 per cent came from protein, 56 per cent from fat, and 32 per cent from carbo- hydrates. The data for the experiment given in table 240 show a striking rise in the carbon-dioxide production, with similar increases in the oxygen consumption and heat production, all of which continued throughout the experiment, with no evidence of a return to basal value, even in the last period. The total increment was 82 grams in carbon- dioxide production, 65 grams in oxygen consumption, and 186 calories in heat production. As the basal value for heat production was 568 TABLE 240. — A. H. M., February 16, 1906. Sitting. (2-hour periods.) Heavy breakfast (mixed diet) : Amount, 1,779 grams; nitrogen, 19.46 grams; total energy, 4,547 cals. Fuel value: Total, 4,378 cals.; from protein, 12 p. ct. ; from fat, 56 p. ct. ; from carbohydrates, 32 p. ot. Nitrogen in urine, 1.63 grams per 2 hours. Basal values (February 12 and 14, 1906) : CC>2, 45 grams; Oz, 40 grams; heat, 142 cals. Time after food.1 Carbon dioxide. Oxygen. Heat. Total. Increase. Total. Increase. Total. Increase. 1J to 3f hours grams. 70 67 64 61 grams. 25 22 19 16 grams. 56 58 54 57 grams. 16 18 14 17 cals. 197 197 188 172 cals. 55 55 46 30 3| to 5f hours. 5 j to 1\ hours. 7f to9J hours Total 262 82 225 65 754 186 Subject ate food in about 25 minutes. 316 FOOD INGESTION AND ENERGY TRANSFORMATIONS. calories for an 8-hour period, this increment of 186 calories shows a long and sustained increase, amounting to nearly 33 per cent of the basal metabolism. During the first two periods the increment was 55 calories above a basal value of 142 calories, or nearly 40 per cent increase. A. H. M., February 19, 1906. — The diet in this experiment consisted of 204 grams bananas, 63 grams potato chips, 29 grams potted chicken, 139 grams whole wheat breakfast food (dry), 103 grams graham bread, 284 grams oatmeal, 520 grams cream, 141 grams eggs, 150 grams peanut butter, a total of 1,633 grams. The fuel value of the food was 3,936 calories, of which 13 per cent came from protein, 54 per cent from fat, and 33 per cent from carbohydrates. As a result of the ingestion of this food, there was a large increase in the three factors of metabolism which continued throughout the experiment. (See table 241.) In the first two periods the increments in the heat production of 64 and 65 calories, respectively, correspond to an increase above basal of approximately 45 per cent. Even in the last period the increment in the heat was 41 calories. It can easily be seen from these results that a meal of this type taken in the morning would have an effect upon the metabolism for practically the entire working day. TABLE 241. — A. H. M., February 19, 1906. Sitting. (2-hour periods.) Heavy breakfast (mixed diet): Amount, 1,633 grams; nitrogen, 20.11 grams; total energy, 4,112 cals. Fuel value: Total, 3,936 cals.; from protein, 13 p. ct.; from fat, 54 p. ct. ; from carbohydrates, 33 p. ct. Nitrogen in urine, 1.72 grams per 2 hours. Basal values (February 12 and 14, 1906): CO2, 45 grams; Oz, 40 grams; heat, 142 cala. Time after food.1 Carbon dioxide. Oxygen. Heat. Total. Increase. Total Increase. Total. Increase. li to 3J hours grams. 73 68 66 62 grams. 28 23 21 17 grams. 66 53 55 56 grams. 26 13 15 16 cals. 206 207 201 183 cals. 64 65 59 41 3i to 5J hours 5$ to 7J hours 7i to 9i hours. Total 269 89 230 70 797 229 Subject ate food in 41 minutes. H. R. £>., February 17, 1906. — For breakfast this subject ate 77 grams dry cereal, 134 grams sugar, 381 grams cream, 123 grams apples, 658 grams milk, 205 grams baked beans, 31 grams bread, 29 grams peanut butter, 41 grams graham crackers, 146 grams eggs, and 3 grams potato chips, a total of 1,828 grams. This diet had a fuel value of 3,311 calories, of which 12 per cent came from protein, 43 per cent from fat, and 45 per cent from carbohydrates. The details of the experiment INGESTION OF MIXED DIETS. 317 are given in table 242. As a result of the ingestion of this food there was a marked increase in the three factors of metabolism which con- tinued throughout the experiment ; the increase in the heat production for the last period amounted to 33 calories. The total increase in heat production of 181 calories represents approximately a 32 per cent increment in this factor; similar percentage increments were noted for carbon-dioxide production and oxygen consumption. TABLE 242. — H. R. D., February 17, 1906. Sitting. (2-hour periods.) Heavy breakfast (mixed diet) : Amount, 1,828 grams; nitrogen, 14.64 grams; total energy, 3,439 cala. Fuel value: Total, 3,311 cals.; from protein, 12 p. ct.; from fat, 43 p. ct.; from carbohydrates. 45 p. ct. Nitrogen in urine, 1.25 grams per 2 hours. Basal values (February 6 and 10, 1906): CO2, 47 grams; O2, 42 grams; heat, 143 cals. Time after food.1 Carbon dioxide. Oxygen. Heat. Total. Increase. Total. Increase. Total. Increase. 1J to 3$ hours grams. 69 66 59 61 grams. 22 19 12 14 grams. 58 52 51 45 grams. 16 10 9 3 cals. 196 191 190 176 cals. 53 48 47 33 3J to 5J hours. 5i to 7$ hours 7J to 9J hours Total 255 67 206 38 753 181 1Subject ate food in 51 minutes. H. R. D., February 21, 1906. — The experiment on this date was prac- tically a duplicate of that with the same subject on February 17, as the diet had approximately the same fuel value. The proportions of energy from protein, fat, and carbohydrate were also approximately the same, although in this experiment a somewhat larger proportion of the energy was supplied by fat with correspondingly less from carbo- hydrates. The breakfast consisted of 81 grams graham crackers, 40 grams peanut butter, 26 grams cheese, 89 grams cereal, 56 grams sugar, 76 grams apples, 46 grams bread, 145 grams baked beans, 189 grams boiled eggs, 397 grams milk, and 634 grams cream, a total of 1,779 grams. The fuel value of the diet was 3,697 calories, of which 12 per cent came from protein, 54 per cent from fat, and 34 per cent from carbohydrates. The results of the experiment are given in table 243. Here again we find large increments in the metabolism throughout the experiment, with no evidence of a cessation at the end of the 8-hour experimental period. The total increase in heat produc- tion was not so large as in the experiment on February 17, being only 148 calories, or approximately 26 per cent of the basal value. The results show, however, like all of the experiments in this series, a pro- longed stimulus to the metabolism which continued for the entire 8 or 9 hours following the ingestion of the food. 318 FOOD INGESTION AND ENERGY TRANSFORMATIONS. TABLE 243.— H. R. D., February 21, 1906. Sitting. (2-hour periods.) Heavy breakfast (mixed diet): Amount, 1,779 grams; nitrogen, 17.09 grams; total energy, 3,845 cals. Fuel value: Total, 3,697 cals. ; from protein, 12 p. ct. ; from fat, 54 p. ct. ; from carbohydrates, 34 p. ct. Nitrogen in urine, 1.22 grams per 2 hours. Basal values (February 6 and 10, 1906) : CO2, 47 grams; Oj, 42 grams; heat, 143 cals. Time after food.1 Carbon dioxide. Oxygen. Heat. Total. Increase. Total. Increase. Total. Increase 1 1 to 3 f hours grams. 63 67 61 57 grams. 16 20 14 10 grams. 56 53 54 48 grams. 14 11 12 6 cals. 188 174 182 176 cot*. 45 31 39 33 3 J to 5J hours 5j to 7j hours. 7J to 9f hours Total 248 60 211 43 720 148 JSubject ate food in about 45 minutes. HEAVY SUPPER. Two experiments were made with the Middletown calorimeter in which excessive amounts of food were taken as a supper. Otherwise the experiments were similar in plan to the heavy-breakfast experi- ments, except that the measurements continued for a somewhat longer time and were not made in 2-hour periods. Both of the subjects had been used in the heavy-breakfast experiments. A. L. L., April 6-7, 1906. — The food taken consisted of 145 grams bread, 42 grams butter, 109 grams eggs, 57 grams potato chips, 256 grams bananas, 90 grams sweet chocolate, 446 grams milk, 103 grams cream, and 25 grams sugar, a total of 1,273 grams. The fuel value of the food was 2,364 calories, of which 10 per cent came from protein, 53 per cent from fat, and 37 per cent from carbohydrates. The food experiment continued from 9h15m p. m., April 6, tolh!5m p. m., April 7, in all, a period of 16 hours. The experiment was divided into three periods. In the first period of 9 hours from 9h15m p. m., April 6, to 6h15m a. m., April 7, the subject lay quiet and asleep for the greater part of the time. In the first hour and a half there was con- siderable activity, as he weighed himself, received and ate the food, returned the dishes used to the food aperture, and prepared for bed. During this period of activity he went to the food aperture 3 times and opened it about 15 times, and wiped up some spilled cream. He ate his supper between 9h40m p. m. and 10h34m p. m. and retired at 10h50m p. m. In the second period of one hour between 6h15m a. m. and 7h15m a. m., April 7, the subject rose, weighed himself, and dressed, then sat quiet (reading) for the remainder of the time. The third period INGESTION OF MIXED DIETS. 319 of 6 hours continued from 7h15m a. m. to Ih15m p. m.; the subject was quiet throughout the whole period. The basal values used for comparison were obtained on April 19 to 20, 1906, and on April 6, 1906. The lengths of the first and third periods of measurement do not correspond exactly to those of the food experiment, but the values have been computed to the same basis. The first fasting period contained less muscular activity than the corresponding food period, as the subject ate no food and retired 12 minutes after the beginning of the period. An examination of the results given in table 244 shows that the heat production in the 16 hours of the food experiment increased 281 calories over that in 16 hours of fasting, representing a percentage increment of approximately 25 per cent. Furthermore, in the last 6 hours of the experiment there was a metabolism measurably above that of the control period, showing a prolonged after-effect of the food ingestion. TABLE 244.— A. L. L., April 6-7, 1906. Heavy supper (mixed diet): Amount, 1,273 grams; nitrogen, 8.87 grams; total energy, 2,442 cals. Fuel value: Total, 2,364 cals.; from protein, 10 p. ct.; from fat, 53 p. ct.; from carbohydrates, 37 p. ct. Date. Body position. Period. Nitrogen in urine. Carbon dioxide. Oxy- gen. Heat. 1906. Without food : Apr. 19-20 Lying1 . . Q'KXFp.m. to 7hOOma.m. . gms. 21.66 gms. 2201 gms. 2173 cals. 2590 Apr. 20 Rising, weigh- Apr 6 ing, sitting.. Sitting 7 00 a.m. to 8 00 a.m. . 1 15 p.m. to 9 15 p.m.. .23 31.07 32 3135 27 3126 92 S426 Total (16 hours).. 368 326 1,108 With food : Apr. 6-7 Lying1 . 9h15mp.m. to 6b15ma.m.4 3.27 271 245 792 Apr. 7 .... Rising, weigh- Apr 7 ing, sitting.. Sitting 6 15 a.m. to 7 15 a.m. . 7 15 a.m. to 1 15 p.m.. .46 2.23 37 152 28 138 116 481 Total (16 hours).. Increase 460 92 411 85 1,389 281 Subject retired at 9h12m p. m. on night of April 19-20 and at lO^O01 p. m. on April 6-7. Pre- vious to these times there was the activity connected with weighing and the preparations for retiring; on the night of April 6-7 subject went to the food aperture 3 times and opened it about 15 times. 2Computed to basis of 9 hours, i. e., to the duration of corresponding period with food. 'Computed to basis of 6 hours. 4Subject finished eating about 1$ hours after the beginning of this period. H. R. D., April 10-11, 1906.— The food taken in this experiment was 37 grams dry cereal, 111 grams sweet chocolate, 95 grams peanut butter, 233 grams baked beans, 76 grams apples, 307 grams milk, 409 grams cream, 67 grams whole- wheat bread, and 229 grams boiled 320 FOOD INGESTION AND ENERGY TRANSFORMATIONS. eggs, a total of 1,564 grams. The fuel value of this diet was 3,442 calories, of which 13 per cent came from protein, 63 per cent from fat, and 24 per cent from carbohydrates. The measurements were made in one period of 10? hours and one period of 10 hours. (See table 245.) The average basal value used for the first food period was drawn from measurements made on three different days with reasonably concord- ant values. Although the periods of measurement differed slightly from those of the food experiment, the basal values have been computed to a comparable basis. TABLE 245.— H. R. D., April 10-11, 1906. Heavy Cupper (mixed diet): Amount, 1,564 grams; nitrogen, 17.81 grams; total energy, 3,599 cals. Fuel value: Total, 3,442 cals. ; from protein, 13 p. ct.; from fat, 63 p. ct. ; from carbohydrates, 24 p. ct. Date. Body position. Period. Nitrogen in urine. Carbon dioxide. Oxygen. Heat. 1906. Without food : Apr. 20-21.. May 9-10.. May 17-18. . Lying1. . . Lying1. . . Lying1 . . . 9hOOmp.m. to 7hOOma.m 9 30 p.m. to 7 30 a.m 9 10 p.m. to 7 10 a.m grams. 24.95 25.82 27.68 grams. 2226 2218 2224 grams. 2208 2188 2187 cals. 2694 J648 2666 Average 6.15 223 194 3669 Apr. 10 Sitting . . . Ih00mp.m. to 9hOOmp.m 43.50 4240 4210 4755 Total (20J hours). 463 404 1,424 With food: Apr. 10-11. . Apr. 11 Lying1 . . . Sitting . . . 9hOOmp.m. to 7h15ma.m.B. . . 8 15 a.m.6 to 6 15 p.m 6.85 5.26 325 264 293 232 921 837 Total (20J hours).. . 589 525 1,758 Increase 126 121 334 Subject retired at 9h16m p. m. on night of April 20-21, at 9h42m p. m. on May 9-10, at p. m. on May 17-18, and at 10h26m p. m. on April 10-11. Previous to these times there was the activity connected with weighing and the preparation for retiring; on the night of April 10-11 subject went to the food aperture twice and opened it 20 times. 2Computed to basis of 101 hours, i. e., to duration of corresponding period with food. 3Heat values on nights of April 20-21 and May 17-18 not corrected for small change in body- weight or for change in body-temperature. 'Computed to basis of 10 hours. 5Subject finished eating about an hour after the beginning of this period. •Period, 7h15m a. m. to 8b15m a. m., when subject rose, weighed, etc., is omitted because satis- factory base-line was not obtained. As in the previous experiment, the activity in the first food period was somewhat greater than that in the fasting periods with which it was compared, for the subject retired earlier in the fasting experiments and the activity due to receiving and eating food was absent. He went to bed on April 20 at 9h16m p. m., on May 9 at 9h42m p. m., and on May 17 at 9h30m p. m. On April 10-11 (the food period) he ate supper between 9h20m p. m. and 10h08m p. m., finishing about an hour after the beginning of the experiment. During this time he went to the food aperture twice and opened and shut it 20 times. He retired at 10h26m p. m. As no suitable basal value could be obtained for com- INGESTION OF MIXED DIETS. 321 parison, the active period in the morning from 7h15m a. m. to 8h15m a. m. has been omitted from the table. As a result of eating this heavy supper a considerable increment was found for all of the factors of metabolism. That for heat production during the total period of 20 j hours was 334 calories, this correspond- ing to a percentage increment of approximately 23 per cent. A com- parison of the two sitting periods shows a prolonged after-effect of the heavy meal on the morning following its ingestion. RESPIRATION EXPERIMENTS. In the calorimeter experiments no attempt was made to apportion the increment from period to period and study the time relations to find if there were a "peak" effect. This was possible only with short- period experiments, such as could be made with a respiration apparatus. Unfortunately but two experiments with mixed diet were made with such an apparatus. In both of these experiments the basal value was determined in several periods just preceding the ingestion of the food. J. J. C., February 28, 1911. — The universal respiration apparatus was used for this experiment of 12 periods (3 periods of fasting and 9 periods after food). The diet consisted of 210 grams black bread, 15 grams sugar, 25 grams butter, and 500 grams coffee, or a total amount of 750 grams. The fuel value of the diet was 796 calories, of which 11 per cent came from protein, 26 per cent from fat, and 63 per cent from carbohydrates. The results of the experiment are given in table 246. In about 1| hours after the taking of the food, the heat production had increased from 1.16 calories to a maximum of 1.43 TABLE 246. — J. J. C., February 28, 1911. Lying. (Values per minute.) Mixed diet: Amount, 750 grams;1 nitrogen, 3.42 grams; total energy, 826 cals. Fuel value: Total, 796 cals.; from protein, lip. ct.; from fat, 26 p. ct.; from carbo- hydrates, 63 p. ct. Time. Average respiration rate. Carbon dioxide. Respira- tory quotient. Oxygen. Average pulse rate. Heat (com- puted). Without food : c.c. c.c. cals. Av. of 3 periods 16 198 0.83 239 69 1.16 With food:2 Ilh05ma.m 16 210 73 1.18 11 41 a.m 16 248 .90 275 69 1.35 12 14 p.m 17 257 .88 291 72 1.43 12 44 p.m. . . . 17 246 .87 284 73 1.39 1 17 p.m 18 251 .92 274 72 1.36 1 48 p.m 16 248 .95 262 72 1.31 2 23 p.m 16 243 68 1.33 2 59 p.m 15 221 .84 264 66 1.28 3 31 p.m 15 214 .87 246 64 1.20 Includes 500 grams coffee. 2Subject ate between and 10h54m a. m. 322 FOOD INGESTION AND ENERGY TRANSFORMATIONS. calories per minute. At the end of the experiment, nearly 5 hours after the ingestion of food, the heat production had not quite reached the basal value. A. F., April 20, 1915. — The second respiration experiment with a mixed diet was made with the Tissot respiration apparatus. The food included 45 grams egg (boiled), 250 grams milk, 37 grams toast, and 12 grams butter, a total of 344 grams. The fuel value of the diet was 468 calories, of which 17 per cent came from protein, 52 per cent from fat, and 31 per cent from carbohydrate. The details of the experiment are given in table 247. The heat production increased from a basal value of 1.27 calories per minute to a maximum of 1.45 calories per minute in approximately 30 minutes after the taking of the food. This was followed by a gradual decrease, but at the end of the experiments nearly 3 \ hours after the food had been taken, the basal value had not, been reached. TABLE 247. — A. F., April 20, 1915. Lying. (Values per minute.) Mixed diet: Amount, 344 grams; nitrogen, 3.04 grams; total energy, 494 cals. Fuel value: Total, 468 cals.; from protein, 17 p. ct.; from fat, 52 p. ct. ; from carbohydrates, 31 p. ct. Time. Ventila- tion (reduced) . Average respiration rate. Carbon dioxide. Respira- tory quotient. Oxygen. Average pulse rate. Heat. Without food : liters. c.c. c.c. cals. Av. of 2 periods . . 8.12 31.3 210 0.79 265 70 1.27 With food r1 9h58ma.m 9.09 34.9 240 .80 301 1.45 10 16 a.m 9.15 35.2 235 .81 292 67 1.41 11 27 a.m.2. 9.33 37.0 231 .81 286 62 1.38 11 48 a.m 6 53 17.1 217 .80 270 60 1.30 12 46 p.m.2 6.33 16.6 216 .79 275 58 1.32 'Subject ate between 9h23m and 9h29m a. m. ^Subject sat up between 10h28m and 10h58m a. m. and between 12h and 12h25m p. m. It is evident that these two respiration experiments throw but little light upon the general course of the metabolism after the taking of a mixed diet. The calorimeter experiments, especially those following an excessive amount of food, showed a pronounced effect upon the metabolism. It is much to be regretted that the experimental pro- cedure of the studies with the calorimeter did not permit the caretul separation of the results into short periods, so that we might gain some information as to the exact course of the metabolism, the time relations, and the altitude of the peak effect. While we are able to study more closely these particular points in the short-period respiration experi- ments with carbohydrate and protein diets, the evidence supplied with mixed diets is slight, suggesting only that the peak effect probably occurred soon after the ingestion of the food. INGESTION OF MIXED DIETS. 323 PREVIOUSLY PUBLISHED EXPERIMENTS WITH MIXED DIETS. In an earlier publication on fasting,1 four food experiments with mixed diets were reported following fasts of 4 to 7 days in duration. These have already been discussed in our consideration of the basal metabolism (see pages 55 to 60), but are abstracted here, as they give further information regarding the influence of a mixed diet. As stated in the previous discussion, our earlier plan was to use fasting values as base-lines, and then note the increment in the metabolism due to subse- quent food ingestion. When we attempted to select a base-line, a number of serious objections to this at once presented themselves. In the first place it was noted that the total metabolism for the day almost invariably decreased gradually as the fast progressed. An examina- tion of the data in table 248, which presents in abstract the four food experiments referred to, together with the preceding fasting periods, shows that in practically every instance there was a tendency for the heat production to decrease as the fasting continued. This tendency is most clearly shown in the fasting periods with S. A. B. on January 8 TABLE 248. — Heat production of A. L. L. and S. A. B. without food and after the ingestion of a mixed diet. [Values per 24-hours (7 a. m. to 7 a. m.)] Subject and date. Experimental day and fuel value of food. Heat. Subject and date. Experimental day and fuel value of food. Heat. A. L. L.- 1904. Dec 16-17 Fast. First cals. 1,951 S. A. B.3 1905. Jan. 8-9 ... Fast. Second4 cals. 1,844 Dec 17-18 Second 2,163 Jan. 9-10 Third 1 746 Dec 18-19 Third 2,035 Jan. 10-11 Fourth 1 606 Dec 19-20 Fourth 1,958 Food. Food. (2,502 cals.) Jan. 11-12 (1,698 cals.) First 1,677 Dec. 20-21 First 2,104 Dec. 21-22 Second 2,223 Dec. 22-23 Third 2,457 S. A. B.5 1905. Jan. 28-29 . ... Fast. First cals. 1,866 S. A. B.6 1905. Mar. 4— 5 Fast. First cals. 1,765 Jan. 29-30 Second . . . 1,791 Mar. 5— 6 Second .... 1,768 Jan. 30-31 . Third 1,739 Mar. 6- 7 Third 1,797 Jan. 31-Feb. 1 Fourth . . 1,663 Mar. 7- 8 Fourth 1,775 Feb. 1-2 .... Fifth 1,548 Mar. 8- 9 Fifth 1,649 Food. Mar. 9-10 Sixth 1,553 (2,078 cals.) Mar. 10-11. . . Seventh 1,568 Feb. 2-3 First 1,691 Food. Feb. 3-4 Second 1,585 (1,788 cals.) Feb. 4-5 Third 1,607 Mar. 11-12 First 1,767 Mar 12-13 Second 1,728 Mar 13-14 Third 1,754 'Benedict, Carnegie Inst. Wash. Pub. No. 77, 1907. 2See table 7, p. 56. 3See table 8, p. 57. 4First day not included because of work done on bicycle ergometer. 5See table 9, p. 58. "See table 10, p. 59. 324 FOOD INGESTION AND ENERGY TRANSFORMATIONS. to 11, 1905, and January 28 to February 2, 1905. It so happens that in the long fasting experiment of 7 days with S. A. B., the metabolism was essentially constant on the first 4 days ; on the fifth day there was a sudden fall of over 100 calories, followed by another fall of 100 calories on the sixth day. In the experiment with A. L. L., the varia- tions in the metabolism are somewhat pronounced ; as a matter of fact the value is the same on the fourth day as on the first. Certain varia- tions in these values from day to day may be in part accounted for by variations in muscular activity, although the attempt was made to have like activity on all days. In the food experiment with A. L. L., the diet averaged 1,615 grams of a modified milk and 6 grams of plasmon per day, the total daily intake being 1 ,621 grams. This had a total fuel value of 2,502 calories, of which 9 per cent came from protein, 79 per cent from fat, and 12 per cent from carbohydrates. In the food experiment with S. A. B., January 11 to 12, 1905, the food taken per day was 1,253 grams of a modified milk and 106 grams of orange juice, the daily amount being 1,359 grams. The total fuel value was 1,698 calories, of which 9 per cent came from protein, 73 per cent from fat, and 18 per cent from carbohydrates. In the second food experiment with S. A. B. (February 2-5, 1905), the subject ate per day, 1,200 grams modified milk, 123 grams apples, 313 grams orange juice, and 35 grams graham crackers; the daily total was 1,671 grams. The total fuel value was 2,078 calo- ries, of which 8 per cent came from protein, 65 per cent from fat, and 27 per cent from carbohydrates. In the last food experiment with S. A. B. (March 11-14, 1905), the food taken per day was 650 grams modified milk, 123 grams apples, 178 grams whole wheat breakfast food (dry), 10 grams gluten bread, and 313 grams orange juice, a daily total of 1,274 grams. The total fuel value was 1 ,788 calories, of which 9 per cent came from protein, 37 per cent from fat, and 54 per cent from carbohydrates. The amounts of food ingested were unfortunately not satisfactory, the fuel value of the food intake being determined solely by the appe- tite of the subject on the first day of food following the fast. The diet for the subsequent days was the same as that on the first day, the amounts varying only a few grams, if at all. The fuel value of the food in the experiment with A. L. L. was considerably above the 24-hour maintenance requirement. In the first experiment with S. A. B., it was essentially that of maintenance, in the second experiment with this subject it was measurably above maintenance, and in the third experi- ment it was above the maintenance requirements during the fasting, but practically the same as the need for maintenance during the food period. We thus consider here an influence of food upon the fasting metabo- lism which is not represented simply by the increment above a basal INGESTION OF MIXED DIETS. 325 value obtained by averaging all of the fasting days, as the basal value may change and in certain circumstances does change considerably during the fast. This was shown clearly in the fasting experiment of 31 days carried out in the Nutrition Laboratory.1 It hardly seems justifiable to attempt a computation of the fasting values obtained in these four experiments on the basis of per kilogram of body-weight or per square meter of body-surface. There were, to be sure, measurable losses in weight which were probably largely due to a loss of water from the body, especially in the earlier part of the fast. That there was a considerable loss in body-surface or of active heat- producing organized tissue is hardly conceivable. After the ingestion of food there were undoubtedly slight gains and losses in weight, but this discussion considers the organism as a whole, for only days with and without food are compared and no attempt is made to compare results obtained with different individuals. Even in the first experiment recorded in table 248 (that with A. L. L.) the actual value of the base-line may be seriously questioned. An average value for the fasting periods would be not far from 2,025 calo- ries. On this basis it can be seen that the ingestion of food, with a fuel value of 2,502 calories, barely increases the metabolism on the first day, increases it noticeably on the second, and produces a very pronounced increase on the third. In the first experiment with S. A.B., the ingestion of food, with a fuel value essentially that of maintenance during fasting, resulted in a slight increase in the metabolism on the first food day over the metab- olism on the fourth fasting day. If, however, the average of the fasting days is taken as an absolute value, it will be seen that the ingestion of food simply checked the progressive decrease in the metabolism. Here again the uncertainty of the base-line is noticeable. In the second experiment with S. A. B., the ingestion of food with a fuel value considerably above the 24-hour maintenance requirement (over 500 calories above the final fasting-level) resulted in an increase in heat production of a little over 100 calories, while in the last experiment with S. A. B. the ingestion of food with a fuel value about 200 calories higher than the heat production on the sixth and seventh fasting days resulted in an increase in the metabolism of approximately 200 calories, the daily metabolism on the food days being almost exactly equal to the fuel value of the intake.2 From this varied picture of the influence of food ingestion upon metabolism following fasting, certain rather clear conclusions may be drawn. First, in all instances food produced an increased metabolism 'Benedict, Carnegie Inst. Wash. Pub. No. 203, 1915, p. 372. 2Grafe (Deutsch. Arch. f. klin. Med., 1913-14, 113, p. 1), comparing results obtained in a prolonged fast with those obtained with a diet of almost pure carbohydrates, found no rise in the metabolism after food. 326 FOOD INGESTION AND ENERGY TRANSFORMATIONS. over the last fasting day. This increase was independent of whether the fuel value of the food was considerably above or below that required for maintenance on the fasting day. Second, with the same individual the reaction to food was apparently by no means constant, for in the first two experiments with S. A. B. there was little, if any, increment due to food, although in the second experiment the fuel value of the food was from 400 to 500 calories above fasting maintenance requirements. On the contrary, at the end of the 7-day fast, food with a fuel value of 200 calories greater than the heat production of the last fasting day produced an increase of 200 calories in the total heat production. In all probability the length of the fast, the influence upon the basal metab- olism of the fasting per se, the fuel value of the intake, and the propor- tion of protein in the intake are in some way related. In all of the experiments reported in this table there was an actual loss of nitrogen during the food experiment, as there was not sufficient protein in the intake to compensate for the outgo. Finally, although the evidence is somewhat meager, it is of funda- mental importance to consider the relationship between the ingestion of food and the basal metabolism after fasting, with a view to consider- ing the possibilities of lowering the basal metabolism by inanition or undernutrition, and then maintaining the metabolic level on smaller food requirements than those ordinarily obtaining. For example, in the first experiment with S. A. B., we have a heat production on the second fasting day of 1,844 calories. On the fourth day this was reduced to 1,606 calories. The fuel value of the food ingested was 1,698 calories, which was essentially that required for maintenance. It is quite clear, therefore, that we deal here with a maintenance, at least temporarily obtaining, at a level of 150 or more calories below that on the second fasting day. The fact that in the second experiment with S. A. B. the 2,078 calories in the food did not cause a pronounced rise in the metabolism is likewise of great significance, for by 5 days of fasting the basal metabolism was lowered over 300 calories, and the ingestion of an excess amount of food over requirements on the next 3 days increased the heat production only about 100 calories above the last fasting day. On the other hand, these conclusions are considerably weakened by the course of the metabolism in the last experiment with S. A. B., in which food with a fuel value a little above the fasting requirements produced an increment of 200 calories, raising the metab- olism to that on the first three or four fasting days. These experiments are extremely suggestive in their bearing on the question of a basal metabolism lowered either by fasting or by prolonged undernutrition. They should be followed by observations on the influence of very moderate or barely maintenance diets to note if the tendency of the basal metabolism is to return to the initial value or to maintain the lowered value found as a result of undernutrition or INGESTION OF MIXED DIETS. 327 inanition. The reported experience of Germany and Austria at the time of writing would seem to indicate that observations of this kind are unwittingly being made there, but unfortunately it is probable that these are without a scientific measurement of the basal metabolism.1 The statistical and superficial evidence indicates that certain classes of the Teutonic nations are subsisting on very low diets, so far as the calorie intake is concerned. While definite information is lacking as to their capacity to perform physical work on this low diet, the evidence of scientists who have visited Europe is somewhat conclusive in leading to the belief that there has been no proportionate loss in physical prowess or ability to perform work by this reduction in basal require- ments. It is evident that this should be made the subject of most careful physiological research,2 as apparently during fasting the organ- ism becomes accustomed to existing upon a perceptibly lower level. There is naturally a loss of weight which is, it is true, in some small part made up of organized protoplasmic tissue and in large part of water and fatty tissue, but it is hardly conceivable that the heat-producing organism as such is proportionately reduced in capacity or size by the fasting. It is probable, however, that the stimulus to cellular activity is considerably lowered as a specific result of the fasting process. To what extent this stimulus is regenerated by moderate amounts of food, and how much the total metabolism may be influenced by the intro- duction of foreign protein, even under conditions when there is a draft upon body protein, are at present unsolved problems which should be carefully studied. lSince writing the above we have been able to secure a copy of an article by Loewy and Zuntz (Berlin, klin. Wochenschr., 1916, 53, p. 825) and find that studies of the basal metabo- lism of both authors have been made with all the accuracy and painstaking care characteristic of Professor Zuntz's work. A pronounced decrease in basal metabolism as a result of the en- forced reduction in diet is noted in both cases. 2Such a research has but recently (February 3, 1918) been completed by the Nutrition Laboratory and the data are now being elaborated for publication. 328 FOOD INGESTION AND ENERGY TRANSFORMATIONS. SOME RELATIONSHIPS BETWEEN ENERGY OUTPUT AND FOOD INTAKE. The evidence presented in the foregoing chapters of this book deals principally with the energy transformations incidental to the ingestion of food. The experimental plan, while undergoing many changes in the decade in which the research has been in progress, nevertheless had, as its fundamental basis, a quantitative measurement of the energy transformations, either directly by means of the calorimeter or indirectly by calculation from data obtained for the respiratory exchange; in many of the experiments the nitrogen excretion was also determined. In sev- eral series of experiments a measurement was made of the increase in the energy output required for the mastication of food or the drinking of such liquids as water, coffee, and beef tea, but aside from the experi- ments in which the effect of mastication was studied, and a few calo- rimeter experiments in which the food materials were taken within the experimental period, the work of prehension and the external muscular work of eating were entirely excluded. When possible, pure nutrients were used; if this was not practicable, as was only too frequently the case, a diet was employed in which a special nutrient predominated ; thus a study could be made of the quan- titative transformations following the ingestion of various kinds of food. It has been our plan to discuss in the foregoing chapters the experiments of each division of the research and thus in a way subse- quent discussion is more or less of a repetition. It is perfectly legiti- mate, however, to recapitulate and attempt to correlate the findings for the several classes of food materials. The only purely mechanical process studied was that of chewing. Although unfortunately the evidence is not definite in every case, never- theless the general picture is sufficiently clear to state positively that mastication produces a distinct increase in the heat production. It has likewise been pointed out that, though contrary to the belief of some enthusiasts who advocate prolonged mastication for the more perfect digestion and assimilation of food material, the unused portion of mod- ern food materials is, under normal conditions, extraordinarily small. The preliminary preparation of practically all of the food materials of civilized man removes in large part the indigestible portion ; the energy content of almost any mixed diet may therefore be said to be absorbed to the extent of 90 per cent or over. Since pure carbohydrates are almost perfectly absorbed, it is probably safe to assume that with ordi- nary mixed diet approximately 95 per cent of the energy is actually absorbed. The error in computing unabsorbed material from an analysis of the feces should again be emphasized. Fecal matter by no means consists wholly of undigested food material, but is made up in large part of ENERGY RELATIONSHIPS. 329 bacteria, the residue of digestive juices, and the debris of the epithelial lining of the intestinal tract. It is the common custom to analyze fecal material and to consider the nitrogen obtained as a measure of the unabsorbed protein, the fat as unabsorbed fat, and the carbohydrate, although existing in small amounts, as unabsorbed carbohydrates. This is fundamentally wrong, although the method for determining the digestibility of food has been based upon these false premises practi- cally ever since the introduction of food analysis. It can be seen that an absorption of 95 per cent on this basis would, when properly inter- preted, mean an actual energy absorption of nearly 98 per cent; hence the advocates of excessive mastication must attempt to increase an absorption which is already 98 per cent of the total amount. This is obviously impossible and physiologically unsound. If we further con- sider the extra energy required for excessive mastication, it is more than probable that such slight increase in absorption as may possibly occur with an excessive comminution of food materials by prolonged chewing may be considerably more than offset by the additional con- sumption of energy required for mastication. In the experiments on drinking liquids, such as water which is with- out nutritive qualities, beef tea which has a measurable amount of the stimulating extractives (creatine and allied compounds), and coffee which contains a slight amount of extractives and of caffein (a heart stimulant), the picture is again not uniformly clear. Sufficient experi- mental evidence has been accumulated, however, to state positively that the drinking of large amounts of water results in an actual increase in the total production. Beef tea, taken either hot or cold, likewise slightly increases the metabolism. Coffee produces a similar slight increment. While a logical explanation of the increase in metabolism due to coffee and beef tea might be found in their content of stimulating materials, such as caffein and creatine, it is difficult to explain the increase due to water on this basis, and it is not impossible, even in the absence of positive evidence, that we have to deal here with an internal mechanical process which may be directly associated with the secre- tion of the normally occurring large amounts of urine following exces- sive liquid ingestion. In a final consideration of the results of drinking liquids which show, as a rule, a relatively small increase in metabolism due to this factor, we must again state that the experimental technique was by no means perfect at that period of the research, and that the defects in the base- line frequently vitiated many of the results. As was clearly brought out in the discussion of the basal metabolism, such variations have considerable significance when the basal values are used for compar- ison with values obtained in subsequent periods in which only small increments are found; it is thus especially important to secure accu- rate basal values for such experiments. Accordingly, in studying the 330 FOOD INGESTION AND ENERGY TRANSFORMATIONS. results of the group of experiments under consideration, it is neces- sary to draw conclusions not from the detailed results, which were based in some cases upon defective values, but from the general picture pre- sented. This general picture shows that the ingestion of a large amount of liquid, such as water, coffee, or beef tea, is followed by a measurable increase in the metabolism. Following the ingestion of food materials a pronounced increment in the metabolism was almost invariably found. We may therefore dis- regard possible inaccuracies in the base-line and discuss the experiments on the general assumption that the basal values were determined with sufficient accuracy to warrant quantitative deductions from the incre- ments actually measured, although we freely admit that whenever practicable a carefully determined base-line each day prior to the inges- tion of food is highly desirable, if not, indeed, absolutely essential. The observed increment in the metabolism as a result of the ingestion of food is in accordance with the experience of nearly all of the other investigators in this field. The increase was especially pronounced with protein, carbohydrates, and mixed diets, and less pronounced when diets with a preponderance of fat were used. GENERAL QUANTITATIVE RELATIONS. The fact that different amounts of the several foodstuffs produce varying increases in metabolism would make it appear that the estab- lishment of definite mathematical relationships between the amounts of food ingested, the character of the food ingested, and the increments would be relatively simple. This, however, on close analysis, proves to be far from the case. To establish a quantitative relationship between the various foods ingested and the increase in the basal metabolism it is necessary to note first the length of the experimental period to be considered. If the total increment due to the ingestion of food is desired, the period of measurement must be extended until the increment due to the ingestion of food has disappeared and the metabolism has again reached the basal level. For instance, if the basal heat production is 70 calories per hour and the metabolism increases after the ingestion of food to 100 calories per hour for one or two hours, obviously no complete mathematical relationship can be established unless the measurements are continued until the basal value of 70 calories per hour is again obtained. This is somewhat difficult, especially when the stimulus effect is prolonged, as it is with protein. The first quantitative relationship to be considered is the increment in the metabolism above the basal level, to find how far it is possible to increase the basal metabolism by the ingestion of nutrients. This is in reality a measurement of the absolute maximum increment due to the ingestion of food, somewhat similar to the "peak " effect in the load of a ENERGY RELATIONSHIPS. 331 power plant, and has considerable interest as an index of the possible maximum influence of food. With carbohydrates the basal metabo- lism may be increased to an average maximum of approximately 25 per cent by the ingestion of 100 grams of any one of several sugars. This increment occurs inside of two hours and the metabolism has a tend- ency to return to the base-line somewhat rapidly thereafter. For a detailed discussion of the differences in effect of various forms of sugars, the section on carbohydrates should be consulted. (See page 171.) Of special significance is the fact that the increment with levulose over that with either sucrose or dextrose, which was earlier reported from this laboratory,1 is not noted when the results of all the experiments are combined, and we find that there is a greater similarity between levulose and dextrose than was at first believed. It will be seen, from table 173, that the levulose has a more pronounced effect upon carbon- dioxide production than the dextrose has, although not so great as that of sucrose. When the comparison is made on the basis of the heat pro- duction, it is found that the difference between dextrose and levulose in large part disappears, although sucrose still shows a higher value. Most of the pure sugars were studied with both 75-gram and 100- gram portions. While no uniform variation was noted in the effect upon the metabolism, it was usually found that the increment with the larger amount was greater than with the smaller amount, although the differences were by no means proportional. With protein the large increments in metabolism found by all work- ers were also noted in this research. The heat production increased usually to a maximum above the basal level of approximately 25 per cent, with a possible maximum of 45 per cent. (See tables 215 and 230.) The increment persisted for a long time, often from 8 to 12 hours. Indeed, our experiments were defective in that the experimental periods were in general not sufficiently extended to obtain the entire effect due to the protein ingestion. This prolonged increment is in striking con- trast to the increments obtained with carbohydrates, which, while fairly high (25 per cent) , nevertheless fell rapidly to a basal value after a rel- atively few hours. The experiments with fat are of special interest, though unfortunately the most liable to criticism on the grounds of experimental error and faulty technique. The inherent difficulties in feeding American sub- jects large quantities of pure oil or pure fat made it impossible for us to carry out any experiments with pure oil, as did Gigon, and we were obliged to confine ourselves to experiments with cream and with butter and potato chips. In practically all of the combinations used, a cer- tain amount of other nutrients was inevitably included, which some- what complicated the deductions drawn from the experiments. The 'Benedict, Trans. 15th Int. Cong. Hygiene and Demography, Washington, 1913, 2 (2), p. 394. 332 FOOD INGESTION AND ENERGY TRANSFORMATIONS. evidence is, however, sufficiently extensive and the general trend is such as to justify the conclusion that the ingestion of a diet containing a pre- ponderance of fat has a distinct effect upon the metabolism, although this was much less than that found with either protein or carbohydrate. The findings are so irregular that it is probably unjustifiable to use the single highest maximum value found, and we must therefore resort to the average figure, which is not far from a maximum of 12 per cent. In the experiments with mixed diets, in which frequently the subject took a sufficient number of calories in one meal to provide maintenance for a man at severe muscular work the entire day, i. e., approximately 4,000 calories, the maximum increment reached 40 per cent or more. An absolute accuracy of ± 3 per cent in the measurement of the basal metabolism on any given day is hardly obtainable. Furthermore, variations in the body position have an effect upon the basal metabo- lism. It has been shown that the basal value obtained with the subject lying quietly without food in the stomach may be increased slightly by having the subject sit upright in a chair.1 On the other hand, Du Bois2 finds that with the subject sitting properly supported in a steamer chair, the basal metabolism is not increased over that found with the subject in the lying position and in certain instances it was even de- creased. Standing upright has been found to increase the metabolism approximately 10 per cent.3 The maximum effects obtained with carbohydrates, protein, and mixed diets are, however, very considerably greater than those due to ordinary changes of position. While one might state tentatively that the increments with food, at least at the height of digestion, are such as would be expected when man is performing light muscular work, the inadequate definition of the term " light muscular work" is such as to make this of little significance. Too little knowledge is available at present regarding the increments in metabolism accompanying simple, every-day customs; hence we find ourselves at a loss to compare the increments for these food materials with those accompanying minor muscular activity. The increments with food are certainly much less than those obtained as a result of walking. On the other hand, since there is an increase in both the respiration and the circulation, it is evident that the ingestion of food and its effect upon metabolism are to be considered much more broadly than as an increment in the gaseous metabolism. There is unquestionably a stimulation in the muscular activity and general muscular tonus, accompanied by a sense of increased vigor, which is wholly out of proportion to the relatively small increase in the metab- and Riche, Am. Journ. Physiol., 1911, 27, p. 406. 'Soderstrom, Meyer, and E. F. Du Bois, Arch. Intern. Med., 1916, 17, p. 872. 'Benedict and Murschhauser, Carnegie Inst. Wash. Pub. No. 231, 1915. Benedict and Car- penter, Carnegie lust. Wash. Pub. No. 120, 1910. ENERGY RELATIONSHIPS. 333 olism. The increments are, however, sufficiently large to preclude any attempt to measure the basal metabolism during the active stages of digestion. Experimenters have therefore for years wisely insisted upon the post-absorptive condition, that is, 12 hours after the last meal. This is particularly necessary when the preceding diet has contained liberal quantities of protein or an excessive amount of a mixed diet. Our observations, in common with those of many others, show very clearly that the effect of the ingestion of pure carbohydrate or of fat is with normal individuals concluded in a relatively few hours ; were it not for the protein in the diet, therefore, one might state that the post- absorptive condition, or the so-called nuchtern condition, could be obtained in a much shorter period than 12 hours. Insistence on the 12-hour period is, in all events, the wiser course. Even with this inter- val, the injunction should be given to all subjects that excessive pro- tein should not be taken in the last meal prior to the experimental period. (See page 286.) RELATIONSHIP OF THE FUEL VALUE OF INGESTED FOOD TO EXCESS HEAT PRODUCTION. A relationship of unusual interest is that of the increase in the heat production following the ingestion of food to that of the fuel value of the food taken. While it may seem at first sight a gross misuse of engineer- ing terms or terms of efficiency to apply them to the apportionment of the caloric value of the ingested food of man, one might consider from an engineering standpoint or from that of industrial efficiency that the ingestion of food containing a certain number of calories would result in a certain amount of excess heat. Excess heat production represents an expenditure, either necessitated by the ingestion of food or resulting from the ingestion of food, and hence may logically be attributed to and in a sense chargeable to it. In considering the metabolism subsequent to the ingestion of food, one should bear in mind the following facts: A considerable portion of the diet, at least with ruminants, is distinctly indigestible, this portion consisting of woody fiber, cellulose, etc. Secondly, only part of the protein of the diet is oxidized inside the body. This is true of all ani- mal life, the unoxidized portion of the protein molecule being with mammals excreted chiefly in the form of urea. Furthermore, and this applies more particularly to ruminants, fermentation processes take place in the large intestine and cause a considerable production of marsh gas and a liberation of heat as the result of bacterial action. Finally, the ingestion of food per se causes an increase in the heat pro- duction. It is clear, therefore, that a measure of the heat of combus- tion of the intake has but little significance in relation to the ultimate 334 FOOD INGESTION AND ENERGY TRANSFORMATIONS. disposition of the total calories ingested or to the amount available or useful to the body. Writers and experimenters in animal physiology, particularly in animal nutrition, have considered the energy of intake under various heads, and attempted its apportionment in some measure to the several processes of digestion and absorption. It has long been assumed that an increment in the heat production which is not directly available for muscular work is of little, if any, value to the animal economy. Writers have therefore been inclined to consider more especially that portion of the food intake which participates in the heat produced inside the body by muscular and glandular activity in distinction from the food taking part in the production of heat in fermentative activities. Such attempts to separate the various subdivisions of the energy consump- tion produce great confusion. Perhaps no one has given this phase of the matter more comprehensive treatment than Armsby in his admirable treatise.1 He considers as metabolizable energy that frac- tion of the energy of the food which can enter into the metabolism of energy in the body, without differentiating as to the use made by the body of the energy thus metabolized. As the food of man contains but little unoxidizable material, like cellulose or fiber, the human diet may be considered as practically all digestible with the exception of the nitro- genous portion of the protein molecule which is excreted unoxidized in the form of urea. This material is still capable of being converted into heat, for each gram of urea has an energy value of 2.528 calories.2 In computing the caloric value of the food intake, therefore, due allow- ance must be made for the unoxidizable material in the protein. A consideration of the heat production of the human body deals chiefly with the disposition of the energy liberated after the food is absorbed. For convenience, we may consider that the ingestion of a definite amount of food produces an increase in the metabolism which may be chargeable to the food itself. If this is expressed in terms of calories, the total caloric value of the intake of food may properly be compared with that of the excess heat production. In this publication we have used for this purpose not the heat of combustion of the diet, but the so-called "fuel value," i. e., the heat of combustion less the unoxidized portion of the protein. In calculating the fuel values for the diets used in this research, two methods were employed. If the heat of combustion had not been determined, the energy derived from the protein, fat, and carbohy- drate, respectively, was computed by means of the standard factors of Rubner,3 the factor 4.1 being used for multiplying the grams of both the protein and the carbohydrate, and the factor 9.3 for multiplying the 'Armsby, The principles of animal nutrition, 2d cd., 1900. 2Emery and Benedict, Am. Journ. Physiol., 1911, 28, p. 301. 3Rubner, Zeitschr. f. Biol., 1885, 21, p. 377. ENERGY RELATIONSHIPS. 335 grams of fat in the diet. The sum of the calories found represented the total fuel value of the food. If, however, the heat of combustion of the diet had been determined, another method was followed. Since the heat of combustion of pro- tein is 5.5 calories per gram, the difference between 4.1 (the Rubner factor used for calculating the energy derived from protein) and 5.5, namely, 1.4, corresponds to the potential energy of the unoxidized por- tion of the protein molecule. With carbohydrates and fat the fuel value and the heat of combustion are essentially alike, although at times investigators have made slight allowances for the so-called "digestibility" of fat. Such correction of the values for fat is, how- ever, a questionable procedure, and thus in calculating the fuel value from the heat of combustion we need only make correction for the unoxidized protein. The loss of energy from the unoxidized protein was found by multiplying the protein in 1 gram of the food by 1 .4 (the potential energy of the unoxidized portion of the protein molecule) ; the resulting value deducted from the heat of combustion represented the fuel value of the diet per gram. (See table 50, page 124.) The fuel value of the total intake of food was then found by multiplying the grams of food ingested by the fuel value per gram. If we compare the fuel value of the diet with the subsequent increase in the heat production, we obtain a mathematical relationship which may properly be designated as the "cost of digestion." This designa- tion is in harmony with a convenient phraseology for similar relation- ships which is finding increased usage in all economic and many industrial processes and is beginning to be used by physiologists.1 For a true measure of the cost of digestion, it is necessary to have an accurate measure of the total heat production. We may not therefore content ourselves, as is too frequently done, with the simple measure- ment of the maximum or peak effect of the food ingested, but it is abso- lutely necessary to continue the measurements until the basal values are again reached and the total increment in the heat which is charge- able to the ingestion of the particular diet studied has been obtained for the entire period of measurement. Unfortunately, in a considerable number of our observations the experimental period was not continued a sufficient length of time to insure the return of the metabolism to the basal value and hence in the large majority of cases our measurement of the cost of digestion is a low rather than a maximum value. This should be taken into consideration in any estimate of our values for the cost of digestion. The data regarding the cost of digestion in the studies made of the various nutrients and diets have been collected and tabulated. 'See MacDonald, Proc. Roy. Soc. (B), 1915-17, 89, p. 394. 336 FOOD INGESTION AND ENERGY TRANSFORMATIONS. TABLE 249. — Cost of digestion of various food materials, calorimeter experiments. Food material, subject, and date. Total amount of food. Hours after food to end of experiment. Duration of experi- ment. Period of increment observed in experiment.1 Fuel value. Total incre- ment ob- served. Cost of diges- tion. CARBOHYDRATES. Sucrose. grams. hr. min. hours. hours. cats. cals. •p. ct. A. H. M...Apr. 1, 1907.. 191 8 15 8 6? 756 68 9 F. M. M. .Jan. 31, 1910.. 2100 4 48 5 3 2408 19 5 F. M. M. .Feb. 2, 1910.. 2100 4 0 4 3 2408 16 4 A. W. W..May 28, 1907.. 80 4 15 4 2 317 6 2 Maltrose-dextrose mixture. Dr. R Feb. 21, 1907.. 458 8 15 8 8 1,382 74 5 E. H. B...May 14, 1907.. 431 8 0 8 6 1,301 39 3 A. H. M...Mar. 28, 1907.. 307 8 30 8 8 927 94 10 A. L. L. . .May 13, 1907.. 299 8 15 8 4? 902 40 4 J. J. C... .Mar. 4, 1910.. 2145 3 43 4 3 2449 41 0 Bananas and sugar. H. R. D.. .Mar. 31, 1906.. 31,276 8 0 8 6 1,562 107 7 H. R. D.. .Apr. 21, 1906.. 31,274 10 15 10 10 1,561 137 9 A. H. M...Apr. 2,1906.. 31,207 8 0 8 8 1,448 94 6 A. L. L. . .Apr. 19, 1906.. 3862 12 15 12 6 1,147 72 6 A. L. L. . .Mar. 30, 1906.. 3864 8 0 8 4 1,109 88 8 J. J. C Apr. 7,1909.. 3725 3 32 4 4 962 69 7 F. M. M..Apr. 8,1909.. 3620 2 30 3 3 655 19 3 Bananas. Dr. H Feb. 14, 1910.. 403 2 38 3 3 409 27 7 F. M. M..Feb. 8,1910.. 400 .3 43 4 1 406 -2 0 Dr. H Feb. 17, 1910.. 397 3 41 4 3 403 21 5 Popcorn. A. H. M...Apr. 10, 1907.. 199 8 45 8 8 847 66 8 H. B. W...Apr. 9,1907.. 187 9 0 8 8 796 39 5 Rice (boiled). A. L. L. . .May 27, 1907.. 652 8 30 8 4? 432 "T t 2 FAT. Cream. J. J. C....Mar. 22, 1910.. 445 3 49 4 . . 1,362 -20 -1 D. J. M...June 7,1910.. 376 3 49 4 1,245 -2 0 D. J. M...June 3,1910.. 398 2 45 3 3 1,060 20 2 H. R. D...Mar. 28, 1906.. 399 8 0 8 8 860 18 2 A. H. M...Apr. 5,1906.. 345 8 0 8 4 766 73 10 A. L. L. . .Mar. 27, 1906.. 341 8 0 8 6 735 57 8 D. J. M...Mar. 23, 1910.. 221 1 39 2 . . 666 1 0 Butter and potato chips. A. H. M...Mar. 25, 1907.. 4454 8 15 8 8 3,202 125 4 E. H. B...Mar. 19, 1907.. 4316 7 15 6 6 1,924 57 3 L. E. E. ..Mar. 14, 1910.. "206 4 40 5 1,512 36 2 A. H. M...May 15, 1907.. 4218 8 15 8 4 1,503 28 2 A. W. W..Apr. 25, 1907.. 4189 9 0 8 4 1,276 15 1 J. R . Mar. 21, 1910 "187 4 43 5 5 1,266 11 1 J. J. C Mar. 12, 1910.. 4129 4 38 5 3 791 14 2 PROTEIN. Beefsteak. A. H. M...Apr. 5, 1907.. 777 9 0 8 8 1,305 136 10 A. W. W..Apr. 6, 1907.. 755 9 0 8 8 1,268 92 7 A. W. W..May 25, 1907.. 373 8 15 8 6 981 45 5 A. H. M...May 24, 1907.. 384 8 15 8 6 644 70 11 J. R Dec. 4, 1908.. 418 9 30 8 8 603 104 17 F. M. M. .Dec. 10, 1908.. 217 9 15 8 3 364 24 7 F. M. M. .Dec. 23, 1908.. 208 7 0 6 5 349 17 5 L. E. E Ian. 17, 1910.. 163 7 30 5 5 245 47 19 F. M. M. .Jan. 20, 1910.. 132 7 0 5! 2 221 10 5 ENERGY RELATIONSHIPS. 337 TABLE 249 (continued).— C0s< <>f i- of various food materials, calorimeter experiments. Food material, subject, and date. Total amount of food. Hours after food to end of experiment. Duration of experi- ment. Period of increment observed in experiment.1 Fuel values Total incre- ment ob- served. Cost o diges- tion. PROTEIN — cont. Beefsteak and bread. grams. hrs. min. hours. hours. cals. cals. p. ct. F. M. M. .Jan. 11, 1910. 6296 1 15 5 5 480 44 9 F. M. M. .Jan. 12, 1910. 6237 6 0 5 2? 415 32 8 F. M. M. .Jan. 14, 1910. ^225 6 15 5 5 399 46 12 Beefsteak and potato chips. J. J. C May 11, 1911. 6311 10 0 6 4} 676 43 6 A. G. E. ..Jan. 23, 1911. 6292 3 45 3 3 566 12 2 V. G Jan. 21, 1911. 6235 4 0 3 3 463 21 5 C. H. H...Jan. 18, 1911.. 6233 3 30 3 3 460 15 3 J. C. C....Jan. 17, 1911.. 6213 3 30 3 3 425 28 7 Glidine. J. R May 10, 1910 770 4 15 4 4 7267 40 15 J. R May 5,1910.. 70 4 30 4 4 262 51 19 J. J. C May 9, 1910.. 45 5 0 4 4 168 38 23 L. E. E. . .May 3, 1910.. 45 4 30 4 4 168 13 8 L. E. E. . .May 11, 1910.. 45 3 30 3 3? 168 5 3 Gluten and skim milk. H. R. D.. .May 17, 1906.. 8652 12 0 12 12 809 143 18 H. C. K...May 7,1906.. 8772 8 0 8 8 558 55 10 H. R. D...May 2, 1906.. 8321 8 0 8 8 496 51 10 H. R. D. .May 9,1906.. 8320 12 0 12 10 487 76 16 Plasmon and skim milk. H. R. D.. .May 4, 1906.. 9376 8 0 8 8 758 77 10 H. C. K. . .May 15, 1906.. 9586 12 15 12 10? 728 62 9 MIXED NUTRIENTS. Milk. H. R. D.. .Mar. 21, 1906.. 608 8 0 8 6 444 11 2 A. H. M...Mar. 23, 1906.. 607 8 0 8 6 385 51 13 A. L. L....Mar. 22, 1906.. 607 8 0 8 6 382 59 15 Supper. H. L. H...June 14, 1910.. 1,131 6 15 5 4 1,731 77 4 Heavy breakfast. A. H. M...Feb. 16, 1906.. 1,779 9 45 8 8 4,378 186 4 A. H. M...Feb. 19, 1906.. 1,633 9 30 8 8 3,936 229 6 H. R. D.. .Feb. 21, 1906.. 1,779 9 45 8 8 3,697 148 4 H. R. D.. .Feb. 17, 1906.. 1,828 9 30 8 8 3,311 181 6 A. L. L. . .Feb. 13, 1906.. 1,365 9 30 8 8 2,720 162 6 A. L. L. . .Feb. 15, 1906.. 1,196 9 30 8 8 2,142 96 4 Heavy supper. H. R. D.. .Apr. 10-11, 1906 1,664 19 15 20i 191 3,442 334 10 A. L. L . . . Apr. 6- 7, 1906 1,273 14 30 16 14* 2,364 281 12 These periods represent in each case the portion of the experiment in which increment of heat occurred as confirmed by increase in either or both of the other factors of metabolism. In experi- ments where no estimate is given, either the period of increment was not clearly defined or the amount of increment was actually negative. 2Also juice of one lemon; additional energy (11.5 cals.) included in fuel value. 'Amounts include sugar as follows: H. R. D., 103 grams each day; A. H. M., 86 grams; A. L. L., 99 grams each day; J. J. C., 77 grams; F. M. M., 9 grams. 4Amounts include potato chips as follows: A. H. M., March 25, 1907, 211 grams; May 15, 1907, 105 grams; E. H. B., 233 grams; L. E. E., 114 grams; A. W. W., 104 grams; J. R., 92 grama; J. J. C., 91 grams. 'Amounts include bread as follows: January 11, 50 grams; January 12, 38 grams; January 14, 24 grams. •Amounts include 20 grams potato chips, except for J. J. C., May 11, 1911, 41 grams. 7Also juice of one-half lemon; additional energy (5.6 cals.) included in fuel value. 'Amounts include gluten as follows: H. R. D., May 17, 1906, 153 grams; May 2 and 9, 1906, 100 grams each day; H. C. K., 66 grams. 'Amounts include plasmon products as follows: H. R. D., 170 grams; H. C. K., 147 grams. 338 FOOD INGESTION AND ENERGY TRANSFORMATIONS. Inasmuch as a considerable number of the calorimeter experiments continued for 8 or more hours and hence represent a fairly long period of time when the metabolism was measured, and, indeed, usually a much longer period than that represented by the respiration experiments, the data for the two classes of experiments are given separately, those for the calorimeter experiments being included in table 249 and those for the respiration experiments in table 250. We have, furthermore, TABLE 250. — Cost of digestion of various food materials, respiration experiments. Food material, subject, and date. Amount of food. Period of observation.1 Fuel value. Total increment observed.1 Cost of digestion. CARBOHYDRATES. Dextrose. K. H. A... May 14, 1912.. . grams. 2100 hrs. min. 4 7 cals. 2385 cals. 12 p. ct. 3 P. F. J May 15, 1912.. 2100 3 55 2385 6 2 Dr. P. R. . May 3, 1912. 2100 4 29 2385 19 5 J. C. C Dec. 31, 1912 3100 3 21 3380 12 3 J. J. C. . . . Mar. 7, 1911.. 3100 3 67 S380 35 9 L. E. E. . . May 29, 1911.. 3100 3 53 3380 18 5 C. H. H. . . May 1, 1911 3100 6 6 3380 24 6 H. L. H May 24, 1911... . 3100 3 41 3380 17 4 B. M. K... Dec. 30, 1912.. 100 6 0 374 21 6 A. J. O. . . Dec. 11, 1914 100 1 27 374 14 4 J. J. C Deo. 28, 1910 275 2 50 2292 8 3 V. G. . Dec. 29, 1910 275 2 49 2292 15 5 J. J. C Dec. 22, 1910.. . 375 1 43 3286 13 5 V. G Dec. 23, 1910.. 375 3 59 3286 19 7 Levulose. K. H. A. . . May 18, 1912. . 2100 3 38 2384 20 5 P. F. J. . . . May 22, 1912 2100 3 58 2384 20 5 J. P. C. . Apr. 3, 1911 3100 5 24 3379 36 9 L. E. E May 22, 1911 3100 3 51 3379 21 6 C. H. H May 16, 1911.. 3100 5 35 3379 34 9 H. L. H June 1, 1911.. 3100 5 13 3379 24 6 A. J. O. . Dec. 8, 1914. 100 1 29 373 12 3 J. J. C Jan. 4, 1911 275 1 15 2291 10 3 J. J. C Dec. 31, 1910. . . 75 6 47 280 38 14 Sucrose. Prof. C Nov. 20, 1909. 4100 1 4 4422 15 4 Prof. C. . Nov. 22, 1909 4100 1 42 4422 16 4 H. H. A. Jan. 2, 1912 2100 3 44 2408 36 9 L. E. E May 15, 1911.. 3100 2 34 3402 24 6 A. F. G. . . May 20, 1911 3100 3 52 3402 30 7 C. H. H. . . May 10, 1911 3100 3 3 3402 28 7 H. L. H. May 17, 1911 3100 3 7 3402 23 6 A. J. O Dec. 29, 1914.. 100 1 30 396 26 7 J. J. C Dec. 6, 1910 275 5 39 2309 27 9 J. J. C Dec. 8, 1910 275 2 3 2309 11 4 J. J. C Dec. 20, 1910 275 2 52 2309 16 5 V. G Nov. 18, 1910 275 1 34 2309 9 3 V. G Nov. 30, 1910 275 3 54 2309 21 7 J. J. C Nov. 22, 1910 375 1 11 3303 10 3 V. G Nov. 21, 1910 373 2 36 3295 12 4 Lactose. K. H. A. . . May 23, 1912 2100 3 12 2385 10 3 L. E. E . June 5, 1911 6100 4 5 6381 22 6 C. H. H May 23, 1911... . 3 100 4 30 3379 22 6 H. L. H June 7, 1911.. 3 100 3 38 3379 18 5 A. J. O. . . . Jan. 4, 1915.. 100 1 32 374 19 5 ENERGY RELATIONSHIPS. 339 TABLE 250 — Cost of digestion of various food materials, respiration experiments. — (Continude) . Food material, subject, and date. Amount of food. Period of observation.1 Fuel value. Total increment observed.1 Cost of digestion. PROTEIN. Beefsteak. J J. C Apr. 25, 1911.. . grams. "377 hrs. mins. 5 16 cals. 6790 cals. 81 p. ct. 10 H. L. H. May 20, 1914.. 317 1 58 532 13 3 H L. H July 1, 1911 . 249 11 42 418 138 33 H G. E Dec. 12, 1914. . 200 2 51 336 25 7 J. F. M . . . Apr. 23, 1914 198 2 19 332 19 6 J. K. M. . . Nov. 26, 1912 196 3 3 329 28 9 J. J. C . . Nov. 3, 1910 150 4 8 314 51 16 D. M Oct. 28, 1911 7182 5 11 7305 86 28 Dr. S. . June 30, 1911. . .. 177 6 35 298 56 19 A. J. O Nov. 17, 1914. 173 2 44 290 17 6 V. G. Nov. 4, 1910 150 2 39 281 24 9 V. G. Nov. 7, 1910 150 4 19 245 38 16 J J. C Nov. 8, 1910 150 3 12 234 13 6 MIXED NUTRIENTS. Milk (whole). H. F T July 14, 1911 500 4 5 358 11 3 Mixed diet. J J C Feb. 28, 1911 750 4 52 796 45 6 A. F .Apr. 20, 1915 344 3 27 468 19 4 1From the time when subject finished eating to the end of the last observation, except in casea when the increment of heat ended earlier. For details and method of computation, see tables 126 to 168, 215, 234, 246, and 247; also pp. 151 and 152. 2Also juice of one lemon; additional energy (11.5 cals.) included in fuel value. 3Also juice of one-half lemon; additional energy (5.6 cals.) included in fuel value. 4Also 200 grams coffee; additional energy (26 cals.) included in fuel value. 'Also juice of two-thirds lemon; additional energy (7.6 cals.) included in fuel value. •Includes 15 grams potato chips. 7 Also a little butter; not included in amount or fuel value. subdivided the experiments according to the preponderance of carbo- hydrate, protein, or fat in the several diets. The experiments in each group have been arranged according to the fuel value of the food intake. The data given in table 249 for the calorimeter experiments will be considered first. To indicate when the effect of the ingestion of food ceased, the dura- tion of the increment has been included in table 249. Frequently the basal metabolism was not reached before the experiment ended ; under these conditions the value given is doubtless too low, for it is impossible to assume that the period of increment was coincident with the length of the experiment. In many instances, however, the duration of incre- ment was considerably shorter than the total experimental period. This was true in the calorimeter experiments with sucrose, the only pure carbohydrate studied with the calorimeter. It may be noted that a number of 24-hour experiments with mixed diet have been omitted from this table. While the basal value was determined during a complete fast, it seems necessary to recognize the 340 FOOD INGESTION AND ENERGY TRANSFORMATIONS. fact that the subsequent ingestion of food is made under conditions materially different from those of the procedure followed in practically all our experiments, since after a 24-hour fast the stimulating action of the food must first counteract the depressing effect of fasting. Experi- ments made under these conditions are hardly comparable with those made after only 12 hours without food, and the experiments with a basal value of 24 hours or more of fasting have not been included in the table. The fuel values for the diet are at times extraordinarily high. Thus, in the experiment of February 16, 1906, the subject consumed a break- fast of mixed diet having an actual fuel value of approximately 4,400 calories. In several other instances the fuel value wras over 3,300 cal- ories. In general, however, it was not far from 500 to 1,200 calories. The total increments, also given in table 249, varied from minus val- ues (which are obviously due to faulty technique, defects in the deter- mination of the basal value, or undue activity in the basal period) to the increment of 334 calories noted in a heavy supper experiment. Of special significance is the relationship between the total increments and the fuel values of the food intake, i. e., the cost of digestion. The highest noted is that of 23 per cent for an experiment with J. J. C. on May 9, 1910, with glidine. Values above 10 per cent appear chiefly in the protein experiments, thus emphasizing strongly the fact that the ingestion of protein causes not only an actual maximum increase in metabolism higher than values obtained with the other nutrients, but a greater proportional increase when compared to the fuel value of the intake. Striking irregularities may be noted, and even with protein we find values under 10 per cent as frequently as above 10 per cent. With bananas and sugar the cost of digestion is relatively high in practically all instances, averaging about 7 per cent. In the one experi- ment in which it is low, namely, 3 per cent with F. M. M. on April 8, 1 909, there was an ingestion of but 9 grams of sugar. It is possible that the low increment of 19 calories noted on that date in a 3-hour observa- tion may have been due to the fact that the superimposed effect of the cane sugar included in the diet on the other days was here absent. On the other hand, on the days when bananas alone were eaten, the two experiments with Dr. H. showed a cost of digestion of 5 and 7 per cent. Still another experiment made with F. M. M. showed no change. While averaging results as diversified as those recorded in this table may appear to be a questionable procedure, yet we may tentatively state that the cost of digestion, or the relationship between the fuel value of the intake and the increase in the heat production due to the ingestion of food is, with carbohydrates, not far from 6 per cent on the average. With fat, aside from the two high values found with cream in the experiments with the subjects A. L. L. and A. H. M. in the spring of 1906, a small cost of digestion is noted, the average being not far from 2 per cent. With protein, although wide differences are found, the ENERGY RELATIONSHIPS. 341 values ranging from 2 to 23 per cent, the average value is approximately 10 per cent. The three experiments with milk on March 21, 22, and 23 were planned to be comparable as the same amount of milk was given the subjects; the fuel value ranged from 382 to 444 calories. The incre- ments obtained are somewhat irregular. A minimum of 11 calories was found with H. R. D. on the first day and fairly comparable values of 59 and 51 calories, respective^, were obtained on the two succeeding days. The fuel value of the milk taken in the last two experiments was practically the same. We see no reason for omitting the experi- ment on the first day, and hence the three experiments represent an average cost of digestion of milk of approximately 10 per cent. In the previous comparisons, the fuel value did not exceed approxi- mately 1,900 calories, except in one experiment with butter and potato chips, in which the intake of energy was 3,202 calories. In a group of experiments with an excess amount of food, characterized as "heavy- breakfast" experiments, the fuel value ranged from 2,142 to 4,378 calories. The cost of digestion in these experiments was fairly uniform, ranging from 4 to 6 per cent, with an average of 5 per cent. There were also two experiments of much longer duration than any of the other experiments included in this table, viz, those with H. R. D., April 10-11, and A. L. L., April 6-7, in which "heavy suppers" were taken with high fuel values. The cost of digestion was 10 and 12 per cent respectively. These higher figures may be due to faulty basal values or unusual activity in the food experiment, or the experiments may have been long enough to obtain all the increment which actually took place. They do not lend themselves, however, to very critical analysis. Under ordinary conditions the normal individual rarely eats a meal containing a pure nutrient or a meal in which there is an excessive pro- portion of any single nutrient, but usually a fairly balanced combina- tion of nutrients. It is accordingly of considerable practical signifi- cance that the six experiments with a heavy breakfast show such uniform percentages. While the use of average figures for the several groups of carbohydrates, fats, and proteins may be somewhat question- able, with mixed diets we may fairly state that the excess heat produc- tion as a result of ingesting such a diet is 5 per cent of the fuel value of the intake. In all of the heavy-breakfast experiments, the basal metabolism was not reached during the experimental period; the value of 5 per cent is therefore probably somewhat low and a value of 6 per cent would be more nearly in accord with the actual facts. We sug- gest, therefore, that as a general factor a heat production equivalent to 6 per cent of the fuel value may be expected as the result of the inges- tion of a mixed diet. 342 FOOD INGESTION AND ENERGY TRANSFORMATIONS. The respiration experiments, summarized in table 250, were primarily designed to study the maximum effect rather than the total increment, and were therefore shorter than the calorimeter experiments. With the exception of one experiment with a mixed diet and one with beefsteak and potato chips, the fuel value of the diet did not exceed 600 cal- ories, this value being much smaller than that of the diets used in the calorimeter experiments. The duration of the increment was also shorter, although it is evident that in many instances the basal value had not been reached at the end of the experimental period. The values given in such cases may be partial rather than maximum. The large number of experiments with relatively pure carbohydrates permits a comparison of the values for the different kinds of carbohy- drate. With dextrose it is seen that the cost of digestion ranges from 2 to 9 per cent, the average for 14 experiments with 11 subjects being 5 per cent. With levulose the total increments ranged from 3 to 9 per cent, and with one somewhat unreliable subject (J. J. C.) rose to 14 per cent. The average for 9 experiments with 8 subjects is thus approximately 7 per cent. With sucrose, the total increment varied from 3 to 9 per cent, with an average for 15 experiments with 9 subjects of 6 per cent. With lactose the total increment ranged from 3 to 6 per cent, with an average for 5 experiments with 5 subjects of 5 per cent. If we compare the experiments on the basis of the amount of sugar ingested, we find that the average cost of digestion was practically the same for both 100 grams and 75 grams. The only exception was sucrose, which gave an average cost of digestion of 6 per cent for 8 experiments with 100 grams and of 5 per cent for 7 experiments with 75 grams, the average for all experiments being 6 per cent. It is thus seen that the cost of digestion for the carbohydrates studied in these 43 respiration experiments does not differ materially in the proportion of increase, averaging not far from 6 per cent (5.5 per cent to be exact) of the fuel value of the intake. This figure, 5.5 per cent, is almost precisely the average obtained in 22 calorimeter experiments (5.6 per cent), although in those experiments mixed carbohydrates were taken, such as bananas, popcorn, and rice, rather than pure car- bohydrates. A relatively large number of respiration experiments were made with the protein-rich food, beefsteak, in which the fuel value1 ranged from 234 to 532 calories, or 790 calories if we include the experiment with beefsteak and potato chips. A strict averaging of these experiments is not permissible, owing to the differences in the time relations. Large increments are noted in several instances with several values for the 'It should be noted that the beefsteak used in these experiments contained a certain proportion of fat, which supplied from 24 to 37 per cent of the fuel value. Consequently, the cost of digestion of the protein itself is not represented by the figures given. In all probability the true value would be higher. ENERGY RELATIONSHIPS. 343 cost of digestion of 16 per cent or more. The average cost of digestion for all of the beefsteak experiments is 13 per cent, more than twice the value observed with the carbohydrates. In the experiment with whole milk, a cost of digestion of 3 per cent was found, while the two experi- ments with a mixed diet gave values of 6 and 4 per cent, respectively, these being not far from the values obtained for the calorimeter experiments. Emphasizing again the fact that in drawing conclusions from the results given in these two tables it should be remembered that the figures given are low rather than maximum values, since in the majority of instances the basal value was not reached before the conclusion of the experiment, we may conclude that the average cost of digestion for the ingestion of pure carbohydrates or a predominatingly carbohydrate meal will be not far from 6 per cent of the fuel value of the food ingested. With fat it is approximately 2 per cent and with a protein-rich diet it averages 12 per cent. With a mixed diet, which more property corre- sponds to every-day usage, 6 per cent is doubtless near the correct value. SPECIAL RELATIONS OF PROTEIN DIETS TO ENERGY TRANSFORMATIONS. With diets consisting primarily of carbohydrates and fat no special indices are available as to the proportion of fat and carbohydrate burned in the body other than the relationship between the carbon- dioxide production and the oxygen consumption; but when protein enters into the katabolism, especially in excessive amounts, the nitro- gen in the urine has commonly been taken as an index of the amount of protein katabolized. The intimate relationship between protein katab- olism and heat production has been so pronounced as to lead writers to calculate quantitative relationships between heat production and the nitrogen excretion of the urine. In the computation of the total energy transformation by means of the respiratory exchange, emphasis is laid for the most part upon the measurement of carbon-dioxide excretion and oxygen consumption, and heat production is computed from the calorific value of the carbon- dioxide or oxygen at the respiratory quotient actually measured. There are two methods for computing heat production from the calo- rific values for carbon dioxide and oxygen. In one no special attention is paid to the protein disintegration, on the general ground that usually about 15 per cent of the total energy is derived from protein metabo- lism. When a high degree of accuracy is desired, however, it is custom- ary to compute from the respiratory exchange and the nitrogen in the urine the non-protein respiratory quotient, then compute the energy production due to the katabolism of the protein by multiplying the number of grams of nitrogen in the urine by a standard factor (26.51 344 FOOD INGESTION AND ENERGY TRANSFORMATIONS. calories). The remainder of the energy is then apportioned between fat and carbohydrate on the basis of the non-protein respiratory quo- tient. As previously stated (see page 203) , this was not done in our com- putations of the energy from the gaseous exchange, as the non-protein quotient has relatively little significance, save in those experiments in which an excessive amount of protein was ingested. By using the nitrogen excretion as an index of the protein katabolized, computing the total energy derived from protein and comparing it with the increment in the energy due to the ingestion of a protein food, cer- tain relationships are made possible. This method of computation may be illustrated by using the results of the experiment with A. H. M. on April 5, 1907, in which 777 grams of beefsteak were taken by the subject. (See table 198, page 267.) The basal nitrogen excretion used was 1.06 grams per 2 hours (see table 28, page 80). The nitrogen excretion in the first 2-hour period following the ingestion of the food was 4 grams. The increment in the nitrogen excretion due to the in- gestion of this large amount of a protein food was therefore 2.94 grams. As each gram of nitrogen in the urine represents a heat production from protein katabolized of 26.51 calories, the increment of 2.94 grams of nitrogen represents 78 calories of energy due to the increase in the amount of protein katabolized during this 2-hour period. Inas- much as the total increment in heat production for the first period was but 31 calories, it is evident that at least 47 calories from the protein combustion took the place of energy originally derived from carbohydrate-fat combustion in a 2-hour period of the basal experi- ment. The total nitrogen excretion in the 8 hours of the experiment was 11.49 grams; the excess nitrogen excretion was therefore 7.25 grams, with an energy production of 192 calories due to the increase in the protein katabolized. The total increment in the heat pro- duction was but 136 calories; we may assume, therefore, that the re- placement of basal energy derived from material other than protein was at least 56 calories. The direct measurement of the protein disintegration from the nitrogen in the urine leads to the possibilities of further computation to determine the cause of the increase in the energy output following the ingestion of food. For example, when a protein food, such as beefsteak, is given in an experiment, we may compare the subsequent total increase in the metabolism (1) with the total energy of the food intake; (2) with the fuel value of the intake, thus obtaining the "cost of digestion"; (3) with that portion of the total energy or fuel value of the diet which is derived from protein alone; (4) with the total energy of the katabolized protein; or (5) with the increment in the heat production due to the increase in the amount of protein katabolized. In the experiment with A. H. M. on April 5, 1907, the total effect of the ingestion of beefsteak wasnot obtained, as there was still a consider- ENERGY RELATIONSHIPS. 345 able increment in the metabolism even in the last period. We can not use the results, therefore, for an illustration of computing the specific dynamic action.1 An experiment better adapted for this purpose is that with the same subject on May 24, 1907, in which the basal metab- olism was obtained in the last period of the experiment and the total increment due to the ingestion of the beefsteak was therefore secured. ( See table 200 , page 269 . ) Following the usage of Rubner , the fuel value rather than the total energy of the diet may be used in the computa- tion. The fuel value of the beefsteak eaten in this experiment was 644 calories, of which 70 per cent was derived from protein, or approxi- mately 450 calories. The total increase in the heat production subse- quent to the ingestion of the food was 70 calories. The total nitrogen excretion in the 8 hours of the experiment was 8.26 grams; as the basal nitrogen excretion which may be used for the same period is 4.24 grams, the excess nitrogen excretion due to the ingestion of the food was therefore 4.02 grams. This corresponds to an excess in the amount of protein katabolized (4.02 by 26.51) of approximately 107 calories as the result of an intake of 450 calories from protein. A part of this increment of 70 calories may be properly ascribed to the influence of fat ingestion, since there was a considerable proportion of fat present in the beefsteak, but our evidence, as well as that of other investigators, indicates that the ingestion of fat has but a slight effect upon the metabolism and may probably be neglected in computations of this kind. Indeed, this was done in computing the values given in tables 249 and 250. The possibilities of differentiating between fat and protein in determining the influence upon the metabolism of the inges- tion of a protein-fat diet should not, however, be lost sight of. It may be noted in this connection that Rubner carefully made such corrections in considering the influence of the protein-fat diets used in his experi- ments. The experiments in our research with a predominatingly protein diet were not sufficiently extended or carried out with a sufficient degree of accuracy to justify a computation from their results of the so-called ''specific dynamic action" of protein in the case of man. There is no question but that such a relationship exists between the increment in the protein katabolism and the increment in the heat production, but it may or may not be causal. Our experiments show that subsequent to the ingestion of a diet containing an excessive amount of protein there is prolonged and excessive heat production which continues for several hours. The nitrogen in the urine is likewise increased, although, as is seen from the foregoing discussion, the increase in heat production is 'Williams, Riche, and Lusk (Journ. Biol. Chem., 1912, 12, p. 352) have pointed out in an in- teresting manner the methods of computing the specific dynamic action, so called, from an increase in the protein katabolism. 346 FOOD INGESTION AND ENERGY TRANSFORMATIONS. not sufficient to account for the total excess protein katabolized.1 The fact should be recognized that this relationship is more apparent than real, for an increment in heat production is likewise found as the result of the ingestion of carbohydrates which is unaccompanied by material changes in the nitrogen excretion; one must therefore be cautious in associating too intimately the increase in the heat production with the increase in the amount of nitrogen excreted in the urine. CAUSES OF INCREASE IN METABOLISM SUBSEQUENT TO INGESTION OF FOOD. In the light of present knowledge, it would appear as a subject for severe criticism that an investigation on the influence of the ingestion of food upon metabolism which continued for a decade should show such relatively slight positive evidence contributing towards an expla- nation of the various phenomena observed. It was hoped that, as the research developed, definite information as to the cause or causes of the increase in the metabolism would be accumulated. Thus, in the earlier part of our research, impressed by the strength of the argument pre- sented by Zuntz and his associates upon the influence of roughage or crude fiber in the diet, we included experiments with popcorn in our study on the influence of pure carbohydrates, on the supposition that the starch of the popcorn and the crude fiber of the hull would give roughage. As the research continued, however, it was found impossible to plan experiments, save under special conditions, for studying the cause of the increased heat production following the ingestion of food. Consequently our data represent for the most part only faithful records of a large number of experiments in which foodstuffs were given, either singly or combined, and the energy transformations subsequently measured. A careful search in our data for conclusive evidence as to the cause of this rise in the metabolism is, however, unsuccessful. At the present time three explanations are offered of the increases noted with the ingestion of food. Zuntz and his associates, influenced largely by their extended experience with domestic animals, particu- larly with ruminants which consume considerable roughage and bulky food materials that remain for a long time in the intestine and require considerable digestive activity expressible in forms of muscular activity, maintained that the increase was due to the work of digestion, or Verdauungsarbeit. Rubner, as a result of his critical series of experi- ments on dogs, particularly the experiments with protein, was not inclined to attribute any share of the increase to the work of digestion, 'Attention should here be called to a recent study on the basal metabolism of dwarfs and legless men (Aub and E. F. Du Bois, Arch. Intern. Mod., 1917, 19, p. 864), in which the authors say that "following the ingestion of large quantities of meat, the excretion of urinary nitrogen during the earlier hours is not an accurate index of the protein metabolism. The sulphur excretion is more rnpid tVnn tho nitro^on ENERGY RELATIONSHIPS. 347 but explained the increase upon the theory that each foodstuff exhibited a specific dynamic action, believing that the elaboration of food materials preparatory to absorption and oxidation, particularly the cleavage and elaboration of the protein molecule, accounted for the excess heat production. More recently the hypothesis of Friedrich Mueller1 has been revived,2 in that it has been maintained that the increase in the heat production is due to a stimulus to the cells as the result of products obtained from the food materials ingested or elabo- rated from them. That these products are in all probability of an acid nature is evidenced by experiments from this laboratory; the influ- ence of amino-acids has been definitely proved by Lusk.3 Although practically none of our experiments were ideally planned to determine definitely the cause of this increase, certain phases of the work should be considered as an attempt to find if the phenomena agree with any of these explanations. Our experimental plan included, first, the establishment of a base-line, and second, a post-absorptive condi- tion for the subject in each experiment, i. e., that the subject should have been without food for at least 12 hours. It was assumed that comparison with such a base-line would give a true measure of the increase in metabolism due to food. The various factors affecting the basal metabolism have been considered in detail elsewhere4 and likewise in our chapter on basal metabolism. (See page 47.) It is of interest to point out here, however, that even after the active digestion of food has ceased, Gigon concludes that there is consid- erable internal work which is characterized by Zuntz as Verdau- ungsarbeit. Indeed, Gigon ingeniously ascribes a depression found by him in the metabolism following the ingestion of 50 grams of olive oil as being due to the fact that the presence of the oil caused an abatement of the Verdauungsarbeit which had persisted during the experimental period. Furthermore, X-ray studies have definitely proved5 that even during relatively prolonged fasting the motility of the stomach and the intestines does not entirely cease ; this was like- wise found by Boldireff.6 In discussing the influence of the ingestion of food, it is especially necessary to bear in mind this activity of the digestive organs during the absence of food, including the movements of the alimentary tract, the secretion of the various digestive juices, and similar movements, for the ingestion of food may be supposed to increase the activity of all these factors. r, Volkraann's Sammlung klin. Vortrage, May, 1900 (N. F. No. 272), p. 17. 'Benedict, Trans. 15th Int. Cong. Hygiene and Demography, 1913, 2 (2), p. 394. 'Lusk, Journ. Biol. Chem., 1915, 20, p. 555. 4Benedict, Emmes, Roth, and Smith, Journ. Biol. Chem., 1914, 18, p. 139; Benedict and Roth, Journ. Biol. Chem., 1915, 20, p. 231; Benedict and Smith, Journ. Biol. Chem., 1915, 20, p. 243; Benedict and Emmes, Journ. Biol. Chem., 1915, 20, p. 253; Benedict, Journ. Biol. Chem., 1915, 20, p. 263. 'Cannon, The mechanical factors of digestion, 1911. 6Boldireff, Arch. d. Sci. Biol., 1905, 11, p. 1. 348 FOOD INGESTION AND ENERGY TRANSFORMATIONS. Any evidence bearing upon the possibility of intensive peristalsis or digestive action, or any series of experiments in which such stimulating agencies may be present, are of special interest in considering the cause for increased metabolism following food. Thus it is conceivable that the starchy foods would be more slowly acted upon than sugars, and yet an examination of the results of our experiments with such foods shows that they produced nearly as great an increment as the sugars did. (See tables 123, 124, 249, and 250, pages 196, 199, 336, and 338.) This is indeed surprising and might logically be taken as evidence in favor of the Verdauungsarbeit theory. While the dry starch of the popcorn could reasonably be considered as requiring a large amount of digestive work, it is hardly possible that bananas would contain material sufficiently irritating to the intestinal canal to have a great effect upon peristalsis or segmentation. At least two series of experi- ments carried out in this laboratory indicate that intestinal activity, as exemplified by the action of smooth muscle, does not measurably affect the metabolism. In one series the effect of purgatives and agar-agar was studied,1 and in the second a study was made of the metabolism of dogs with ablated pancreas and consequently deficient digestibility.2 In view of the results obtained in these two series of experiments, we find it unconvincing to explain any portion of the increase subsequent to the ingestion of food as being due to Verdauungsarbeit in the sense in which Zuntz uses the term. All writers who discuss the cause of the increase in heat production following the ingestion of food are at once confronted by the problem of giving a concrete explanation of the term " specific dynamic action," first used by Rubner. Perhaps no worker has considered this subject more in detail than Lusk, who has written one of the best expositions of Rubner's views that has ever been published.3 Lusk proposes to compare the increase in heat production with the increased protein katabolized as a measure of the so-called " specific dynamic action," a process which is radically different from that originally employed by Rubner.4 Great difficulty is immediately experienced when we attempt to consider our experimental evidence in accordance with the prevailing views as to the cause of the increased heat production following food. Our experience with diabetics and with normal persons with a normally induced acidosis on a carbohydrate-free diet, as well as our experiments with unoxidizable material in the intestinal tract, lead us to favor more strongly the theory of acid-body stimuli, but it would be clearly a misuse of this present series of experiments to attempt to use them as experi- 'Benedict and Emmes, Am. Journ. Physiol., 1912, 30, p. 197. 'Benedict and Pratt, Journ. Biol. Chem., 1913, 15, p. 1. 'Lusk, Science of Nutrition, 3d ed., 1917, p. 232, et seq. 4Williams, Riche, and Lusk, Journ. Biol. Chem., 1912, 12, p. 349. ENERGY RELATIONSHIPS. 349 mental evidence for any of the three current theories. It is of signifi- cance that popcorn and bananas, with their large content of fiber material, increase the metabolism, a fact which tends to support the Verdauungsarbeit theory. The well-known increases in peristalsis sub- sequent to the ingestion of pure sugars, especially levulose, would also probably be considered by the advocates of the Verdauungsarbeit theory as sufficient explanation of the increment noted with sugars. On the other hand, the results of the two studies previously referred to, in one of which excessive peristalsis was induced by the administration of Glauber salts and agar-agar to man, and in the other a study was made of the metabolism of dogs having defective assimilation due to ablated pancreas, strongly disprove the Verdauungsarbeit theory. GENERAL CONCLUSIONS. Many of the conceptions as to the influence of the ingestion of food upon the heat production have long been held and need no material modification. But as most of such evidence was obtained in experi- ments with animals rather than with men it seemed desirable for us to undertake a research upon the influence of the ingestion of food upon the metabolism of man. In making these experiments we have been greatly indebted to the earlier investigators, more especially to Magnus- Levy1 and to Johansson and his school,2 as their researches were in large part with men. It has been impracticable in our discussion to cite adequately the numerous observations made upon animals, particu- larly the classic experiments of Rubner and the more recent work of Lusk and his associates in New York. Believing that our problem was sufficiently extended if confined primarily to man, we have therefore intentionally omitted in this publication a review of practically all experiments made upon animals. In the decade or more that the results have been accumulating, numerous papers by other investi- gators have appeared, many of them reporting experiments with men. These we have considered carefully in our digest of the literature, as well as in the discussion of the several chapters. The experimental evidence in this book as a result of our research presents little that is startlingly new. The mechanical work of chewing has been found to produce a definite increase in the metabolism. The drinking of liquids, especially in large amounts, likewise has been shown to increase the metabolism, although these increases are usually relatively small. The fact that the ingestion of all kinds of food in any amount results in an increment in the metabolism seems very clearly established. No conclusive evidence of a metabolism depressed below Magnus-Levy, Arch. f. d. ges. Physiol., 1894, 55, p. 1. 2 Johansson, Skand. Arch. f. Physiol., 1897, 7, p. 29; same journal, 1902, 13, p. 251; same journal, 1904, 16, p. 263; same journal, 1908, 21, p. 1. 350 FOOD INGESTION AND ENERGY TRANSFORMATIONS. the basal value after food has been found in any case. As our work was with man, it was obviously impracticable for us to use pure nutri- ents save in the case of sugars, and our experiments are thus open to this criticism. Hence, if we attempt to establish mathematical rela- tionships for the effects of carbohydrates, fat, and protein, we at once meet the criticism that while the carbohydrates selected were, for the most part, pure nutrients, the fat and protein food materials were mixed nutrients, as, for instance, beefsteak, in which the protein was combined with fat, which also supplied a certain amount of energy. Notwithstanding this defect in our experimental plan, the evidence obtained with diets in large part protein agrees with that secured by other observers with a protein diet, as an effect was found which was more pronounced and extended than that of any other nutrient. It appeared to make no difference whether the protein used was an ani- mal or a vegetable protein, for the experiments with glidine on the one hand and with beefsteak and plasmon on the other are usually comparable. Unfortunately the evidence obtained regarding fat is not so convinc- ing, for our experiments are admittedly too few in number to give con- clusive results and in the diets used the fat was combined with other substances; still the available energy derived from fat in the food intake was so large in most instances that the increment in the metabo- lism must necessarily have been due to this factor. Although the effect obtained was by no means so great as that found with protein, it can not be considered as negligible. The most sharply defined results were those secured in the series of experiments with carbohydrate diets. It was possible to make a care- ful analysis of these data, compare the results obtained with the indi- vidual carbohydrates, and determine not only the total effect upon the metabolism measured, but likewise the time relations and the rapidity of the action of the food material. These results show in a striking manner that all of the carbohydrates influence the total metabolism and differ but little in this respect, although levulose and sucrose appear to exert a somewhat more powerful influence than the other sugars. The experiments with mixed diets, especially those with excessive amounts of food, showed that it was possible by the ingestion of a large meal to stimulate the metabolism to 40 per cent above the basal value for a number of hours, and to 20 per cent for at least 8 hours; indeed, there was every reason to believe that the stimulus to the metabolism would have been found to continue considerably longer than the ex- perimental period of 8 hours if the observations had been prolonged. This fact has a special practical significance in its relation to the daily life of human individuals. While it is possible for a human being to live with greatly reduced activity when sound asleep, without food in the stomach, and without extraneous muscular activity, his efficiency ENERGY RELATIONSHIPS. 351 as a member of human society in such a state would be negligible. It is therefore only as the cellular activity increases that we find him becoming more and more of service to humanity, and not until he is erect and ready to perform active external muscular work is he in a condition to live on a basal plane that is of practical value. The ingestion of food with its attendant increase in metabolism appears at first thought like a highly inefficient process, this increase being comparable to the extra energy required by a donkey engine to stoke the boilers in a large factory ; so far as the direct mechanical out- put of the factory is concerned, the energy thus used appears as waste, and yet it is necessary in order to secure a supply of fuel to the boilers. The increment in the metabolism or excess energy given off by the body as a result of the ingestion of food may be considered as the energy re- quired for the preparation of material for use in the body tissues, and on this basis may be regarded as waste energy. Indeed, it is the belief of some writers that heat is invariably a waste product and that this factor has interest only in that it is developed in connection with mus- cular or glandular activity. Another phase of the situation appears, however, when we consider that the extra heat developed under these conditions may possibly be looked upon as a normal physiological stim- ulus to cellular activity. In this connection the practical experience of many investigators may be mentioned, especially those making ob- servations with severe muscular work in studies with a protein diet and, in many cases, with a carbohydrate diet, such as sugar or sweet choco- late. If it be true that the increase in the metabolism resulting from the ingestion of such diets has a specific influence in stimulating the whole cellular system of the body to greater activity, then we may not properly regard this excess heat as a waste product. Continuing the discussion in the terms of the efficiency engineer, it may be possible to consider the increase in heat production due to food as a measure of the " cost of digestion." For instance, the ingestion of 1,000 calories of food in the form of sugar requires the excess production of 60 calories of heat in order to have the sugar ready for an actual share in the muscular work. On this basis, one might compute that this excess heat was lost and that when 1,000 calories in the form of cane sugar are transformed into material ready for combustion in the body only 940 calories are available for such use. If, then, the increments in heat production obtained in our various experiments are computed and compared with the fuel value of the food ingested, .the proportion of the energy in the ingested food which was given off as excess heat may be determined. One great difficulty in securing such data is the fact that in many instances the experiments did not continue long enough to include the entire heat increment. This is particularly true in the pro- tein experiments, for frequently (see table 215, page 284) the basal value was not reached before the end of the experiment. 352 FOOD INGESTION AND ENERGY TRANSFORMATIONS. The data showing the relationship between the excess heat and the fuel value of the intake, which are given in tables 249 and 250 (see pages 336 and 338), vary considerably with the length of the experiment, the total amount of the food intake, and the nature of the diet. While, for lack of a better terminology, the values are designated as the "cost of digestion", the use of such a term is distinctly misleading, as imply- ing that this excess heat is waste heat. We are firmly convinced that the excess heat produced from the ingestion of protein or carbohydrates, like sugars, may not properly be considered as purely a waste process, but that it is far more logical to consider it as a general stimulation of all of the cells in preparation for the drafts of muscular activity. Our results give no basis for recommending an exclusively protein diet or an exclusively sugar diet prior to severe muscular work. That the presence of glycogen in the body has an important bearing on the efficiency of the muscular system is, in general, we think, proved with- out doubt. That any food substance that will contribute toward the replenishment of a depleted glycogen store or will maintain this at a high level is important in the preparation for muscular work, we like- wise may consider as being thoroughly established. The formation of glycogen from sugar is unquestionably proved; the formation of glyco- gen or sugars from protein is likewise demonstrated ; but there is as yet no evidence that sugar is formed from fat. It follows, therefore, that diets preceding muscular work should contain liberal quantities of carbohydrates or protein, although our evidence does not allow us to determine which is the more important, the furnishing of glycogen or the normal stimulus to the body. There is no question but that protein is a more prolonged stimulus to the metabolism than carbohydrate. On the other hand, in the digestion of protein extra work is thrown upon the organs of excretion. Too much significance may be given to this, but nevertheless, since the ingestion of carbohydrates does not require such work, there appears to be a legitimate ground for ques- tioning whether an excessive protein diet or an excessive carbohy- drate diet would be the more desirable to provide a glycogen storage as preparation for muscular work. The value of large diets of either protein, carbohydrate, or mixed nutrients to replenish the glycogen depots and stimulate the whole body to cellular activity is plainly shown by our experiments. The practical application of this fact would seem to lie more particularly in the preparation for those bodily activities calling for considerable muscular work. APPENDIX. SUGGESTIONS AS TO METHOD FOR STUDYING THE EFFECT UPON BASAL METABOLISM OF INGESTION OF FOOD OR DRUGS. In reporting the results of these investigations on the effect of the ingestion of food upon the metabolism, it seems appropriate, in view of our experience with various foods and numerous subjects during the past 12 years, to offer suggestions as to the methods to be employed for an ideal study of this prob- lem. These suggestions are based not only upon the actual work here re- ported, but also upon much experimenting carried on since most of this work was done. Objects. — We must first recognize the objects of such a study. These are the determinations of (1) the total effect upon the metabolism of the ingestion of food, namely, the increase above the basal metabolism; (2) the highest increase above the basal metabolism and its1 time relation to the taking of food, i. e., the peak effect; and (3) the subsequent character of the metabolism to note whether it remains unaltered or if there is a change in the proportions of protein, fat, and carbohydrate metabolized. Subjects. — It is obvious that the subjects selected should be primarily normal, healthy individuals, without tendency to digestive disturbances. Only through a knowledge of the metabolism of normal individuals can we gain information as to the abnormalities in the metabolism after food inges- tion under pathological conditions. Individuals who are likely to continue throughout an entire series of tests are to be preferred, as they may be depended upon for subsequent duplicate and control experiments. Repeated experiments with the same individuals obviate the necessity for training new subjects, lead to an improvement in the experimental routine, and reduce the number of subjects required for obtaining results which will supply definite conclusions. The training of pathological subjects is more difficult than the training of normal subjects; moreover, the physical condition of such subjects is liable to variation. A greater number of experiments is accordingly neces- sary for a series of investigations with pathological conditions. Basal metabolism. — Since the object of any study of the metabolism subse- quent to food ingestion is to determine the effect upon the basal metabolism, i. e., the metabolism in the post-absorptive condition (12 hours or more after the last food ingestion) , it is necessary first to obtain an accurate measure of the basal metabolism. As our own unfortunate experience only too frequently shows, it is imperative to determine the basal metabolism and the metabolism after food upon the same day, save perhaps in exceptionally prolonged experi- ments. When this is not done the basal metabolism determined on another day may be higher than the true basal metabolism of the food day, thus lead- ing to the conclusion that the effect of the food is negative. Furthermore, there should be a preliminary period of observation which should be con- tinued 30 minutes or preferably longer, so that one may state with certainty that the basal level has been reached before the actual measurements are begun. During this preliminary period the subject should be at rest and in the same body position as during the experimental period. 353 354 FOOD INGESTION AND ENERGY TRANSFORMATIONS. Control of external muscular activity. — It has been repeatedly stated in publications from this Laboratory1 that, in any study of metabolism in which comparable results are to be obtained, it is necessary to have as nearly as possible complete muscular repose and that there must be a graphic record which will indicate that such repose has been maintained throughout the periods of the experiments which are compared with each other. Such a graphic record may be obtained either by means of pneumographs around the thighs and thorax or by means of a pneumograph or pneumatic bulb con- nected to the bed support. If these devices are connected with a sensitive recording tambour, the slightest muscular movement of the subject results in a change in the volume of the air in the pneumograph, which is immediately recorded by the pointer of the tambour upon the smoked surface of the rotat- ing drum of a kymograph. In addition to the record of the amount of complete external muscular repose it is equally important to note any drowsiness or sleep which may occur during the measurement of the metabolism. Recent experience with human subjects in a series of experiments upon the metabolic effect of the ingestion of alcohol has shown that the degree of wakefulness can be satisfactorily recorded by having the subject press a push button periodically in response to a stimulus. The stimulus is supplied by a signal magnet which is operated once every half minute. The magnet is so placed that the subject can hear it readily and is in series with a battery, clock, and second signal magnet which records upon a moving kymograph drum. The push button operated by the subject is connected with a battery and an independent recording signal magnet, thus giving a record of the response to the signal. A continuous record of responses gives positive evidence of wakefulness on the part of the subject, while a continuous lack of responses is indicative of drowsiness or actual sleep. The effect of external muscular activity is to change the total metabolism, while the effect of drowsiness or sleep is to change the apparent character of the respiratory exchange; accordingly, a graphic record of both is essential for a reliable interpretation of the results obtained. Length of periods. — The length of the periods of observation is naturally dependent upon the total effect to be measured and upon the apparatus used. When the effect is exceedingly small, and particularly when the peak effect and its time relation are desired, it is essential to make the periods as short as possible, preferably 10 to 15 minutes. If an apparatus with a closed chamber is used, periods as short as these are not possible; with such an apparatus, periods of at least 30 minutes should be employed and 45-minute periods are more reliable. Apparatus. — From the experience of the last 12 years in studies of this character, we have come to the conclusion that some form of respiration apparatus is desirable with which it is possible to measure the gaseous exchange continuously in short periods. At present the best combination for this purpose with a trained subject is found to consist of a face mask, valves for separating inspired and expired air, two spirometers (preferably of the Tissot type), and a Haldane portable gas-analysis apparatus for analyzing the expired air. The face mask is one used in the Siebe-Gorman mine-rescue apparatus.2 To secure reliable results, the tightness of the mask against the face must be assured. The valves for separating inspired and expired air most used in this laboratory are the Thiry-Tissot model,3 but any valve which is •Benedict, Deutach. Arch. f. klin. Med., 1912, 107, p. 156; Benedict and Talbot, Carnegie Inst. Wash. Pub. No. 201, 1914, pp. 31 and 59; Benedict, Carnegie Inst. Wash. Pub. No. 203, 1915, p. 311. "This may be obtained from H. N. Elmer, 1140 Monadnock Building, Chicago, 111. 3Both the Thiry-Tissot valves and Tissot spirometer were obtained from Pirard and Coeurde- vaoho, 7 rue Blainville, Paris, France. SUGGESTED METHOD OF STUDY. 355 lightly movable and gives perfect closure without backlash is suitable. The spirometers are of the Tissot model. A complete description of this spirometer is given in a former publication from this Laboratory.1 Any spirometer which is lightly movable and fairly well counterpoised is practicable for this purpose. The 100-liter spirometer is the most adaptable for general use. The portable gas-analysis apparatus is the one devised by Haldane2 for the analysis of atmos- pheric, mine, and expired air. Its accuracy should be controlled by analyses of atmospheric air. The apparatus, when properly set up, should give 0.03 per cent CO2 and 20.93 to 20.95 per cent O2 for atmospheric air. We insist on this as a proof of the accuracy of the analysis of the expired air. Such analyses should be reported in connection with the results of metabolism measurements. With the combination of apparatus outlined in the foregoing paragraphs, a trained subject awake, and a complete absence of external muscular activity, it is possible to measure the peak effect of either the metabolism or of the respiratory quotient, or to measure the effects of the ingestion of exceedingly small amounts of material. During the past two years the gaseous exchange and respiratory quotients of trained subjects have been measured for 6 to 7 hours in consecutive experimental periods as short as 10 minutes, with no great degree of discomfort to the subject and with a high degree of accuracy. When the increments in metabolism are likely to be large and to extend over a considerable period of time, and when it is possible to repeat the experiment several times, the clinical respiration apparatus (a chamber apparatus)3 is probably the most feasible. In this apparatus it is not necessary for the sub- ject to remain absolutely immovable and the possibility of movement makes it pleasanter for the subject in long experiments. Summary. — From the foregoing it can be seen that the ideal method for determining the effect of the ingestion of food upon the metabolism is the use of trained subjects; a measurement of the basal metabolism on the same day as that following the ingestion of food ; an absolute absence of external muscu- lar activity; a subject awake; graphic records of both the absence of activity and any evidence of drowsiness or sleep; as short periods as possible; spiro- meters, respiratory valves, face mask, and portable Haldane gas-analysis apparatus, with determinations controlled by analyses of atmospheric air. lCarpenter, Carnegie Inst. Wash. Pub. No. 216, 1915, p. 61. 'Haldane, Methods of air analysis, 1912, p. 47. 'Benedict and Tompkins, Boston Med. and Surg. Journ., 1916, 174, pp. 857, 898, and 939. - .- - , -. - . ... -.. . . , -. - ^^^^^^H I I : S ..:-: ~... •---••