81 iiilliiB^^^^^^^ l^iii!: TX749 LIBRARY OF CONGRESS DDD027T33Ta 1018 Issued October 18, 1907. U. S. DEPARTMENT OF AGRICULTURE. OFFICE OF EXPERIMENT STATIONS— BULLETIN 193. A. C. TRUE, Director. STUDIES OF THE EFFECT OF ft DIFFERENT METHODS OF COOKING UPON THE THOROUGHNESS AND EASE OF DIGESTION OF MEAT AT THE UNIVERSITY OF ILLINOIS. BY H^SfGRINDLEY, D. Sc, I, Professor of General Chemistry, College of Science, Universitij of Illinois, WITH THE COOPERATION OF TIMOTHY MOJONNIER, M.S., AND HORACE C. PORTER, Ph. D. WASHINGTON: GOVERNMENT PRINTING OFFICE. 190T. a/ U^^ THE OFFICE OF EXPERIMENT STATIONS. STAFF. A. r. Tiu E, D. Sf., Director. E. W. Allen, Ph. D., Assistant Director and Editor of Experiment Station Bccord W. H. Beal, B. a., i\I. E., Chiif of Editorial Division. C. F. Lan'gwokthy, Ph. D., Chiif of Xutrition Invcstiaations. R. D. MiLNEii, Ph. D.. Assistant in Nutrition Investigations. (2) • . WIAR31 19:3 D. ot 0. LETTER OE TRANSMITTAL. U. S. Department of Agriculture, Office of Experiment Stations, WasMngton, D. C, June 20, 1907. Sir: I have the honor to transmit herewith and recommend for publication as Bulletin 193 of this Office, a report of investigations on the digestibility and nutritive value of meat, conducted by H. S. Grindley, professor of general chemistry in the college of science of the University of Illinois, Timothy Mojonnier, and Horace C. Porter, as a part of the cooperative nutrition investigations of this Office. The report includes the results of 67 natural and 99 artificial diges- tion experiments with meat, undertaken to determine the ease and thoroughness of digestion of different Idnds and cuts of meats cooked in a variety of ways. These studies form a part of the investigations which have been in progress at the University of Illinois from 1898 to 1907 to determine the effects of cooking upon the nutritive value of meat. The results reported are of widespread interest, as they show that meat of all sorts is to be classed among the very digestible foods, and that differences in kind, cut, or method of preparation for the table have less effect upon the ease or the thoroughness of digestion than has been frequently claimed. The editorial work in preparing the reports of these investigations for publication was done by R. D. Milner of this Office. Respectfidly, A. C. True, * Director. Hon. James Wilson, Secretary of Agriculture. (3) CONTENTS, Page. Introduction 5 Experiments on the thoroughness of digestion of meats 5 Work of other investigators 6 Investigations here reported 6 Experimental methods 7 Comjx isit inn of food materials 7 Composition of feces 10 Details of experiments with mixed diet, including meat 12 Experiments with amounts of food not restricted 12 Experiments with definite amounts of food and of uniform muscular exercise 15 Experiments with \arying amounts of food and of muscular exercise. . 19 Details of experiments with simple diet, including meat 24 Experiments with lean beef cooked in water for 1 hour 27 Experiments with lean beef cooked in water ior 2 hours 28 Experiments with lean beef cooked in water for 3 hours 30 Experiments with lean beef pan broiled 31 Experiments with lean beef fried 32 Experiments with lean beef roasted 32 Experiments with fat beef cooked in water for 2 hours 33 Experiments with beef ril:)s roasted 34 Experiments with fat veal leg roasted 36 ExperimtMits with mutton leg roasted 38 Experiments with pork roasted 39 Summary and discussion of results 40 Digestibility of the nitrogen (protein) as corrected for metaliolic products in the feces -17 Income and outgo of nitrogen and gain or loss of protein 52 Investigations on the ease or rapidity of digestion of meat 59 Examination of stomach contents 59 Artificial digestion experiments 61 Investigations here reported 63 Development of method '. 64 Tests of method adopted 72 Details of experiments on the ease of digestion of protein 76 Experiments with beef 78 Experiments with mutton 89 Experiments with pork 90 Summary and discussion of results '. 94 Conclusions - 99 (4) EFFECT OF COOKING UPON DIGESTION OF MEAT INTRODUCTION. Ill connection with the nutrition investigations of the Department of Agricuhure studies have been made at the University of Ilhnois, in cooperation with the Office of Experiment Stations, of the various factors which affect the nutritive vahie of meats. A part of this inquiry has been discussed in previous bulletins" of this Office, wliich report studies of the changes in the nature and propor- tions of the nutritive ingredients of the meat that are produced by cooking. ^Another part of the research is taken up in the present bulletin, which reports investigations on the effect of cooking upon the digestibility of the meat. Two Imes of work have been followed in these investigations. The more important concerns the thorough- ness with wliich different kinds and cuts of meats, cooked in different ways, may be digested by man in normal health — that is, the propor- tions of the nutrients of the meats that would be actually dissolved and absorbed during their passage through the alimentary canal. In addition to this, however, an attempt was made by means of artificial digest^'on experiments to gain some knowledge regarding the eft'ect of cooking in general, and different methods of cooking in particular, upon the ease or rapidity of the peptic digestion of the proteid of the meat. EXPERIMENTS ON THE THOROUGHNESS OF DIGESTION OF MEATS. The thoroughness with which a given food material may be digested can be studied satisfactorily only by means of natural digestion experiments in which the quantities of nutrients in the material eaten are determined and compared with those in the feces excreted. Such experiments are sometimes made with dogs and other animals, but the most satisfactory are those made with men. Only those made with men are here considered. oU. S. Dept. Agr., Office of Experiment Stations Buls. 102, 141, 162. (5) WORK OF OTHER INVESTIGATORS. A number of investigators have studied the thorouglmess of diges- tion of cooked meat. For example, Hofmami" compared the diges- tibihty of meat protein with that of vegetable foods. Rubner* studied the digestibility of roasted lean beef in connection with an extended study of the digestibility of single food materials. Atwater'^ studied the comparative digestibility of beef and fish, in an investiga- tion on the nutritive value of these two kinds of animal food. An experiment was made by Malfatti'' with roasted and boiled beef. Solntzev^ made experiments with canned beef and mutton and with similar meats freshly prepared and cooked in water at 85° C. ; and Smetski ' studied the asshnilation of the nitrogenous constituents of boiled salt meat. Solomin ^ investigated the digestibility of tripe. No attempt has been made to include here a complete summary of the work of this nature, for the reason that in general the results of experiments such as these do not throw much light on the c[uestion as to what effect different methods of cooking have upon the digesti- bility of the meat. C. Forster,'' however, has published the results of an extended studv of the digestibilitv of dift'erent cuts of beef cooked in different ways as compared with that of raw beef. These are considered in some detail on page 45, in a comparison with the results obtained in the investigations reported in the present bulletin. INVESTIGATIONS HERE REPORTED. In the present bulletin the results of 67 digestion experiments with men are given. These experiments were of two kinds. In 23 of them the meat was eaten in a rather varied ration, the purpose being to determine the effect of different methods of cooking meat upon the digestibility of an ordinary mixed diet, including meat, beef being the meat selected. In the remaining 44 experiments the meat was eaten in a very simple diet, the food materials other than meat being those the digestibility of which is fairly well established, so that by making due allowance for these the digestibility of the meat itself may be calculated. Of these, 31 experiments were ^^^th beef cooked in water for different lengths of time, and by roasting, trying, a Reported by Yoit in Sitzber. K. Bayer. Akad. Wiss. Math. Phys. Kl., 1869, Pt. 2, p. 483. ftZtschr. Biol., 15 (1879), pp. 121-125. cZtschr. Biol., 24 (1888), pp. 23-25. d Sitzber. K. Akad. Wiss. [Vienna]. Math. Xaturw. Kl.. 90 (1884), No. 3. p. 323. e Preserved Food for Armies. Inaug. Dis^., Univ. St. Petersb., 1886. pp. 94-98. /The Composition of Salt Meat and the Assimilation of its Nitrogenous Constituents. Inaug. Diss., Univ. St. Petersb., 1886. j/Arch. Hyg.. 27 (1896). p. 182. ADer Nahiwert des Ilindfleisches. Inaug. Diss., Univ. Berlin, 1897. and pan broiling; and 6 were mth veal, 3 with mutton, and 4 with pork, all roasted. The results of the experiments with beef show the effects of different methods of cooking upon the digestibility of the meat, and a comparison of the results with the various meats cooked in the same way shows the relative digestibility of different kinds of meat. In all the experiments with simple diet a study was made of the amounts of metabolic nitrogen in the feces, and in all the 67 experi- ments the urine was collected and the l)alance of income and outgo of nitrogen was determined. EXPERIMENTAL METHODS. The methods followed in these experiments were similar to those described in former bulletins of this Office; hence a brief statement wall suffice here. In general, the various food materialc were eaten ad libitum, the amount of each article eaten being recorded and a sample reserved for analysis. The feces for the total experimental period were collected and analyzed. The digestibility of the nutri- ents of the total diet was determined from the quantity of each in the food and in the feces. In the experiments with simple diets the digestibility of the nutrients of the meat alone was computed from the data for the total diet by allowing for the digestible nutrients of the materials eaten with the meat, as explained in the description of such experiments (p. 26). Aside from these general principles, however, the different groups of experiments recorded herein differed considerably in some details. Those details that pertain particularly to given experiments are therefore given in connection with the other data of the experiments. The different kinds of experiments included in the investigation are considered separately on the following pages. The data regarding composition of food material and feces for the natural digestion experiments are here tabulated. COMPOSITION OF FOOD MATERIALS. Samples of all the food materials used iri the experiments were analyzed according to the usual methods, with such minor modifica- tions as have been found expedient. Nitrogen was determined by the Kjeldahl method. Moisture was determined by heating the sam- ple for sixteen hours at 104° C. in a current of hydrogen. Ether extraction by the Soxhlet method was continued for twenty-four hours in the case of meat and baked beans, for sixteen to twenty hours in the case of bread, breakfast food, and bananas, and for about twelve hours in the case of milk. The results of the analyses are given in Table 1. 8 Table 1. — Composition of food materials in natural digestion experiments here recorded. Lab- ora- tory No. Food material. Used in experiment No. - Water. Protein (NX6.25). Fat. Carbo- hy- drates. Ash. Per ct. Per ct. Per ct. Per ct. Per ct. 610 Beef, round, pan broiled 267-270 66.59 26.08 3.14 3.82 613 do 267-270 66.60 26.31 3.04 3.87 716 Beef, round, cooked in water 2 hours. . 271,272 61. 86 29.07 6.10 3.46 718 do 271,272 61.64 28.98 6.07 3.30 739 Beef, round, cooked in water 4 hours . . 273,274 63. 92 25.97 7.52 2.73 740 do 273, 274 275 63. 77 56.98 26.15 35.71 7.56 4.97 2.74 783 Beef, round, cooked in water 2 hours . . 2.01 798 do 276 54.68 35.09 7.97 1.82 809 .do 277 278 279 280 53.73 64.12 64.83 62.30 36.13 26.64 26. 07 28.64 7.51 6.74 5.72 6.86 2.81 825 Beef, round, fried in butter 2.28 839 do 1.58 849 Beef, round, cooked in water 20 minutes . 1.67 861 do 281 282 283 284 285 286 287 288 289 291 293.294 295, 296 60.71 66.39 62.96 56.95 55.99 56.12 56.97 58.96 57.87 62. 10 67. 59 56.72 32.-61 23.24 27.97 31.52 31.64 33.84 34.37 32.18 35.06 30.16 26. 29 34.35 5.25 8.43 7.18 9.33 9.77 8.13 6.08 6.53 5.54 5.75 3.91 7.11 1.61 871 Beef, round, roasted 1.31 884 .. ..do 1.45 899 Beef, round, cooked in water. 2.16 925 do . . . 2.12 963 do 1.82 988 . ..do 3.40 1029 ....do 1.74 1054 do 2.08 1108 do . 2.15 1131 .do 1.76 114S do 1.71 1216 do 298. 299 64.86 30.76 2.47 1.62 1244 do 297-300,301 68.45 60. ()7 27.42 2. ,34 1.62 1116 do 291 33.80 4.07 2.21 1107 Beef, round, raw 291 75.20 19.21 4.76 1.00 1119 do 290-292 74.41 20. 84 3.71 1.05 1130 do... 293, 294 76. 54 20.68 1.97 1.07 1287 Beef, shoulder, cooked in water 368-370 49.39 22.61 26.46 1.60 1313 Beef, round, pan broiled 371-373 56. 98 28.46 12.24 2.58 133J Beef, round, : ried in lard ; . . . 374-37ti 52. 26 33.97 11.22 2.58 1347 Beef, round, roasted 377-379 .59. 12 29.77 8.30 3.20 1525 Beef, ribs, roasted 422,423 44.43 20.08 34.09 1.93 1561 do 426, 427 55.11 24.64 18.21 2.55 1595 do 428 49.88 20.56 28. 06 2.37 1617 do 429. 430 43.51 23.63 30.67 2.34 1400 Veal, leg, roasted 380-382,383 53.17 28. 12 16.56 2.34 1469 do 419.421 66.20 28.38 3. 34' 2. 47 1438 Mutton, leg, roasted 381.384,385 50. 58 25. 10 21.82 2.89 1447 do.... 381,384,385 52.05 29. 57 17.05 2.45 1452 Pork, fresh ham, roasted 386, 387 47.09 31.82 20. 04 2.26 1546 do 424 53.02 25. 13 20.24 2.37 15(iO do 425 54.65 26. 10 16.27 3.23 620 Butter 267, 268 8.67 .46 88.65 2.22 621 do 267,268 8.83 .70 88.39 2.08 656 do 269,270 8.55 .49 88.46 2.50 657 . ..do 269, 270 271,272 273,274 275 276 277 278 279 280 281 282 283 284,285 286. 287 288. 289 290,292 293, 294 2f>5, 296 7.75 9.03 8. 99 10.50 7.13 12.32 9.28 9.01 8.17 9.31 8.53 6.42 11.94 12.45 13. 37 6.94 6. 40 9.46 .48 .52 .56 .69 .80 .40 .38 .54 .60 .56 .64 .81 .55 .52 .56 .81 .6l' .60 89.58 88.42 88.47 86. 61 90.74 84.55 88.29 87.39 89.03 88.80 89.75 90.32 82.05 82.65 81.07 91. 70 92. 64 89.22 2.19 713 do 2.03 741 do 1.98 786 .. .do 2. 20 802 do . 1.33 813 do.. 2.73 828 .do 2.05 837 do . . . 3.06 852 do 2.20 864 do 1.33 874 .. ..do 1.08 885 do 2.45 902 Butter, creamery 5.46 964 do 4.38 1032 ....do 5.00 1123 do .55 1133 .do .34 1150 do .72 1208 do 297-301 11.42 .66 87.68 .24 1286 do 368 .371,374 377 382,383 384, 385 .386,387 420,421 422, 423 424. 425 426, 427 428 429. 4,30 267,268 6.82 8.75 7.69 13.61 12.81 11.72 9. 83 12. 73 10. 11 11.02 8.62 11.07 86.92 .(» .80 .47 .82 .79 .55 . ,55 .55 1.00 .70 .67 .82 3.21 89. 92 88.09 89. 45 82.69 83. 22 85. 62 88.00 84.35 87.80 85.90 88.33 86.09 4.34 "i'so" 2.66 1312 ■ do 2.36 1345 .do 2.39 1407 Butter 2.88 1436 do 3.18 1451 .do 2.11 1468 do 1.62 1526 do . .: 2.37 1549 do 1.09 1564 . ..do 2.38 1598 do 2.38 1620 .do 2.02 622 Milk .73 Table 1. — Composition of food materials in natural digestion experiments here recorded- Continued. Lab- ora- tory No. Food material. Used in experiment No.- Water. Protein (NX6.25). Fat. Carbo- hy- drates. Ash. 623 Milk 267, 268 269, 270 271,272 273,274 275 276 277 278 279 280 281 282 283 284 284,285 286 288 285 287 289 291 295,296 298, 299 300 29/, 300, 301 368-370 3ti9 371-373 374-376 377-379 380,382,383 3S0,382.383 381,384,385 386,387 419-421 422.423 424,425 426.427 428 429, 430 267,268 267,268 267,268 269,270 269, 270 271,272 271,272 273.274 273,274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291,292 293,294 295,296 297,298 299-301 368-370 371-373 374-376 377-379 380-383 381,384,385 386. 387 417,420,421 Per ct. 86.92 86.32 87.11 87.24 86.62 87.11 88.37 87.75 87.59 86.88 86.90 88.15 87.72 91.25 92.37 91.37 91.41 87.92 87.92 88.20 89.18 88.46 88.60 88.53 87.64 87.37 89.33 87.83 87.46 87.14 86.00 S7.69 87.81 87.67 87.13 86.02 87.84 87.30 87.29 87.44 • 41.31 37.78 44 81 39.02 39.39 39.37 40.20 38.80 38.80 44 19 44 20 44 37 41.59 42.55 42.00 41.42 44 84 42.53 43.41 44 17 44 15 45.04 43. 52 44 14 45.58 44 57 44 66 47.22 43.92 45.62 44 24 42.23 44 95 43.52 44 11 44 07 43.08 45.56 Per ct. 3.27 3.35 3.15 3.25 3.55 3.46 2.67 2.78 2.79 2.77 3.04 2.48 2.63 3.13 2.85 3.10 3.03 3.37 3.23 3.08 3.01 2.75 3.04 2.83 3.16 2.74 2.28 2.70 2.86 2.89 3.17 3.04 3.26 3.18 3.13 3.25 3.23 3.00 3.02 2.99 7.39 7.77 7.04 8.09 7.86 7.92 7.77 7.98 7.90 7.39 7.76 7.53 9.04 8.40 8.52 8. 06 8.30 8.76 8.26 8.12 8.3.1 8.24 8.76 8.48 7.47 7.89 ■7.76 7.28 7.46 7.20 8.61 9.34 9.31 9.41 9.05 9.08 9.15 8.01 Per ct. 4 37 4 64 4 11 3.80 4 33 4 36 3.37 3.57 4 21 4 36 4 74 3.84 3.83 .39 .42 .19 .10 3.68 3.76 3.65 2.94 3. GO 3.18 3.37 3.93 4 17 2. 79 4 31 4 25 4 16 5.35 3.86 3.69 3.83 4 41 5.71 3.87 442 4 16 4 20 3.01 3.14 2.70 2.48 2.47 2.35 2.42 3.46 3.34 .89 .48 1.36 1. 16 1.11 1.31 .88 .71 .85 .96 .72 .,56 .46 1.00 .70 .36 .38 .38 .16 .74 .74 .88 .54 .27 .59 .39 .41 .31 .40 Per ct. 4 80 4 94 4 90 4 99 4 74 4 31 4 84 • 5.16 4 70 5.27 4 60 4 86 5.13 4 49 3.70 4 62 4 71 4 29 4 38 4 33 4 18 4 52 4 48 4 61 4 58 5.04 4 93 450 460 5.06 4 76 4 74 4 51 4 49 4 61 4 37 4 34 4 58 4 87 4 69 47.13 50.10 44 34 49. 28 49.25 49.37 48.62 48.85 49.04 46.67 46.27 46.91 47.46 47.14 47.42 48.76 45.49 47.17 46.57 46.09 45.91 45.34 4a 69 4,5. 94 45.24 46.34 46.51 44 65 47.05 45.77 45.39 47.05 44 64 45.76 45.59 45.67 46.75 45.21 Per ct. 0.64 670 do .75 723 do. .73 746 ....do .72 789 do .76 an . . do .76 812 do .75 829 do .74 838 do . .71 853 . ..do .72 865 do .72 875 .do .69 886 do .69 898 Milk, skim .74 927 . do .66 985 do .72 1031 do .75 928 Milk , whole .74 990 do .71 1057 . do .74 1117 do .69 1151 .do .67 1209 . .do .70 1232 do .66 1234 .69 1285 .. ..do .68 1301 1311 1329 1346 1405 do do do do Milk .67 .66 .83 .75 .72 1429 do .67 1435 do .73 1449 do .83 1466 1523 do .. .do .72 .65 1547 do .72 1562 do . . . .70 1597 do .66 1619 do . .68 614 Bread. 1.17 616 do 1.21 617 do. . 1.11 652 do 1.13 655 do 1.04 710 .do.. . . .99 712 do .99 735 do .91 736 . .do .91 785 do .86 799 do.. 1.29 810 do .83 826 do .75 840 do .80 850 do .75 862 .do .88 872 do .66 882 do . . . .69 901 .80 924 do .89 962 do . . . 1.00 989 ....do .92 1030 do 1.03 1056 . ..do .74 1109 do 1.35 1122 .. .do.. .. .82 1132 do .69 1149 do . .89 1207 do .83 1233 do .... .67 1284 .88 1327 do ; .84 1328 1344 1404 1437 1450 1467 do do Bread do do do .83 .72 .86 .77 .71 .82 10 Table 1. — Composition of food materials in natural digestion experiments here recorded- Continued. Lab- ora- tory. No. 1524 1548 1563 15t){) 161S 60S 787 797 897 624 625 650 651 724 747 784 800 811 827 841 851 863 873 883 900 923 961 987 1028 1055 626 639 627 638 669 668 722 721 744 745 926 950 986 1026 1053 1088 609 609 788 896 Food m.-itcrial. Bread do do do do Breakfast food do RoUed oats Creiuii of wheat Beans, Itaked do do do do do do do do do do do do do do Beans, canned baked. do do do do do Bananas do do do do do do ; do do do do ....do ....do ....do do do Sugfl r do do do Used in experiment No. - Water. 422.423 424, 425 426, 427 428 429.430 207-274 275 ; 275-283 284-289 267,268 267,268 267-270 267-270 271,272 273,274 ' 275 i 276 277 ' 278 279 280 281 282, 283 284 285 286 287 288 289 267 267 268 268 270 269 271 272 274 273 284 285 286 287 288 289 267-274 280-283 275-279 284-289 Per ct. 43.57 43.97 43.27 44.31 41.99 9.93 11.88 8.82 12. 40 67.42 67.58 67.46 67.60 68. 86 69.44 66.69 66.07 66.17 66.03 66.97 67.34 65. 61 66. 22 (16. 51 70 25 70.30 69.68 67.34 67.07 67. 06 76. 71 77.58 76. 25 Protein (NX6.25), Fat. 77.96 7&35 76.44 76.98 77.62 77.76 79.32 77.80 7a 68 80.27 79.73 78.04 Per ct. 8.68 8.39 9.26 .8.39 8.60 11. 32 12. 54 14.51 11.62 7.61 7.59 7.-51 7.43 7.50 6.81 7.23 7.53 7.34 7.43 6. 6. 97 96 40 54 f^. 59 6. 56 6. 57 6.56 7.49 7.13 7.47 1.03 1.14 1.06 Per ct. .40 .23 .36 .38 .79 1.02 .94 7.24 1.10 2.33 2.24 2.15 2.36 2.21 2.30 1.39 .94 1.18 1.97 1.46 1.53 1.06 .95 1.21 2.04 1.84 2.04 1.15 1.50 1.46 .00 .07 • .07 Carbo- hy- drates. Ash. Per c>. 46.48 46.61 46.39 45.96 47.78 77.31 74.13 67.61 74. 43 20.17 20. 18 20.45 20. IS 19. 13 19. 84 22.19 22.95 22.61 22.06 21.91 ■ 22.03 23. 29 22. ,50 20. 96 19. 4(i 19. 69 19.58 21. 43 22. 43 21. 61 21. 43 20. 45 21.78 1.07 1.06 1.05 1.10 1. 19 1.19 .94 .89 1.01 1.03 .88 1.15 .03 .03 .05 .05 .05 .05 .09 .09 .09 .14 .11 .08 .35 .27 .04 20.11 19. 7(i 21. 70 21. 09 20.43 20. 28 18.92 20.48 19.47 17. 93 18.57 20. 02 100. 00 99. 65 Per ct. 0.87 .80 .72 .96 .84 .42 .51 1.82 .45 2.40 2.41 2. 42 2.44 2. 30 1.01 2.50 2.51 2.70 2.51 2.69 2. 15 2.04 2.79 2.73 1.69 1. 61 2.13 2.58 1.87 2.40 .78 .75 .84 .83 .80 . 77 .78 .71 .72 .-73 .74 . 75 .63 .71 .71 100.00 99. .53 COMPOSITION or FECES. Separation of the feces pertainir.fr to a oriven experiment was made by means of lampblack, taken in gelatin capsnles at the beginning and the end of the experimental period. The total quantity of feces for each experiment was dried and ground and the samples for analysis were weighed from the total material thus prepared. In the first 8 experiments the samples were analyzetl in the water-fi'ee condition, but in all the others thc}^ were in the air-dry condition, the methods of analysis being the same as in the case of the foods. Extraction with ether was continued for twenty-four hours, but it was difficult in some cases to get satisfactory results in this determination owing, 11 no doubt, to the fact that the feces contain substances other than fat which are sohible in ether. The data regarding the composition of the feces are given in Table 2. Table 2. — Composition of feces in the digestion experiments here reported. Lab- ora- tory No. 758 759 760 761 762 763 764 765 794 807 818 834 846 858 870 880 891 991 992 993 994 1089 1090 1115 1128 1129 1138 1139 1156 1157 1223 1227 1231 1248 1252 1291 1295 1299 1318 1322 1.326 1335 1339 1343 1352 1356 1360 1411 1415 1419 1423 1442 1446 1456 1460 1473 1477 1481 1530 1534 1553 1557 1568 1572 1602 1624 1628 Material. Feces, water-free. do do do do do do,. do Feces, air-dried . . do From ex- periment No.— -do. .do. .do. .do. .do. -do. .do. .do. -do. .do. .do. .do. .do. .do. .do. .do. .do. .do. .do. .do. .do. .do. .do. .do. .do. .do. .do. .do. .do. .do. .do. .do. .do. .do. .do. .do. .do. .do. .do. .do. .do. .do. .do. .do. .do. .do. .do. .do. .do. .do. .do. .do. .do. .do. -do. .do. .do. 267 269 271 273 268 270 .272 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 291 290 292 293 294 295 296 297 298 299 300 301 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 419 420 421 422 423 424 425 426 427 428 429 430 Per cent. Water. Protein (N.X 6.25). Fat. 6.21 6.62 7.26 7.05 7.71 6.67 7.46 8.53 9.12 8.36 10.83 9.47 9.05 9.00 10. .55 6.82 10. 48 8.42 9.59 6.89 7.12 7.30 8.40 12.20 7.47 16.19 14.23 9.08 15.39 13.82 8.46 12.71 7.90 8.75 11.87 8.27 9.85 13.64 8.63 11.62 12.90 10.33 6.98 1.3.30 4.63 7.95 6.06 8.66 7.33 6.52 8.87 6.95 8.63 7.75 6.64 7.91 9.13 7.83 8.681' Per cent. 34.71 34.63 34.08 34. 30 25.83 26.53 27.82 36.94 .37. 77 39.20 36.30 37.13 37.12 37.74 40.46 41. 37 43.00 36. 98 34.72 39.00 .38. 25 38.88 36. 86 28.00 ."^9. 51 .33. 98 38. 82 26.04 28.24 27.55 27.42 29. 26 22.49 28.20 29.78 24.64 27.67 30. 15 29.99 34. 95 27.42 28.50 30.40 21.02 28.47 30.86 22.76 40.41 32.03 38.12 28.81 30.57 21'. 32 32.23 23.82 33.45 24.92 21.97 21.23 18.12 29.95 30.98 17.84 24.91 26.23 29.60 35.27 Carbo- hydrates. Ash. Per cent. 14.17 13.15 13.19 13.66 7.71 11.14 9.81 10.28 10.71 9.30 12. 21 7.87 10.27 10.12 11.44 12.41 11.25 7.15 10.29 7.42 7.77 7.76 6.80 12. 32 10. 96 13. 83 8.67 11.60 12.05 15.46 12.28 9.15 9.25 17.05 10.72 13.22 23. 86 22.16 8.47 8.87 10.87 6.93 9.03 6.55 5. 76 7.59 6.26 8.81 8.73 9.56 9.70 9.49 9.92 11.07 8.36 11.81 11.64 10.35 12.30 10.69 10.76 9.37 7.56 9.92 10.25 10.07 10.52 Per cent. 36. 29 37.82 38.81 36.70 45.99 42.88 42.53 41.64 28.00 27.68 26.61 29.54 27.59 27.77 23. 52 21.51 21.09 28.07 26.91 25.22 28.34 26.80 30.09 38. 05 28.55 28.43 32. 37 38.64 38.73 29.30 28.59 16.49 38. 37 6.66 23.77 33.66 8.63 21.23 28.92 14.21 30. 23 29.91 18.05 37.82 20.96 15.39 35.97 21.81 31.04 27.92 36.80 32. 42 45.77 28.45 41. 39 18. 03 38.43 40.95 41.08 45.64 32.15 30.23 48.44 38.26 39.31 36.63 i 27.70 1 Per cent. 14.83 14.40 13.92 15.34 20.48 19.45 19.84 21.13 17.31 17.20 17.62 18.41 17.31 17.70 17.12 16.18 1.5. 54 19.44 17.25 18.89 16.59 17.56 15.70 14.81 10.50 15. 34 10.55 16.83 13.86 20. 39 23. 31 .•^2. 90 21.92 31.90 21.50 19.40 24.45 12.64 24.16 29.26 23.58 25.91 30.65 26.34 24.96 32.52 26. 38 17. 35 15.30 14.07 17.71 14.22 18.36 20. .?0 20.37 28.05 17.68 20.21 16.52 18.60 18.51 21.67 19.52 19.00 15.08 15.87 17.83 12 DETAILS OF EXPERIMENTS WITH MIXED DIET, INCLUDING MEAT. As previously suggested, one of the objects of the digestion experi- ments here reported was to determine what influence different meth- ods of cooking meat would have upon the digestibility of the total diet in which the meat was eaten. For this purpose 23 experiments were made in connection with the investigations conducted durinsr 1898-1901 in wliich meat cooked in different ways constituted part of a mixed diet that included several common food materials. In selecting a diet for these experiments the problem was to obtain a ration containing such a variety of food materials that it would fairly represent an average mixed diet and be sufRciently palatable to be eaten for several days, but which should not include so many different kinds of food that the number of analyses would be unduly large. The foods selected were bread, butter, sugar, milk, rolled oats or wheat breakfast food, beans, and bananas, in addition to the meat. The diet made up of these materials proved quite satisfactory for all four subjects throughout all the tests. The 23 experiments here considered wer^ all alike in that the diet consisted of the same kinds of food materials, but they differed some- what in respect to the control of the quantity of food eaten and of the muscular activity of the subjects, and so the experiments have been arranged in three groups, in accordance with these variations. EXPERIMENTS WITH AMOUNTS OF FOOD NOT RESTRICTED. This group includes 8 experiments. The subjects were two young men, designated as A and B. Subject A was 35 years old and weighed, in ordinary clothing, about 170 pounds; subject B was 23 years old and weighed about 135 pounds. They were both in good health, had good appetites and apparently normal digestion. Both were chemists, and during the time of the experiments were engaged in their ordinary duties in the laboratory. Four experiments were made with each subject, in each case the corresponding experiments with the two subjects being carried on simultaneously. The daily food in the experiments consisted of a mixed diet of the materials mentioned above. The food materials were obtained as needed, and from each fresh portion a sample was reserved for analysis. The same kind and cut of meat, beef round, was used in every case, but it was differently cooked, as explained below. No attempt was made to regulate the quantities consumed, the subjects being allowed to eat at each meal according to their desires for the selected foods. There were noticeable differences in the amounts of the different foods eaten by the two subjects in corresponding (experi- ments and by the same subject in different experiments. Experiment No. 267, with subject A, and No. 268, with subject B, began with breakfast July 5, 1899, and continued four days (12 13 meals). Without any intermission between the two periods experi- ment No. 269, with subject A, and No. 270, with subject B, began with breakfast July 9, 1899, and continued three days (9 meals). The meat eaten in each experiment was beef round pan broiled (fried without added fat) for fifteen minutes. Experiments Nos. 271 and 272, with subjects A and B, respectively, began with breakfast July 19, 1899, and continued four days (12 meals). In cooking the meat eaten in these two experiments it was placed in boiling water, and the temperature of the water was then maintained at 80° C. for two hours. Experiments Nos, 273 and 274, with subjects A and B, respectively, began with breakfast July 26, 1899, and continued four days (12 meals). The meat in this case was placed in cold water, which was then heated and maintained at 65° to 70° C. for four hours. The data regarding the digestibility of the diets in these experi- ments are siven in Table 3. Table 3. — Results of digestion experiments Nos. 267-274 Labo- ratory No. Weight of mate- rial. Total or- ganic matter. Protein (NX6.25). Fat. Carbo- hydrates. Ash. 609 Experiment No. S67, subject A. Sugar Butter Milk [■Bread >Baked beans Grams. 220 220 1,633 715 895 1,200 140 360 Grams. 220 196 202 411 269 265 125 106 Grams. Grams. Grams. 220 Grams. 620, 621 1 53 53 68 13 16 95 i95 71 21 20 1 1 11 5 622, 623 614,616, 617 624,625, 78 337 181 251 108 11 8 22 650, 651 626,639 608 Bananas Breakfast food 9 1 610-613 Meat Total diet 14 5,383 77 1,796 65 299 27 320 11 1,175 28 70 758 Feces Amount digested 11 1,731 96 272 91 309 96 1,147 98 59 Per cent digested ,L - . 84 Experiment No. "268. subject B. Sugar Butter Milk. [•Bread >Baked beans 609 60 240 4.916 585 761 1,200 140 410 60 213 609 336 228 270 125 121 60 620,621 1 159 43 57 13 16 108 212 214 17 17 1 1 13 5 622,623 614,616, 617 624,625, 236 276 154 256 108 34 7 18 650, 651 627,638 608 Bananas Breakfast food 10 1 610-613 Meat 16 Total diet 8,312 109 1.962 86 , 397 28 475 8 1.090 50 91 762 Feces 22 Amount digested 1,876 96 369 93 467 98 1,040 95 69 Per cent digested 75 Experiment No. 269. .subject A . Sugar 609 160 165 1,175 525 600 850 105 260 160 148 152 313 180 177 94 77 160 58' 259 122 168 81 656, 657 Butter 1 39 41 45 9 12 69 i47 55 13 13 i' 8 4 670 Milk 9 652,655 Bread 6 650,651 Baked beans 14 668 Bananas 9 608 Breakfast food 610-613 Meat 10 Total diet 3,840 53 1,301 46 216 1.8 237 7 848 20 52 759 Feces 8 Amount digested 1,255 96 198 92 230 97 828 97 44 Per cent digested 85 . — 14 Table 3. — Results of digestion experiments Nos. ^67-'£74 — ("ontinued. Labo- ratory No. Weight of mate- rial. Total or- ganic matter. Protein (NX6.25). Fat. Carbo- hydrates. Ash. 609 Experiment No. g70. Sugar Butter Milk Broad Baked beans subject B. _ Grams. 45 180 3,716 450 500 850 105 300 Orams. 45 161 479 269 150 180 94 88 Grams. 1 1 Grams. Grams. 45 i83' 222 102 171 81 Grams. 656,657 670 6.52.6.55 650,651 1 124 36 37 9 12 79 160 172 11 11 r 9 4 28 5 12 660 Bananas .... 7 60S Breakfast food 610-613 Meat 12 Total diet 6.146 77 1,466 62 298 20 364 i 9 804 33 68 763 Feces 15 Amount digeste Per cent diirestoc d 1,404 96 278 93 355 98 771 96 53 78 Kxperiment Xo. 371. Sugar Butter Milk Bread Baked l)eans .^ubjerf .1 . 609 240 220 l.,500 700 960 1 . 400 140 400 240 195 182 413 277 320 125 140 240 713 ■ 1 47 55 72 15 16 116 194 62 17 21 1 1 24 4 723 710.712 724 722 73 341 184 304 108 11 7 22 11 608 Breakfast food 1 716-718 Meat Total diet 14 5.. 560 78 1.892 67 322 V 27 320 10 1,250 30 70 760 Feces Amount digested Per cent digested 11 1,825 96 295 92 310 97. 1,220 98 59 84 Experiment Xo. 273, Sugar Butter Milk subject B. 609 713 723 t;o 180 4.800 5(50 800 1.400 140 440 liO UiO .->S3 330 231 311 125 155 i' 151 44 60 15 16 128 "'. '159' 197 13 18 1 1 27 60 235' 273 153 295 108 4 35 710.712 724 721 608 Baked Iteans Bananas Breakfast food 5 18 11 1 716,718 Meat Total diet 15 8,380 70 1,956 56 415 20 416 7 1,124 30 89 764 Feces Amount digested Per cent digestec . 14 1.899 97 395 95 409 98 1,094 97 75 84 'Experiment Xo. 37.^. Sugar Butter Milk subject A 609 741 24 220 .1.500 710 960 1.400 140 400 24 19(i 181 428 277 302 125 134 r -49 .56 65 17 16 104 195' 57 24 22 "l 1 30 24 4 746 75 348 190 284 108 11 735, 736 747 Bread Bakod lipans 6 16 745 BjHiiinas 10 608 Brea.kfast food 1 739. 740 Meat 11 Total diet . . . 5.354 51 1.667 43 308 17 330 7 1,029 19 .59 761 ' Feces .\mount digested Per cent digesteii 8 1.624 •97 291 94 323 98 1.010 98 51 87 Experiment No. 374 Sugar Butter Milk subject B. 609 60 180 4.800 560 800 1.400 140 440 60 160 578 338 231 304 125 147 60 239' 274 159 286 108 741 746 1 156 45 54 17 16 114 159 183 19 18 1 1 33 4 34 735, 736 747 Bread Baked beans 5 1 13 744 608 Bananas Breakfast food 10 1 739, 740 Meat Total diet 12 8.380 63 1.943 49 403 17 414 6 1.126 26 79 765 Feces Amount digested 1 Per cent digested 13 1 1 1 1,895 97 i 386 96 1 408 98 1 1.100 98 66 83 15 The results of the foregoing experiments are summarized in Table 4. Table 4. — Summary of results of digestion experiments Nos. 267-274- Ex- Sub- ject. Diet. Total organic matter. Coefficients of digestibility. peri- ment No. Protein. Fat. Carbo- hydrates. Ash. 267 ■^69 A A B B A B A B Mixed diet, meat pan broiled do Per cent. 96 96 Per cent. 91 92 Per cent. 97 97 Per cent. 98 97 Per cent. 84 85 Averasfe 96 91 97 97 85 Mixed diot meat Dan broiled 968 96 96 93 93 98 98 95 96 75 270 do 78 Averasre 96 93 98 95 77 Average 4 experiments with A and B 96 92 97 96 81 Mixed diet, meat cooked In water at 80° C 271 96 97 92 95 97 98 98 L 97 84 272 do 84 Average. r 96 93 97 1 97 84 Mixed diet, meat cooked in water at 65-70° C 273 97 97 94 96 98 j 98 98 98 87 274 do : Average 83 97 95 98 98 85 There was striking uniformity in the digestibility of the total organic matter of the diets containing beef cooked in diiferent ways. In five experiments it was 96 per cent, and in three it was 97 per cent, showing that the diet as a whole was quite thoroughly digested in each case. In respect to the different nutrients also, the digestion of each was thorough and the agreement of results in the various experiments was satisfactory indeed. The indications are that under the conditions of these experiments the different methods of cooking the meat had no influence upon the digestibility of the diet as a whole. Possibly the amount of meat eaten was too small in proportion to that of the other materials to have much influence on the whole diet, though it will be noticed that in the majority of the experiments it furnished about a third of the total protein of the diet. EXPERIMENTS WITH DEFINITE AMOUNTS OF FOOD AND OF UNIFORM t MUSCULAR EXERCISE. In these experiments the attempt was made to control the condi- tions in such manner that, as nearly as possible, the only variation between the different experiments was in the method of cooking the meat. The same subject served throughout the whole series, and, except that the meat used was cooked in different ways, all the details, such as kinds and quantities of food consumed, daily routine of the subject, amount of exercise taken, etc., which it was believed might have some influence upon the general results, were maintained as 4663— Bull. 193—07 2 16 uniform as possible in the different experiments. It seemed fair to assume that under such conditions whatever differences were found in the results of the experiments would be due in large part to varia- tions in digestibility of the meat brought about by different methods of cooking. The subject in these experiments was a young man in good health and with apparently normal digestion. He was a chemist, and was engaged in his ordinary duties in the laboratory, but kept his work as nearly as he could the same from day to day, and in addition he took a given amount of physical exercise regularly each day during an experiment. His weight in ordinary clothing was about 1 36 pounds. Nine experiments were made, each of four days' (12 meals) duration. There was in each case a period of several da^^s between the end of one experiment and the beginning of the next. The chief purpose of the first experiment, which was considered as preliminary to the series, was to allow the subject opportunity to decitle what kinds and quantities of food materials were most agreeable. The diet selected consisted of meat, bread, butter, sugar, beans, rolled oats, and milk. The meat used in all the experiments was lean beef round, cooked in different waj^s, as explained below. When eaten it was seasoned with salt and pepper. The same amount of each food material was eaten in all the experi- ments in the series proper. The diet in the preliminary test differs slightly from that in the others, the quantit}' of beans being a little larger and that of bread a little smaller, while wheat breakfast food was eaten in place of rolled oats. The actual difference in the diet was so small, however, that the results of this test may be taken into account with those of the remaining experiments. As during the preceding experiments, the food materials were obtained as wanted in each test and sampled when used. The preliminary experiment, No. 275, began with breakfast Decem- ber 2] , 1899. In cooking the meat used it was placed in boiling water, and the temperature of the water was then kept at 80° C. for two hours. Experiment No. 276 began with breakfast Januar}^ 3, 1900. The meat used was cooked in the same way as in experiment No. 275. Experiment No. 277, which was a duplicate of No. 276, began with breakfast January 23, 1900. Experiment No. 278 began with breakfast February 20, 1 900. The meat used in this test was passed three times through a sausage mill, then made into balls and cooked by frying about ten minutes in a little melted butter, until medium well done. Experiment No. 279, whicli was a duplicate of experiment No. 278, began with breakfast March 12, 1900. Experiment No. 280 began with l)reakfast March 26, 1900. The meat used was placed in boiling water and then cooked twenty 17 minutes at 80° C. The cooked beef was ]mcj and undercione, but toiia^b. Experiment No. 281, a duplicate of No. 280, began with break- fast April 9, 1900. Experiment No. 282 began with breakfast April 23, 1900. The meat used was cooked by roasting or broiling a large piece, first sear- ing the surface for two or three minutes, then cooking for about twenty minutes, until medium well done. Experiment No. 283, a duplicate of No. 282, began with breakfast May 8, 1900. The data of these experiments are given in Table 5. Table 5. — Results of digestion experiments Nos. 275-283. Lab- ora- tory No". Weight of mate- rial. Total organic matter. Protein (NX6.25). Fat. Carbohy- drates. Ash. 788 Experiment No. 275. Sugar . . Grams. 120 180 2,486 140 880 780 400 Grams. 120 157 314 123 271 428 163 Grams. Grams. Grams. 120 Grams. 786 Butter 1 88 18 64 57 143 1.56 108 1 12 7 20 4 789 Milk 118 104 195 364 19 787 Breakfast food 1 784 Beans. . 22 785 B read 6 783 Beef Total diet 8 4,986 58 1,.576 44 371 22 304 6 901 16 60 794 Feces (air dried) Amount digested Per cent digested Experiment No. 276. Sugar 10 1,532 97 349 94 298 98 885 98 50 S3 788 120 180 2,486 140 840 840 400 8 120 165 301 125 263 458 172 120 107' 95 192 389 802 Butter 2 86 20 63 65 140 163 ins 10 8 4 2 801 Milk 19 797 Rolled oats .? 800 Beans 21 799 B read 11 798 Beef 7 Salt 8 Total diet. . 1 5,014 76 1,604 58 376 30 325 7 903 21 71 807 Feces 13 Amount digested 1,546 96 346 92 318 98 882 98 .58 Per cent digested 81 Experiment No. 277. Sugar 788 120 180 2,484 140 840 840 400 7 120 1.53 270 125 261 467 175 120 81.3 Butter 1 66 20 61 63 145 152 84 10 10 11 . 30 5 812 Milk ^ 120 95 190 393 18 , 797 Rolled oats. . . 3 811 Beans 23 810 7 809 Beef 11 Salt 7 Total diet 5,011 43 1,571 32 356 '16 297 5 918 11 74 818 Feces g .\mount digested 1,.539 98 340 96 292 98 907 99 66 90 Experiment No. 278. Sugar 788 120 180 2,484 140 840 840 400 9 120 160 2&5 125 264 485 134 120 828 Butter 1 68 20 62 76 107 159 89 10 17 10 27 4 829 Milk 128 95 185 399 18 797 Rolled oats. . . 3 827 Beans 21 826 Bread 6 825 Beef • 9 Salt 9 Total diet 5.013 34 1,573 26 334 13 312 3 927 10- 70 834 Feces 5 Amount digested 1,547 98 321 96 .307 99 917 99 65 Per cent digested 93 : 18 Table 5. — Results of digestion experiments Nos. 215-28S — ContiiiiuHl. Lab- ora- tory No. Weight of mate- rial. Total organic matter. Protein (NX6.25). Fat. Carbohy- drates. Ash. 788 Experiment No. 279. Suerar Grams. 120 180 2.480 140 840 840 400 Grams. 120 158 295 125 255 476 127 Grams. Grams. Grams. 120 ii7' 95 184 396 Grams. 837 Butter 1 73 20 59 71 104 157 105 10 12 9 23 5 838 Milk 17 797 Rolled oats. 3 841 840 839 Beans Bread Beef Salt Total diet 23 7 6 9 i 5.009 27 1,556 21 328 10 316 , 3 912 9 70 846 Feces Amount digested Per cent digested 5 1,535 98 318 97 313 ' 99 903 99 65 93 Experiment No. 280. Sugar Butter Milk Rolled oats 609 120 180 2,482 140 840 840 400 8 120 161 296 125 256 480 142 120 852 1 69 20 58 72 115 160 108 10 13 11 27 4 853 797 121 95 185 398 18 3 851 850 849 Bread Beef Salt Total diet 18 6 6 8 5,009 49 1,583 37 » 335 - 18 329 5 919 14 63 858 Feces 9 1.546 98 317 94 324 98 905 98 54 Per cent digested Experiment No. 281. Sugar Butter Milk. 86 609 120 180 2,480 140 840 840 400 7 120 161 307 125 494 485 151 120 864 1 75 20 62 68 130 160 118 10 9 21 9 865 114 95 423 410 18 797 Rolled oats. .. . . .. . 3 863 Beans 22 862 B rea d 7 861 Beef Salt Total diet 6 7 5,007 27 1,843 20 356 11 325 3 1,162 6 65 870 Feces 5 Amount digested 1.823 99 345 97 322 99 1,156 99 60 Per cent digested 93 Experiment No. 282. Sugar . 609 120 180 2,478 140 840 840 400 8 120 163 277 125 260 458 127 120 874 Butter 1 62 20 63 70 93 162 95 10 8 6 34 2 875 Milk 120 95 189 382 17 797 Rolled oats 3 873 Beans 23 872 Bread. 6 871 Beef Salt Total diet 5 8 5,006 50 1,530 38 309 21 315 6 906 11 64 880 Feces -Vmount digested . 8 1,492 97 288 93 309 98 895 99 56 Per cent digested 87 Experiment No. 283. Sugar ... 609 120 180 2,482 140 840 840 400 H 120 164 287 125 260 479 141 120 885 Butter Milk Rolled oats 1 65 20 74 76 112 163 95 10 10 7 29 4 886 797 127 95 176 396 17 3 883 882 884 Beans Bread Beef Salt Total diet 23 6 (> 11 5.013 49 1,576 37 348 21 314 (i 914 10 70 891 Feces 8 Amount digested 1,539 98 327 94 308 98 904 99 62 Per cent digested 89 19 The results of this series of experiments, including the preliminary test, are summarized in Table 6. Table 6. — Summary of result >< of duifstion experivwnts Nos. 275-283. Ex- Diet. Total organic matter. CoeiBcients of digestibility. peri- ment No. Protein. Fat. Carbohy- drates. Ash. 275 276 Mixed diet, meat cooked in water, well done, .do Per cent. 97 96 98 Per cent. 94 92 96 Per cent. 98 98 98 Per cent. 98 98 99 Per cent. 83 81 277 do 90 Average Mixed diet, meat coolred in water, underdone do 97 94 98 98 85 280 281 98 99 94 97 98 99 98 99 86 93 A verage 98 96 99 99 90 Mixed diet, meat chopped and fried 278 98 98 96 97 99 99 99 99 93 . 279 do Average Mixed diet, meat roasted 93 98 96 99 99 93 282 97 98 97 93 94 98 98 99 99 87 283 do Average 89 93 98 99 88 As in the previous series, the diet as a whole in these experiments was uniformly cjuite thoroughl}^ digested; and whether individual experiments or averages are considered, the variations in the results for the difl'erent nutrients are insignificant. The indications are that wdth this subject, under the conditions of the experiments, which though controlled were believed to be normal, differences in the method of cooking the meat had no effect upon the thoroughness of digestion of the diet in which it was eaten. EXPERIMENTS WITH VARYING AMOUNTS OF FOOD AND OF MUSCULAR EXERCISE. In the experiments of the preceding series the conditions in each case, even including the muscular activity of the subject, were main- tained as nearly as possible the same as in all the others, with the exception of the one, the effect of the variation of wliich it was desired to investigate, namely, the method of cookiiig the meat. In the fol- lowing experiments an attempt was made to learn whether variation in the amount of muscular exercise would have any effect upon the digestibility of the diet. The data are here given as 6 digestion experiments. There were, however, in reality 3 experiments, each of wliich was divided into two consecutive periods, in which the conditions were the same except that in the first period the subject abstained as entirely as possible from exercise of any kind, whereas in the second period he performed a con- siderable amount of muscular work. The diet in both periods con- 20 sisted of the same kinds of food materials, except that skimmed milk was used in some periods and whole milk in others. The amounts of the dilferent materials used in the two periods were so regulated that the quantity of protein per day was practically the same in the second period as in the first, but the quantity of energy was increased because of the work performed. Each of the 6 experiments continued four days (12 meals), except that No. 286 continued four and one-tliird days (13 meals). The sub- ject in all the experiments was a university student (C. A. S.), 21 years old, weighing without clothing a little over 140 pounds. The food consisted of a mixed diet containing meat cooked in every case by ])lacing it in boiling water and then maintaining the temperature of the water at 80° to 85° C. for two hours. Instead of obtaining the food materials as wanted — as was done in the previous experiments — most of them were prepared at the beginning of each pair of experiments in quantities sufficient to last throughout both periods. Preparation of food. — In all the experiments the meat used w'as the best beef round, cooked in water as stated above. In preparing it for consumption the cooked meat was removed from the water, and after draining and cooling was ground in a sausage mill, in order that a rep- resentative sample might be obtained for analysis. The ground meat \vas then seasoned with salt and pepper, and passed t\dce more through the sausage mill, after which it was put immediately into glass jars, sterilized for one hour at 95° C, and placed in a refrigerator until needed. The sample for analysis was taken while the meat was being put into the jars; tliis was dried in a water bath at 70° to 90° C. for about forty-eight hours, and then exposed as usual to room tempera- ture and moist lu-e before weigliing again. When w^eighed the sample was finely ground for analysis. The bread used in the experiments (known locally as "Cream White ") was broken into fragments and sealed in tared glass fruit jars, weighed, sterilized at 95° C. for one hour and then placed in a refrigera- tor until wanted. The crust of the loaf was removed and only the crumb was used, as it w^as hoped thereb}^ to get a more uniform and representative sample for analysis. The sample was taken at the time the pieces of bread were put into the jars, and was prepared for analy- sis in the same manner as the meat described above. Creamery butter, purchased from one of the local grocers, was used. It was made into 1 -ounce pats, wliich were put upon plates to drain and kept in the refrigerator over night; one half of each pat was removed, and all these were mixed into a composite sample for analysis; the remaining portions of the pats were placed in small glass jars, w^eighed, and kept in the refrigerator until used. The mixed milk of a considerable number of cows was delivered from the University dairv as needed. The milk was found to be 21 always so well mixed that it was necessary to analyze only one sample for each experiment. Sugar and wheat breakfast food (one of the common commercial sorts) were w^eighed from a bulk of each as needed. The wheat brealvfast food for each meal was cooked by steaming. The bananas used were bought each day as needed. One-half of each banana used was placed in a glass jar containing a little forma- lin, and at the end of the experiment the whole composite sample thus formed was thoroughly mixed by grinding in a mortar. A large portion of the mixed mass was dried and ground for analysis. Canned baked beans were used, the contents of a number of cans being thoroughl}" mixed, then sealed in glass jars, and sterilized for one hour at 95° C. The jars were then placed in a refrigerator and kept until used. A sample for analysis was reserved from the mixed mass as it was being put into the jars. This was prepared in the same manner as the sample of meat described above. The sterilized foods were preserved in good condition in the refrig- 'erator, and the subject selected the weighed jars as he needed them. The meat was warmed before using by steaming for fifteen minutes. The milk also was sometimes heated to 40° to 50°, according to taste. If any food remained in a jar at the close of the experiment it w^as weighed again and the amount deducted from the total. It was believed that to prepare the foods in the manner described gave better results than to w^eigli the food as needed from time to time, since errors in weighing that would result from loss of water occurring when food materials are kept exposed to the air would be prevented. Furthermore, it reduced the number of analyses con- siderably. Separation of feces. — The supper preceding the first meal of the first experiment and the breakfast following the last meal of the second experiment of each pair consisted of milk, with occasionally a little bread and butter, and with each of these meals lampblack in a gelatin capsule w^as taken. This gave blackened feces of a characteristic consistency preceding and following the feces pertaining to the experimental diet. It was assumed that none 'of the feces colored by the lampblack taken at these periods would pertain to the experi- mental diet. For separating the feces for"the first period from those for the second, the lampblack was taken after supper of the last meal of the first period. The urine in these experiments was collected in 6-hour periods, beginning with 7 o'clock on the morning of the first day of each experiment. Experiment No. 284 began w^th breakfast July 7, 1900. For the four days of this period the subject refrained as completely as prac- ticable from muscular exertion of any sort. Without intermission 22 experiment No. 285 began with breakfast July 11, 1900. During this period the subject was engaged for eight hours each day riding a bicycle over paved streets. The work involved in this exercise was liarder than that to which he had previously been accustomed. Experiment No. 286 began with breakfast July 21, 1900. The subject remained as quiet as practicable during the period. Experi- ment No. 287, following No. 286 without intermission, began with dinner July 25, 1900. The subject worked eight hours each day on a stationary bicycle. This work seemed to be even harder for him than that performed in experiment No. 285. Experiment No. 288 began with breakfast August 4, 1900. The subject did no actual work, but remained as quiet as practicable. In experiment No. 289, which began with breakfast August 8, 1900, the subject was at work eight hours each day on the stationary bic3xle. The work diu'ing this period did not seem as hard for him as that performed in experiment No. 2S7. The data of these six experiments are given in Table 7. Table 7. — Results of digestion experiments N OS. 284-289. Lab- ora- tory No. Weight of mate- rial. Total organic matter. Protein (NX0.25). Fat. Carbohy- drates. Ash. 896 Experiment No. 284- Sugar Butter Skim milk. Grams. 80 120 5,805 822 640 380 1,200 280 700 Gram.<<. 80 99 465 57 357 155 . 239 244 196 Grams. Grams. Grams. 80 Grams. 902 1 182 23 53 120 11 33 46 98 23 4 6 35 1 3 14 898 260 30 298 43 027 901 do B read 5 5 899 Moat 8 926 897 Bananas Breakfast food 227 208 136 9 1 900 Baked beans 12 Total diet. 10,027 126 1,892 91 469 47 184 9 1,239 35 90 991 Feces 25 Amount digested 1,801 95 422 90 175 95 1,204 97 65 Per cent digested 73 Experiment No. 285. Sugar 896 160 200 3,418 140 820 540 1,600 280 900 159 165 388 10 450 224 343 244 253 159 902 Butter 1 115 4 66 171 14 33 59 164 126 1 6 53 1 3 17 11 928 Whole milk . . . 147 5 378 25 927 Skim milk 1 924 Bread 7 925 Meat 12 950 Bananas . 328 208 177 12 897 Breakfast food 1 923 Baked bea ns 15 Total diet 8,058 86 2,236 62 463 30 371 9 1,402 23 84 992 Feces 15 Amount digested 2,174 97 43? 93 362 98 1,379 98 69 Per cent digested 82 Experiment No. 286. Sugar 896 90 130 7,190 690 405 1,350 320 700 90 108 569 379 170 278 279 197 1 90 964 Butter 1 223 58 137 14 37 46 107 14 4 33 1 4 14 6 985 Skim milk 332 317 .52 962 B read . 7 963 Meat 1 986 263 238 137 ;o 897 Breakfa st food 1 961 15 Total diet. 10,875 109 2,070 79 516 43 177 8 1,377 28 98 093 21 1,991 96 473 92 169 95 1,349 98 77 P(*r cent digested 79 23 Table 7. — Results of digestion experiments Nos. 284-289 — Continuod. Lab- ora- tory. No. Weight of mate- rial. Total organic matter. Protein. (NX6.25). Fat. Carbohy- drates. Ash. 896 Experiment No. 287. Sugar Grams. 160 200 5,069 780 420 1,600 280 800 Grams 1.59 166 576 422 170 306 244 241 Grams. Grams. Grams. 159 Grams. 964 Butter 1 164 64 144 17 33 60 165 190 4 26 2 3 9 9 990 Whole milk 222 354 36 989 Bread 7 988 Meat 14 1026 Bananas 287 208 171 10 897 Breakfast food . ... . 1 987 Baked beans 21 Total diet 9,309 128 2,284 95 483 49 399 10 1,402 36 98 994 Feces 21 Amount digested 2,189 96 434 <>0 389 97 1,366 97 77 Per cent digested 78 Experiment No. 288. Sugar . . ,S96 80 120 4,982 640 380 1,200 280 700 80 98 391 354 147 235 244 217 80 10.32 Butter 15l 56 122 11 33 50 97 5 6 2;, "l 3 10 Q 1031 Skim milk 235 292 208 157 37 1030 B read 1029 Meat 1053 Bananas s 897 Breakfast food 1 1028 Baked beans ... I? Total diet 8,382 94 1,766 69 424 37 147 7 1,195 25 79 1089 17 Amount digested . . . 1,697 96 387 91 140 95 1,170 98 62 Per cent digested 79 Experiment No. 289. Sugar 896 160 200 3,316 780 420 1,600 280 800 159 163 367 430 170 339 244 245 159 1032 Butter 1 102 66 147 18 33 60 162 121 6 23 1 3 12 10 1057 Whole milk . . . . . 144 358 25 1056 B read 6 1054 Meat 9 1088 Bananas 320 208 173 11 897 Breakfast food . 1 1055 Baked beans 19 Total diet. 7,555 92 2,117 68 427 34 328 6 1,362 28 81 1090 Feces 14 Amount digested. .- . 2,049 97 393 92 322 98 1,334 98 67 Per cent digested 82 The results of these 6 experiments are summarized in Table 8. Table 8. — Summary of results (f digestion experiments Nos. 284-289. Ex- Kind of experiment. Coefficients of digestibility. peri- ment No. Total organic matter. t Protein. Fat. Carbohy- drates. Ash. 284 286 288 Rest experiments do do Average Work experiments do do Average Per cent. 95 96 96 Per cent. 90 92 91 Per cent. 95 95 95 Per cent. 97 98 98 Per cent. 73 79 79 96 j 91 95 98 77 285 287 289 97 96 97 93 90 92 98 97 98 98 97 98 82 78 82 97 92 98 98 81 24 As regards protein and carbohydrates, the average digestibility was practically the same (hiring the period when work was performed as when it was not. In the case of the fat, the average coefficient was slightly larger duritig the work period in each experiment. On the whole, the results indicate that meat, or a diet including a generous proportion of meat, was cpiite thoroughly assimilated by a subject per- forming a considerable amount of muscular work each day as well as when not working, and that the digestibility of the diet was not appre- ciably affected by the amount of muscular work performed. The latter deduction is in accord with those drawn by Wait °- and b}^ At- water and Sherman,'' from investigations on the effect of muscular work upon digestibilit3^ DETAILS OF EXPERIMENTS WITH SIMPLE DIET, INCLUDING MEAT. Experiments such as those considered above show the digestibility of the total diet including meat, but thev afford no indication of the digestibility of the meat itself. This may or may not be the same as that of the diet as a whole. It is very desirable, however, to know what proportion of the nutrients of meat will be digested when the meat is eaten in combination with other food materials. Particular attention was devoted to a study of this subject in connection with these investigations, and in all 44 experiments were made in which the digestibility of the meat was determined. In 21 of these experiments the same kinil and cut of meat — beef round — was cooked by different methods, namely, in water at 80° to 85° C. for one, two, and three hours, and by pan broiling, frpng, and roasting; in 3 experiments beef shoulder was cooked in water for two hours; in 7 experiments beef ribs roasted were used; and in 13 experi- ments other kinds of meat, namely, veal, mutton, and pork, were cooked by roasting. The subjects in these experiments were eight young men, designated as A, B, D, E, F, H, I, and J. Subjects A and B were chemists, who had served in the experiments reported in preceding pages. Subjects D, E, F, and H were university students, aged 20, 22, 24, and 21 years, respectively, who were employed more or less in the laboratory. Sub- ject I was a high school pupil, 15 years old, who worked in the labora- tory during spare hours. Subject J was a janitor, 25 years old. All of the subjects were in good health, and none of them found the exac- tions of the experiments in any way disagreeable. Subject B served in 18 experiments; he was in nearly every one of the different series, which were continued at intervals through four years. The experi- oU. S. Dept. Agr., Office of Experiment Stations Bui. 89, p. 73. 6U. S. Dept. Agr., Office of Experiment Stations Bui. 98, p. 56. 25 ments with the other subjects were practically duplicates or triplicates of those with liim. During this time liis weight varied from 135 to 153 pounds, but in most of the experiments it was somewhere near 145 pounds. The weight of subject E varied from 118 to 125 pounds, and that of I from 132 to 142 pounds, in the experiments in which they served. Subject A weighed about 170 pounds, D about 152 pounds, F about 137 pounds, H about 140 pounds, and J about 130 pounds in each experiment in which they served. Seven of the experiments continued two days, and all the others three days, as indicated later in the data of the experiments. In each case a very simple diet including the meat was eaten, as explained below, in order that the digestibility of the meat might be calculated. Experimental method. — The digestibility of single food materials is sometimes studied by experiments in which the diet consists only of the material under consideration. There are several objections to such a method, however. In the first place, it is generally difiicult to continue the experiment long enough to obtain satisfactory itsults, because no matter how palatable the single food may be at first, to the ordinarv individual accustomed to a mixed diet it commonlv becomes distasteful, and sometimes the digestive functions are disturbed to such an extent that the results of the experiment are impaired. In the second place, even if the diet could be endured for a sufficient length of time, the digestibility as thus determined might differ from that, of the same material when eaten in connection with other foods. As Prausnitz ** has pointed out, there are three possibilities: (1) Each food may be digested as it would be if used alone; or (2) the digesti- bility of one may be increased, or (3) it may be diminished by the addition of the others. In digestion experiments made in this country it has been observed that the digestion of foods in a mixed diet is commonly more complete than that of any of the foods when eaten alone. The question to be studied in these experiments mth meat was, as suggested above. What proportion of each of the nutrients of meats of different kinds and cooked in different ways would be digested when the meat forms part of a diet of ordinary food materials? It was believed that a tolerably accurate answer to this question could be obtained from experiments with a very simple diet in which meat formed a considerable proportion of the total food eaten. Such a diet may be consumed with comfort for a sufficient length of time, even when the number of foods is small, and it has been, found that in a diet of this character the nutrients are generally as thoroughly •digested as in one composed of a larger number of food materials. Furthermore, the digestibility of the nutrients of a given material in the simple diet may be calculated when that of the foods with which a Arch. Hyg., 17 (1893), p. 626. 26 it is eaten is known or may bo assumed. Woods " and Snyder'' liave in this way studied the digestibihty of bread from the results of experi- ments with bread and milk. The ingredients of the feces that would be derived from the milk they calculated by use of previously deter- mined factors for the digestibility of the milk, and assumed that the difference between these and the total ingredients of the feces would represent the ingredients due to the bread. A similar method was followed by the authors of this report in the series of experiments, with meat here considered. The diet consisted mainly of bread and meat, with milk or butter, or in some cases both, in addition. The subjects ate such quantities of any of these mate- rials as they desired at each meal, though it was- understood l)y all that the foods other than meat were eaten simply to keep the diet palatable and agreeable, and that the purpose was to have the meat form as large a proportion of the whole ration as was consistent with their comfort. The amounts of meat consumed by the same subject varied considerably in different experiments, principally because of differences in palatability due to different methods of preparation; but in all cases the quantity of meat eaten^formed a relatively large pro]5ortion of the total diet. Since the materials other than meat were few in number, and were those the digestibility of which may be assumed ^vith reasonable accuracy for the conditions of these experi- ments, it is possible to calculate quite satisfactorily the digestibility of the meat from the data obtained in the experiments. The digestibility of the diet as a whole was found in the usual manner by subtracting from the amount of each nutrient of the total diet the amount of the corresponding ingredient in the total feces. In order to compute the digestibility of the protein and fat of the meat alone it was necessary to assume certain more or less arbitrary factors for the digestibility of the other foods eaten with the meat. For the purpose of these investigations it was assumed that 89 per cent of the protein and 90 per cent of the fat of the bread would be digested, these factors being based upon the results of digestion experiments with bread carried on by Woods and Snyder (above referred to) in connection with the nutrition investigations of the Department of Agriculture. In studying the digestibility of bread it was assumed that 98 per cent of the protein and 99 per cent of the fat of the milk and butter eaten with the bread would be digested, and these factors have also been applied to the same materials in the present experiments. The method of estimating the digestibility of meat b)^ the applicati(m of the above factors to the foods other than meat may be illustrated by data from experiment No. 293. In this case 0.8 gram of the total aU. S. Dept. Agr., Office of Experiment Stations Bills. 85, 143. b\J. S. Dept. Agr., Office of Experiment Stations Buls. 101, 126, 156. 27 protein of the diet was derived from butter, of which 99 per cent was assumed to be digested, thus leaving a neghgible quantity in the feces; and 46.6 grams of protein were derived from bread, of which 89 per cent was assumed to be digested, leaving 5.1 grams in the feces. The total protein of the feces was 15 grams. . Subtracting from this the sum of the amounts calculated as due to bread and milk, 5.1 grams, would leave 9.9 grams of the protein of the feces as due to meat. The total quantity of protein digested from the meat would then be 168.3 — 9.9=158.4 grams. Dividing this by the total in the meat consumed, 168.3 grams, and multiplying by 100, gives 94.1 per cent as the coefficient of digestibility of the meat protein. In like manner the digestibility of the fat of the meat was calculated. EXPERIMENTS WITH LEAN BEEF COOKED IN WATER FOR ONE HOUR. In the following 5 experiments the meat used consisted of lean beef round, which in each case was cooked in water at 80° to 85° C. for one hour. Experiment No. 293 with subject A and No. 294 with subject B began with breakfast December 8, 1900, and continued two days (6 meals). The diet consisted of meat, bread, and butter. The cut of meat used in these experiments was from an animal about 4 years old. Experiments Nos. 297, 300, and 301 with subjects D, E, and B, respectively, began with breakfast August 21, 1901, and continued three days (9 meals). The diet consisted of meat, bread, butter, and milk. The meat was from an animal about 3 years old. The data of these experiments are given in Table 9. Table 9. — Results of digestion experiments with beef round cooked one hour in water at 80 to 85° C. Lab- ora- tory No. Weight of mate- rial. Total organic matter. Protein (NX6.25). Fat. Carbohy- drates. Ash. 1131 Experiment No. 29S, subject A . Meat Orams. 640.0 tiOO.O 135.0 Grams. 193.3 .327. 9 125.9 Grams. 168.3 46.6 ' .8 Grams. 25.0 2.3 125. 1 Grams. Grams. 11.3 1132 Bread 279. 1 4.1 1133 Butter .5 Total diet 1,375.0 38.8 647.1 30.9 215.7 15.0 9.9 200.7 158.4 93.0 94.1 152.4 3.4 1.9 149.0 23.1 97.8 92.5 279.1 12.5 15.9 1138 Total feces 4.1 Estimated feces from meat Amomit digested: From total diet. 616. 2 266. 6 11.8 From meat alone Per cent digested : From total diet 95.2 95.5 74.2 From meat alone Experiment No. 29^, subject B. Meat 1131 7(i(). 5 .500.0 95.0 231.5 273.3 88.6 201.5 38.8 .6 ;?o.o 1.9 88.0 13.5 1132 B read 232. 5 3.5 1133 Butter .3 Total diet 1,36L5 593.4 240.9 119.9 232.5 17.3 28 Table 9. — Resitllx of digestion ex perlments with heef round cooked one hour in water at j; 80 to 85° C— Continued. ' Lab- ora- tory No. Weight of mate- rial. Total organic matter. Protein (NX6.25). Fat. Carbohy- drates. .\sh. 1139 Experiment No. 294, subject B —Con. Total feces Orams. 27.1 Orams. 20.7 Grams. 7.1 3.8 233.8 198.7 97.1- 98.6 Grams. 3.2 2.1 116.7 27.9 97.3 93.1 Grams. 10.5 Gra ins. 4 6 Estimated feces from meat Amomit digested: From total diet 5"72.6 222.1 12.7 From meat alone Per cent digested: From total diet 96.5 95. 5 73 6 From meat alone Experiment No. 397, subject D. Meat 1244 1,000.0 100.0 1.8 3, 073. 2 297. 6 .53.7 1.6 358. 6 274.2 7.2 97." i" 23.4 .7 1.6 120.8 16.2 1233 Bread 45.8 .7 1208 Butter 1234 Milk 140.7 21 2 Total diet 4,175.0 21.5 711.5 14.7 378.5 .5.9 3.2 372.6 271.0 98.4 98.9 146.5 2.6 1.3 143.9 22.1 98.2 94.3 186.5 6.1 38.1 1223 Total feces 5.0 Estimated feces from meat Amount digested: From total diet 696.8 180.4 33.1 From meat alone Percent digested: From total diet 97.9 96.7 86.8 From meat alone Experiment No. 300, subject E. Meat 1244 1,150.0 500.0 4,021.5 342.2 268. 6 469.3 315.3 36.0 127.1 26.9 3.7 158.0 18.6 1233 Bread 228.9 184.2 3.4 1234 Milk Total diet 27.7 5,071.5 55.6 1,080.1 28.9 478.4 15.7 9.2 462. 7 306.2 96.7 97.1 188.6 9.5 7.5 179.1 19.4 94.5 72.0 413.1 3.7 49.7 1248 Total feces 17.7 Estimated feces from meat Amount digested: From total diet 1,051.2 409.4 32.0 From meat alone Per cent digested: From total diet 96.5 99.1 64.3 From meat alone Experiment No. 301, subject B. Meat B read 1244 1,050.0 COO. 50.0 2, 353. 2 312.5 322.3 44.2 274. 6 287.9 4,3.2 .3 74.4 24.6 4.4 43.8 92.5 17.0 1233 274.6 4.0 1208 Butter .1 1234 Milk 107.8 16.2 Total diet 4,054.2 37.6 953.6 24.2 405.8 11.2 5.0 394. 6 283.0 97.2 98.3 165.3 4.0 2.2 161.3 22.4 97.6 91.0 382.4 8.9 37.3 1252 Total feces 8.1 Estimated feces from meat Amount digested: From total diet 4,015.6 929.3 373.5 29.2 From meat alone Per cent digested: From total diet 97.5 97.7 78.4 From meat alone EXPERIMENTS WITH LEAN BEEF COOKED IN WATER FOR TWO HOURS. In the five experiments followino; lean beef round cooked in water at 80 to 85° C, for two hours was used. Experiment No. 290, with subject A, and No. 292, with subject B, bejjan with breakfast November 21, 1900, and continued two days. Th(> diet consisted of meat, bread, and butter. Tlie cut of meat was from an animal about 6 years old. Experiment No. 291, with subject B, beit nlono. 31 EXPERIMENTS WITH LEAN BEEF PAN BROILED. The three following experiments were made \{^ith lean beef from an animal -about 3 years old. The meat was cut into steaks about an inch tliick, and pan broiled (fried without added fat) until well done. The cooked meat was then cut into strips, mixed with gravy obtained in cooking, seasoned to taste with salt and pepper, and then passed twice through a. sausage mill. As thus prepared it was fairly well relished by each subject. All the subjects ate bread and milk in addition to the meat, and subject F used a little butter also. Experiment No. 371, ^\dth subject F, and No. 372, with subject E, began with dinner March 18, 1901 ; and No. 373, with subject B, began with supper March 17. Each experiment continued three days (9 meals). The data of the experiments are given in Table 12. Table 12. — Results of digestion experiments with beef round pan oroiled. Lab- ora- tory No. Weight of mate- rial. Total organic matter. Protein (NX 6.25). Fat. Carbohy- drates. Ash. 1311 Experiment JVb. 371, subject F. Milk Orams. 3, 427. 04 50.00 600.00 1, 100. 00 Grams. 394. 45 44.45 341. 58 447. 70 Grams. 92.53 .40 56.04 313. 06 Grams. 147. 70 44.05 3.24 134. 64 Grains. 154. 22 Grams. 22.62 1312 Butter 1.18 1327 Bread 282. 30 5.04 1313 Meat.. . 28.28 Total diet 1,228.18 40.32 462. 03 17.95 9.93 444. 08 303. 13 96.12 96.83 329. 63 5.07 2.83 324. 56 131. 81 98.46 97.90 436. 52 17.30 57.22 1318 Total feces 59.83 14.45 Estimated feces from meat Amount digested: From total diet 1, 187. 86 419. 22 42.77 From meat alone Percent digested: From total diet 96.70 96.03 74.75 From meat alone Experiment No. il2, subject E. Milk 1311 3,934.30 700. 00 1,200.00 4.52. 84 398. 51 488. 40 106. 23 65.38 341. 52 169. 57 3.78 146. 88 177. 04 329. 35 25.96 1327 Bread 5.88 1313 Meat 30.96 Total diet 1,339.75 23.51 513. 13 14.16 4.84 498. 97 330. 68 97.24 98.58 320. 23 3.59 1.52 316. 64 14a 36 98.88 98.97 506. 39 5.76 62. 80 1322 Total feces 40.52 11. 86 Estimated feces from meat Amount digested: From total diet 1,316.24 500.63 50.94 From meat alone Percent digested: From tota 1 diet 98.24 98.86 81.11 From meat alone Experiment No. 373, subject B. Milk.. 1311 2, 64b. 58 300.00 1,200.00 304. 63 170. 79 488.40 71.46 28. 02 341. 52 114. 07 1.62 146. 88 119. 10 141. 15 17.46 1327 Bread 2.52 1313 Meat 30.96 Total diet 963. 82 28.90 441.00 11.57 7.06 429. 43 334. 46 97.38 97.93 262. 57 4.58 3.28 257. 99 143. 60 98.26 97.77 260. 25 . 12.75 50.94 1326 Total feces. . 42.18 9.95 Estimated feces from meat Amount digested: From total diet. . 934. 92 247.50 40.99 From meat alone. . . . Percent digested: From total diet 97.00 95.10 80.48 From meat alone . 4663— Bull. 193—07- 32 EXPERIMENTS WITH LEAN BEEF FRIED. The 3 following experiments, Nos. 374 to 376, with subjects F, E, and B, respectively, began with breakfast April 2, 1902,^ and con- tinued three days (9 meals). The meat used was lean beef round from an animal about 3 j'ears old. It was cut into steaks about half an inch thick, then fried in hot lard until well done. The cooked steaks were cut into strips, seasoned to taste with salt and pepper, and passed twice through a sausage mill. The meat was rather dry and not very well relished by the subjects. All the subjects ate bread and milk in addition to the meat, and subject F used some butter also. Table 13 contains the data of the experiments. Table 13. — Results of digestion experiments with beef round fried in hot lard. Lab- ora- tory No. Weight of mate- rial. Total organic matter. Protein (NX 6.25) . Fat. Carbohy- drates. Ash. 1329 Experiment No. 374, subject F. Milk Grams. 3,805.00 50.00 557. 20 800. 00 Grams. 445. 66 44.45 302. 11 361. 52 Grams. 108. 82 .40 ,51. 88 271. 76 Grams. 161. 71 44.05 1.50 89.76 Grams. 175. 03 Grams. 31.58 1312 Butter 1. 18 1328 Bread 248. 73 4.63 1330 Meat 20.64 Total diet 1, 153. 64 35.45 432. 86 15.46 7.58 417. 40 264. 18 96.43 97.21 297. 02 3.76 1.55 293. 26 88.21 98.73 98.27 423.76 16.23 58.03 1335 Total feces 54.20 14.06 Estimated feces from meat Amomit digested: From total diet 1, 118. 19 407. 53 43.97 From meat alone Per cent digested : From total diet 96.93 96.17 75. 77 From meat alone Experiment No. 375, subject E. Milk 1329 3,651.22 400. 00 900.00 427-56 216.88 406. 71 104.42 37.24 305. 73 155. 18 1.08 100. 98 167. 96 178. 56 30.30 1328 Bread 3.32 1330 Meat 23.22 Total diet 1,051.15 37.73 447. 39 19.95 13.77 427. 44 291. 96 95.54 95.50 257. 24 5.93 4.27 251.31 96.71 97.69 95.77 346. 52 11.85 56.84 1339 Total feces 65.03 20. 12 Estimated feces from meat Amomit digested: From total diet 1,013.42 334. 67 36.72 From meat alone Percent digested: From total diet 96.41 96.58 04. 60 From meat alone Experiment No. 376, subject B. Milk 1329 4,237.39 300. 00 700.00 496. 20 162. 66 316. 33 121. 19 27.93 237. 79 180.09 .81 78.54 194. 92 133. 92 35.17 1328 B read 2.49 1330 Meat 18.06 Total diet 975. 19 27.60 386. 91 8.87 3.37 378. 04 234.42 97.73 98.58 259. 44 2.77 .89 256. 67 77.65 98.93 98.87 328. 84 15. 96 55.72 1343 Total feces 42.21 11.12 Estimated feces from meat From total diet. . . 947. 59 312. 88 44.60 From meat alone Percent digested: From total diet. 97.17 95.15 80.04 From meat alone EXPERIMENTS WITH LEAN BEEF ROASTED. Experiments Nos. 377-379, with, subjects F, E, and B, respec- tively, began with breakfast April 16, 1903, and continued three days (9 meals). The meat used in these experiments was lean beef 33 round from an animal about 2 years old, roasted in an oven until well done. The cooked meat was cut into strips, mixed with gravy obtained in roasting, seasoned to taste with salt and pepper, and passed twice through a sausage mill. It had an excellent flavor and was relished by all the subjects. Table 14 gives the data of these experiments. Table 14. — Rvsults of digestion experivients with beef round roasted. Lab- ora- tory No. Weight of mate- rial. Total organic matter. Protein (N X 6.25). Fat. Carboyh- d rates. Ash. 1346 Experiment No. 377, subject F. Milk Grams. 3,950.19 50.00 400.00 1,200.00 Grams. 478. 36 43.96 223. 04 456. 84 Grams. 114. 15 .23 37.64 357.24 Grams. 164. 33 44.73 2.36 99.00 Grams. 199. 88 Grams. 29.03 1345 Butter 1.20 1344 Bread 183. 04 2.88 1347 Meat 38.40 Total diet 1,203.20 22.83 509. 26 9.97 3.55 499.29 353. 69 98.04 99.01 311.02 2.02 382.92 10.84 72.11 1352 Total feces 35.01 8.73 Estimated feces from meat . ... Amount digested: From total diet . . 1,180.37 309.00 99.60 99.33 100. 00 372.08 63.38 From meat alone Percent digested: From total diet 98. 10 97.17 87.89 From meat alone Experiment No. 378, subject E. Milk 1346 3,907.84 300. GO 1,000.00 473. 24 167. 28 380.70 112.94 28.23 297. 70 162. 57 1.77 83.00 197. 73 137.28 29.31 1344 B read 2.16 1347 Meat 32.00 Total diet 1,021.22 18.86 438. 87 10.81 5.45 428.06 292. 25 97.54 98.17 247. 34 2.66 .86 244. 08 82.14 98.92 98.96 335. 01 5.39 63.'47 1356 Total feces . . 35.04 11.40 Estimated feces from meat Amount digested: From total diet . . . 1,002.36 329. 62 52.07 From meat alone Percent digested: From total diet 98.15 98.39 82.04 From meat alone Experiment No. 379, subject B. Milk B read 134(i 1344 3, 407. 87 .300. 00 1,200.00 412. 69 167. 28 456. 84 98.49 28.23 357. 24 141.76 1.77 99.60 172. 44 137. 28 25.56 2. 16 1347 Meat 38 40 Total diet 1,036.81 18.05 483. 96 6.32 1.24 477. 64 356. 00 98.69 99.65 243. 13 1.74 .15 241. 39 99.45 99.28 99.85 309. 72 9.99 66. 12 1360 27.78 7 33 Estimated feces from meat Amount digested: From total diet 1,018.76 299. 73 58. 79 From meat alone Percent digested: From total diet 98.24 96.77 88.91 From meat alone 1 EXPERIMENTS WITH FAT BEEF COOKED IN WATER FOR TWO HOURS. Experiments Nos. 368-370, with, subjects F, E, and B, respectively, began \vith breakfast February 26, 1902, and continued three days (9 meals). The meat used in these experiments was fat beef shoulder, from an animal about 2% years old, cooked in distilled water at 80° to 85° C. for two hours. The cooked meat was relished by all the subjects throughout the experiments. The diet included bread and milk in addition to the meat, and subject F used some butter also. The data of the experiments are tabulated in Table 15. 34 Table 15. — Results of digestion experiments with fat beef shoulder cooked two hours in ■water at 80^ to 85° C. Lab- ora- tory No. Weight of mate- rial. Total organic matter. Protein (NX 6.2.5). Fat. Carbohy- drates. Ash. 1285 1286 Experiment No. 368, subject F. Milk lUitter Grams. 2,627.47 50.00 600.00 1,400.00 Orams. 313.98 45.26 329.28 686.98 Grams. 71.99 .30 51.66 316.54 Grams. 109.57 44.96 5.28 370.44 Grams. 132.42 Grams. 17.87 1.33 1281 Bread. 272.34 5.28 1287 Meat •'2. 40 Total diet 1,375.50 54.18 440.49 18.67 11.55 421.82 304.99 95.76 96.35 533.25 10.01 7.94 520.24 362. 50 98.11 97.86 404. 76 25.50 46.88 1291 Total feces 75.76 14.70 Estimated feces from meat Amount digested: From total diet 1,321.32 379.26 32.18 From meat alone Per cent digested : From total diet 96.06 93.70 68.64 From meat alone Experiment No. S69, subject E. Milk » 1285 2,832.84 793.61 590.00 1,403.00 338.52 79.35 274.45 683.98 77.62 18.09 43.05 316.54 118.13 22.14 4.43 370.44 142.77 39.13 226.95 19.26 1301 do 5.32 1284 Bread 4.40 1287 Meat . . 22.40 Total diet 1,379.26 40.53 455.33 18.63 ^1.98 436.67 304.56 95.91 96.22 515.11 16.06 14.22 499.05 356.22 96.88 98.16 408.85 5.81 51.38 1295 Total feces 67.32 16.46 Amount digested: From total diet 1,338.76 403.04 34. 92 From meat alone Percent digested: From total diet 97.06 98.58 67.96 From meat alone Experiment No. 370, subject B. Milk 1285 1,035.10 400.00 1,503.00 123.69 219.52 736.05 28.36 34.44 339. 15 43.16 3.52 396.90 52.17 181.56 7.04 1284 1287 Bread Meat 3. 52 24.00 Total diet 1,079.26 29.98 401.95 12.29 7.93 389.66 331.22 96.94 97.67 443.58 9.04 8.26 434.54 388.64 97.97 97.92 233. 73 8.65 34.56 1299 Total feces . . . . 40.76 5.15 P-stimated feces from meat Amount digested: From total diet 1,049.28 225.08 29.41 From meat alone Percent digested: From total diet 97.22 96.30 85.10 From meat alone . . . EXPERIMENTS WITH BEEP RIBS ROASTED. In the following 7 experiments the cut of meat used w^as beef ribs, roasted in a gas oven until well done. The bones and surplus fat were removed from the roasted meat, and the remainder was used. The diet in each case included bread, butter, and milk in addition to the meat. Each experiment continued three days (9 meals). Experiments Nos. 422 and 423, \\nth subjects I and B, began with breakfast December 31, 1902. The meat used was from a 4-year-old Shorthorn cow in prime condition at the time of slaughter. Experi- ments Xos. 426 and 427, with subjects B and J, began wdth breakfast January 21, 1903. The meat used was from a 2-year-old Aberdeen- Angus cow, in rather thin condition at the time of slaughter. Experi- ment No. 428, with subject B, began mth breakfast January 28, 1903. 35 The meat used was from a yearling Aberdeen- Angus steer in prime condition at the time of slaughter. Experiments Xos. 429 and 430, with subjects B and J, began with breakfast February 4, 1903. The meat used was from a well-fattened animal. Table 16 contains the data of these experiments. Table 16. — Results of digestion experiments ivith bt ;e/ ribs roasted. Lab- ora- tory No. ': Weight of mate- rial. Total organic matter. Protein (N X 6.25) . Fat. Carbohy- drates. Ash. 1523 1524 1526 Experiment No. 4-1?, subject T. Milk Bread Butter Meat, Grams. 4,037.77 800. 00 100. 00 1,100.00 Grams. o3S. 24 444. 48 84.80 595. 43 Grams. 131. 23 09. 44 .55 220. 44 Grams. 220. 56 3.20 84.25 374. 99 Grams. 176. 45 371. 84 Grams. 26.25 6.96 9 37 1525 21.23 Total diet .' 1,66.3.05 44. .38 421.66 12.63 2. .37 409.03 218. 07 97.00 98.92 693. 10 7. 32 .3.85 685. 78 .371. 14 98.94 98.97 548. 29 24.43 56.81 1530 Total feces. . . . . 59.48 9.83 Estimated feces from meat Amount digested: From total diet 1,618 67 523. 86 46.98 From meat alone Percent diarested: From total diet 97.32 95.54 82.70 From meat alone Experiment No. 4.?3, subject B. Milk 1 1523 3, 658. 29 800 00 50.00 1, 100. 00 487. 65 444. 48 42.45 595. 43 118. 89 69.44 .28 220. 44 208.89 3.20 42.17 374.99 159.87 371. 84 23.78 1524 Bread 6.96 1526 Butter Meat Total diet Total feces 1.18 1525 21.23 1534 ""60.' 97" 1,570.01 45.39 409. 05 11.05 1.03 398.00 219. 41 97.30 99. 53 629. 25 6.51 3.68 623. 74 .371. 31 99.12 99.02 531. 71 27. 83 53.15 11. .34 Estimated feces from meat . ... Amount digested : From total diet 1,524.62 503.88 41.81 From meat alone Percent digested: From total diet 97.11 94.77 78.66 From meat alone Experiment No. 126, subject B. Milk 1562 3,858.48 700 00 100 00 1, 100. 00 463. 01 392. 07 86. CO 471. 35 115. 75 64.82 .70 271. 04 170. 54 2.52 85.60 200. 31 176. 72 324. 73 27.01 1563 Bread 5.04 1564 Butter 2.38 1561 Meat 28.05 Total diet 1, 413. 03 38.11 452 31 9.21 2.08 443. 10 268. 96 97.96 99. 23 459. 27 3.90 1.08 455. 37 199. 23 99.15 99.46 501. 45 25. 00 62.48 1568 Total feces 51.62 10.08 Estimated feces from meat Amount digested: From total diet 1,. 374. 92 476. 45 .52. 40 From meat alone Per cent digested: From total diet 97.30 95.02 83.87 From meat alone Experiment No. 437, subject J. Milk B read Butter Meat Total diet ! 1562 1563 1564 2,863.85 800.00 100.00 1,. 500. 00 343 66 448.08 86.60 642.75 85.92 74.08 .70 369.60 126.58 2.88 85.90 273. 15 131.16 371.12 20.05 5.76 2.38 1561 - ... - 38.25 1,. 521. 09 18.72 530. 30 6.38 488.51 2.54 .13 485.97 273.02 99.48 99.95 .502. 28 9.80 66.44 1572 Total feces 25.62 4.87 Estimated feces from meat Amount digested: From total diet 1,502.37 523.92 369.60 98.80 100.00 492.48 61.57 From meat alone Percent digested: From total diet 98.77 98.05 92.67 From meat alone 36 Takt;E 1(i. — Results of digestion experiments iidth beef ribs roasted — Coutimu'd. Lab- ora- tory No. Weight of mate- rial. Total org.inic matter. Protein (NX 6.25). Fat. Carbohy- drates. Ash. 1597 Experiment No. 4^8, subject B. Milk Grams. 2,426.80 500.00 100.00 1,100.00 Grams. 292.43 273.65 89.00 534.82 Grams. 73.29 41.95 .67 226. 16 Grams. 100.95 1.90 88.33 308.66 Grams. 118.19 229.80 Grams. 16.02 1596 B read 4.80 1598 Butter 2.38 1595 Meat Total diet 26. 06 1,189.90 29.03 342.07 10.05 3.97 332.02 222. 19 97.06 98.25 499.84 3.92 1.84 495.92 306.82 ,99.22 99.40 347.99 15.06 49.27 1602 Total feces 38.30 5. 77 Kstimated feces from nieat Amount digested : From total diet 1,160.87 332.93 43.50 From meat alone Per cent digested : From toliil diet • 97.55 95.67 88.29 From meat alone Erperiment No. 4^9, subject B. Millc 1 1619 3,488.72 700.00 50.00 1,100.00 414.46 400. 19 44.45 597.30 104.31 60. 20 .41 259. 93 146.53 5.53 44.04 337.37 163.62 334.46 23.72 1618 B read 5.88 1620 Butter... 1.01 1617 Meat 25.74 Total diet 1,456.40 17.81 424.85 6.91 .29 ■ft7.94 259.64 98.37 99.89 533.47 2.35 498.08 8.55 .56. 35 1624 Total feces 23.35 3.71 Estimated feces from meat Amount digested: From total diet 1,438.59 .531. 12 3.37.37 99.56 100.00 489.53 52.64 From meat alone Percent digested: From total diet 98.78 98.28 93.42 From meat alone Experiment No. 430, subject J. Milk 1619 2,827.99 800.00 100.00 1,600.00 335.97 457.36 86.91 868.80 84.56 68. 80 .82 378.08 118.78 6.32 86.09 490. 72 132.63 382.24 19.23 1618 B read . 6.72 1620 Butter 2.02 1617 Meat 37.44 Total diet • 1,749.04 41.28 532.26 19.81 10.47 512.45 367.61 96.28 97.23 701.91 5.91 3.23 696.00 487.49 99.16 99.34 514.87 15.56 65.41 1628 Total feces . . 56. 18 10.02 Estimated feces from meat Amount digested: From total diet 1,707.76 499.31 55.39 From meat alone Per cent digested : From total diet 97.64 96.98 84.68 From meat alone EXPERIMEIS^TS AVITII FAT VEAL LEG ROASTED. In these 6 experiments the meat used was very fat veal leg, roasted in a gas oven until well done, and seasoned to taste with salt and pepper. The cooked meat was relished by each subject throughout the experiments. Each experiment continued thi-ee days (9 meals). All the sub- jects ate bread and milk in addition to the meat, and subjects I and B used butter also. Experiments Nos. 380, 382, and 383, with subjects H, I, and B, respectively, began with breakfast September 24, 1902. The meat used was from a calf about 10 weeks old. Ex- periments Nos. 419-421, with subjects H, I, and B, began with breakfast December 10, 1902. The data of these experiments are given in Table 17. 37 Table 17. — Results of digestion experiments with veal roasted. Lab- ora- tory No. Weight of mate- rial. Total organic matter. Protein (NX 0.25). Fat. Carbohy- drates. Ash. 1405 Experiment No. S80, subject H. Milk Grams 1,361.95 1, SCO. 43 350.00 1,300.00 Grams. 180.86 216.55 192. 61 580. 84 Grams. 43. 17 56.56 31.68 365. 56 Grams. 72.86 71.81 1.36 21.5.28 Grams. 64.83 88.18 1.59.57 Grams. 9.81 1429 do . . 12. 47 1404 Bread . 3.01 1406 Afpnt 30.42 Total diet 1,170.86 32.36 496.97 18.41 12.93 478. 56 .3.52.63 96.30 96.46 361.31 4.01 2.43 357.30 212. 85 98.89 98.87 .31 2. .58 9.94 302. 64 96.83 .55. 71 1411 Total feces 45.56 7.91 Kstimnted fece.s from meat Amount digested: From total diet 1,138.50 47.80 Krom moi)t alone Percent digested: From total diet 97.24 85.80 1405 1429 1404 Experiment No. S82, subject I. Milk 1,3.52.67 1,870.76 900.00 150. 00 1,600.00 179. 64 217. 76 495. 27 125. 26 714.88 42.88 .56. 87 81.45 1.23 449. 92 72. 37 72.21 3.51 124.03 264. 96 64.39 88.68 410. 31 9.74 do 12. .53 7.74 1407 ■Rnttpr 4.32 1406 37.44 1,732.81 42. 34 632.35 21. 35 10.38 (ill. 00 439. 54 96.62 97.69 537. 08 5. 35 2.31 .531. 73 262. 65 99.00 99.13 563. 38 15.64 71.77 1419 Total feces . 56.00 7.88 Amount digested: From total diet 1,690.47 547.74 63.89 Per cent digested: From total diet 97. .55 97.22 89.02 FroTTi mpfit filonp. Ezperiwent No. 3,SS. subject B. MUk 1 1405 632.00 1,301.58 400. 00 .50. 00 1,200.00 S3. 93 151.. 50 220. 12 41.76 536. 16 20.04 39. 57 36. 20 .41 337. 44 .33.81 50. 24 1.56 41.35 198. 72 30.08 61.69 182. 36 4.55 1429 ....do 8.72 1404 B read 3.44 1407 Butter . . . . 1.44 1406 Meat 28.08 Total diet. 1,033.47 2.5.93 433. 66 9.92 4.74 423. 74 332. 70 97.71 98. 59 325. 68 3.34 1.93 322.34 196. 79 98.97 99.03 274. 13 12.67 46.23 1423 Total feces 34.42 6.09 Estimated feces from meat .... Amount digested: From total diet 1,007.54 261.46 95.38 40.14 From meat alone Percent digested: From total diet 97.49 86.83 From meat alone . 1466 1467 Experiment No. 419, subject H. Milk 3,808.22 600.00 1,000.00 462. 70 321.72 317.20 119.20 48.06 283. SO 167.94 2.40 33.40 175.56 271.26 27.42 Bread... . . . 4.92 1469 24.70 1,101.62 25.18 451.06 13.31 5.64 437. 75 278. 16 97.05 98.01 203. 74 4.70 2.78 199.04 30.62 97.69 91.67 446. 82 7.17 57.04 1473 Total feces 39.79 11.16 Amount digested: 1,076.44 439.65 45.88 From meat alone. Per cent digested : From total diet 97.71 98.40 80.43 From meat alone. . Experiment No. 420, subject I. Milk. . . . 1466 3,994.34 700.00 150.00 1.100.00 485.31 375.34 132. 83 348.92 125.02 56. 07 .83 312. 18 176. 15 2.80 1,32. 00 36.74 184. 14 316. 47 28.76 1467 Bread 5.74 1468 Butter 2.43 1469 Meat 27.17 Total diet... . 1,342.40 19.29 494. 10 6.41 .24 487. 69 311.94 98.70 99.92 347.69 2.99 500.61 9.89 64.10 1477 To*^al feces 25.73 4.55 Estimated feces from meat Amount digested : From total diet 1,323.11 344. 70 36.74 99.14 100.00 490. 72 59.55 From meat alone. . . . ' Per cent digested : From total diet 98.57 98.02 92.90 From meat alone 38 Table 17. — Results of digestion expenments with veal roasted — Continued. Lab- ora- tory No. Weight of mate- rial. Grams. 2,574.66 700.00 100.00 1,000.00 Total organic matter. Protein (Nx 6.25). Fat. Caibohy- drates. Ash. 1466 1467 Experiment ^o. 4?1, gtibjeci B. Milk Bread Grams. 312.82 375. 34 88.55 317.20 Grams. 80.59 .56.07 .55 283.80 Grams. 113.54 2.80 88.00 33.40 Grams. 118.69 316. 47 Grams. 18.54 5.74 1468 Butter 1.62 1469 Meat 24.70 Total diet 1,093.91 19.69 421.01 5.90 237. 74 2.78 .48 234.96 32.92 '98.83 98.56 435. 16 11.01 50.60 1481 Total feces 26.87 5. 43 Estimated feces from meat Amount digested: From total diet 1,074.22 415. 11 283.80 98.60 100.00 424. 15 45.17 From meat alone Per cent digested : From total diet 98.20 97.47 89.27 From meat alone . . .- EXPERIMENTS WITH MUTTON LEG ROASTED. Experiments Nos. 381, 384, and 385, with subjects H, I, and B, respectively, began with breakfast October 8, 1902, and continued three days. All the subjects ate bread, milk, and meat, and subjects I and B added butter. The meat was very fkt leg of mutton, from an animal about 1 year old, roasted in a gas oven until well done, and was well relished by each subject. Subject H felt somewhat indis- posed toward the close of the experiment. The data of the experi- ments are given in Table 18. Table 18. — Results of digestion experiments with mutton roasted. Lab- ora- tory No. Weight of mate- rial. Total organic matter. Protein (NX 6.25). Fat. Carbohy- drates. Ash. 1435 Experiment No. S8t, subject H. Milk Grams. 3,166.11 500.00 1,000.00 200.00 Grams. 362.84 275.80 469.20 93.24 Grams. 103.22 45.40 251.00 59.14 Grams. 116.83 2.05 218 20 34.10 Grams. 142.79 228.35 Grams. 23.11 1437 Bread , 3.85 1438 Meat 28.90 1447 -do] 4.90 Total diet 1,201.08 53.02 458.76 23.65 16.59 435.11 293.55 94.85 94.65 371.18 6.45 5.80 364.73 247.22 98.26 97.09 371.14 22.92 60.76 1415 Total feces 73.85 11.30 Estimated feces from meat . Amount digested: From total diet. 1,148.06 348.22 49. 46 From meat alone Per cent digested : From total diet 95.59 93.82 81.40 From meat alone Experiment No. 384, subject I. Milk 1 1435 3,382.21 850.00 150.00 1,200.00 300.00 387.60 468.86 126.02 563.04 139.86 110.26 77.18 1.19 .301.20 88.71 124.80 3.49 124.83 261.84 51.15 152.54 388.19 62.69 1437 Bread 4.55 1436 Butter 4.77 1438 Meat 34.68 1447 .. -do 7.35 Total diet 1,685.38 52.27 578.54 22.05 11.34 556.49 378.57 96.19 97.09 566.11 6.84 3.99 559.27 309.00 98.79 98.73 .540.73 23.38 78.04 1442 Total feces 72.12 10.26 Estimated feci^s from meat Amount digested: From total diet 1,633.11 517.35 67.78 From meat alone Percent digested: From total diet 96.90 95.68 86.87 g ■ : "= ■■=■ 39 Table 18. — Results of digestion experiments with mutton roasted — Continued. Lab- ora- tory No. Weight of mate- rial. Total organic matter. Protein (NX 6.25). Fat. Carbohy- drates. Ash. 1435 Experivtent No. 385, subject 6. Milk Grams. 3,475.27 7.50.00 100.00 800.00 400.00 Grams. 398.26 413.71 84.01 375.36 186.48 Grams. 113.29 68.10 .79 200.80 118.28' Grams. 128.24 3.08 83.22 174.56 68.20 Grams. 156.73 342.53 Grams. 25.37 1437 Bread 5.77 1436 Butter 3.18 14.38 Meat . . . 23.12 1447 .do 9.80 Total diet 1,457.82 41.04 501.26 11.36 1.60 489.90 317.48 97.73 99.50 457.30 5.29 2.87 452.01 239.89 98.84 98.82 499.26 24.39 67.24 1446 Total feces . 53.29 9.78 Estimated feces from meat Amount digested: From total diet 1,416.78 474.87 57.46 From meat alone Per cent digested : From total diet 97.17 95.11 85.45 From meat alone. EXPERIMENTS WITH PORK ROASTED. Four experiments, each of three clays' (9 meals) duration, were made Avith very fat fresh pork (hani), roasted in a gas oven until well done, and seasoned to taste with salt and pepper. The meat was relished in all the experiments. In each case bread, butter, and milk were eaten in addition to the meat. Experiment No. 386 with subject I, and No. 387 with subject B, began with breakfast October 22, 1902. In these experiments most of the visible fat was removed from the meat before it was cooked. Experiments Nos. 424 and 425, with subjects I and J, began with breakfast January 13, 1903. The ham used in these experiments was from a Duroc-Jersey hog about 8 months old, fattened for market on a ration consisting of peas, oats, and barley. The entire ham with the bone, but with only a part of the skin, was roasted in a gas oven until well done. The bone and skin were then removed. Table 19 gives the data of these experiments. Table 19. — Results of digestion experiments with pork roasted. Lab- ora- tory No". Weight of mate- Tial. Total organic matter. Protein (NX 6.25^ Fat. Carbohy- drates. Ash. 1449 Experiment No. 386, subject I. Milk Grams. 4, 725. 38 700.00 150. 00 1,100.00 Grams. 543. 42 393. 47 129. 26 570. 46 Grams. 150. 27 64. 05 .83 350.02 Grams. 180. 98 2.17 128. 43 220. 44 Grams. 212. 17 327. 25 Grams. 39.22 1450 Bread. 4.97 1451 Butter 3.16 1452 Meat . 24.86 Total diet 1,636.61 28.47 56.5. 17 12. 79 2.73 552,38 347. 29 97.74 99.22 532. 02 4.39 1.08 527. 63 219. 36 99.17 99.51 539. 42 11.29 72.21 1456 Total feces 39.69 8.06 Estunated feces from meat Amount digested: From total diet 1,608.14 528. 13 64. 15 From meat alone Percent digested: From total diet 98.25 97.91 88.84 From meat alone 40 Table 19. — BenHltK of digestion experwients-with pork roasted — Continued. Lab- ora- tory No. Weight of mate- rial. Total organic matter. Protein (NX 6.2.5). Fat. Carbohy- dr.ates. Ash. 1449 Experiment Xo. 387, subject B. Milk Grams. 3,786.51 600. 00 100. 00 1,000.00 Grams. 435. 44 337. 26 86.17 518.60 Grams. 120. 41 .54. 90 .55 318. 20 Grams. 145.02 1.86 85.62 200. 40 Grams. 170, 01 280, 50 Grams. 31 43 1450 Bread 4,26 1451 Butter 2,11 1452 Meat 22,60 Total diet 1,377.47 32.91 494. 06 10.65 2.20 483. 41 316. 00 97.84 99.31 432.90 3.74 1.25 429.16 199. 15 99.11 ' 99. 38 4.50. 51 18.52 60, 40 1460 Total feces 44.73 11 Estimated feees from meat Amount digested: From total diet 1,344,56 431. 99 51.29 From meat alone Per cent digested: From total diet 97. 01 95.89 84.92 From meat alone _• . . . Experiment No. 424, subject I. Milk 1547 3,006.87 .500. 00 100. 00 1,000.00 343. 99 276. 15 88.80 453. 70 97.12 41.95 1.00 251. 30 116, 37 1.15 87.80 202. 40 130. 50 233. 05 21. 65 1548 1549 Bread Butter 4.00 1.09 1546 Meat . . 23.70 1,162.64 20.91 391. 37 8.60 2.04 •682.77 249. 26 97.80 99.19 407. 72 3.09 ,98 404.63 201.42 99.24 99.52 363. 55 9.22 50.44 1553 Total feces 28.70 5.31 Estimated feces from meat Amount digested: From total diet 1,141.73 354. 33 4.5. 13 From meat alone. Per cent digested: From total diet 98,20 97.46 89.47 From meat alone Experiment No. 425, subject J. Milk 1547 3, 166. 11 800. 00 150.00 1,000.00 362. 20 441. 84 133. 20 423.70 102. 26 67. 12 1.50 261. 00 122. 53 1.84 1.31. 70 162. 70 137. 41 372. 88 22.80 1548 B read 6.40 1.549 Butter 1.64 1560 Meat 32.30 Total diet 1,360.94 30.52 431.88 13.40 3.97 418. 48 257. 03 96.90 98,49 418. 77 4.05 1.32 414. 72 161. 38 99.03 99,19 510. 29 13 07 63.14 1557 Total feces 43.25 9.37 Estimated feces from meat- Amount digested: From total diet 1,330.42 497, 22 53.77 From meat alone Per cent digested: From total diet 97.76 97,44 85,16 From meat alone SUMMARY AND DISCUSSION OF RESULTS. In Table 20 are summarized the results of the 44 digestion experi- ments with a simple diet in which the amount of meat formed a large proportion of the total food eaten. The figures here given are the proportions of the different nutrients that were digested, that is, the coefficients of digestibility. 41 Table 20. — Coefficients of digestibility of nutrients of dijferent meats in experiments Nos. 290-301, 368-387, 419-430. Ex- Sub- ject. Kind of meat and method of cooking. Total diet. Meat alone. peri- ment No. Pro- tein. Fats. Car- bohy- drates. Per ct. 95.5 95.5 96.7 99.1 97.7 Ash. Pro- tein. Fat. 293 A. B D E B A B B E B A B F E B F E B F E B F E B I B B J B B J II I B H I B H I B I. B I J Lean beef round, cooked in water at 80-85° C. fori liour » Per ct. 93.0 97.1 98.4 96.7 97.2 Per ct. 97.8 97.3 98.2 94.5 97.6 Per ct. 74.2 73.6 86.8 64.3 78.4 Per ct. 94.1 98.6 98.9 97.1 98.3 Per ct. 92. 5 294 ... .do 9.3.1 297 do 94.3 300 do O72.0 301 do.. 91.0 Average 96.5 97.1 96.9 76.5 97.3 92.6 Lean Iseef round, cooked in water at 80-85° C. for 2 hours 290 91.4 96.3 97.2 96.6 97.0 97.1 92.5 97.7 97.7 97.9 94.6 94.4 97.1 98.3 94.6 67.5 79.7 80.6 65.5 67.1 91.9 97.3 98.4 97.4 98.0 89.7 291 do 88.7 292 do 95.5 298 do 88.7 299 do 89.3 Average .... . 95.7 96.6 95.8 72.0 96.6 90.4 Lean beef round, cooked in water at 80-85° C. for 3 hours 295 96.9 97.5 99.1 97.9 97.6 97.9 83.8 79.9 99.7 99.6 99.5 296 do 93.6 Average 97.2 98.5 97.7 81.8 99.7 96.6 I^ean beef round, pan broiled 371 96.1 97.2 97.4 98.5 98.9 98.3 96.0 98.9 95.1 74.8 81.1 80.5 96.8 98.6 97.9 97.9 372 373 do do 99.0 97.8 Average 96.9 98.5 96.7 78.8 97.8 98.2 Lean beef round, fried in hot lard do . . 374 375 96.4 95.5 97.7 98.7 97.7 98.9 96.2 96.6 95.2 75.8 64.6 80.0 97.2 95.5 98.6 98.3 95.8 376 do 98.9 Average 96.6 98.5 96.0 73.5 97.1 97.7 Lean beef round, roasted 377 98.0 97.5 98.7 99.3 98.9 99.3 97.2 98.4 96.8 87.9 82.0 88.9 99.0 98.2 99.7 100.0 378- do . . 99.0 379 do 99 9 Average ... 98.1 99.2 97.4 86.3 98.9 99.7 Fat beef shoulder, cooked in water at 80- 85° C. for 2 hours 368 95.8 95.9 96.9 98.1 96.9 98.0 93.7 98.6 96.3 68.6 68.0 85.1 96.4 96.2 97.7 97.9 3"9 do 96 2 370 do 97.9 96.2 97.7 96.2 73.9 96.8 97 3 Beef ribs, roasted 422 97.0 97.3 98.0 98.8 97.1 98.4 96.3 98.9 99.1 99.2 99.5 99.2 99.6 99.2 95.5 94.8 95.0 98.1 95.7 98.3 97.0 82.7 78.7 83.9 92.7 88.3 93.4 84.7 98.9 99.5 99.2 100.0 98.3 99.9 97.2 99 423 do 99 426 do 99 5 427 do 99 9 428 da 99 4 429 do 100 430 do 99 3 Average 97.5 £9.2 96.2 86.3 99.0 99 4 \ eal leg, roasted 380 96.3 96.6 97.7 97.1 98.7 98.6 98.9 99.9 99. Q 97.7 99.1 98.8 9d. 8 97.2 95.4 98.4 98.0 97.5 85.8 89.0 86.8 80.4 92.9 89.3 96.5 97.7 98.6 98.0 99.8 100.0 98 9 3S2 dj 99 1 383 dD 99 419 do 91 7 420 421 do do 98 6 Average 97.5 98.8 97.2 87.4 98.4 97 9 Mutton leg, roasted 381 94.9 96.2 97.7 98.3 98.8 98.8 93.8 95.7 95.1 81.4 86.9 85.5 94.7 97.1 99.5 98.0 384 385 do ' '". 98.7 98 8 Average 96.3 98.6 94.9 84.6 97.1 98 5 Pork (fresh ham), roasted 386 97-7 97.8 97.8 96.9 99.2 99.1 99.2 99.0 97.9 95.9 97.5 97.4 88.8 84.9 89.5 85.2 99.2 99.3 9a. 2 98. 5 99 5 387 d5 99 4 424 do 99 5 425 do 99 2 Average .... 97.6 99.1 97.2 87.1 99.1 99 4 .\verage for all experiments 96.9 98.3 96.6 80.7 98.0 97.1 o Not included in the average. 42 Digestibility of total diet. — One part of Table 20 shows the coeffi- cients of. digestibility of the nutrients of the total diet. In the average of the 44 experiments 97 per cent of the total ciuantity of protein eaten, 98 per cent of the total fat, and 97 per cent of the total carbohydrates were digested. If the 23 experiments with more varied diet, including meat, given on pages 13 to 23, are averaged, the coefficients for fat and car})ohydrates are identical with these just given, but that for protein is 93 per cent. The reason for this lower figure for protein in the more varied diets is that the latter contains relatively large proportions of vegetable foods, in which the protein is not so thoroughly digested as in meat, which formed so much larger proportion of the total food in the more simple diets. In the average of upward of 400 experiments ^\^th various kinds of mixed diets made in connection with the nutrition investigations of this Department the coefficients of digestibility of the nutrients were found to be protein 92, fat 95, and carbohydrates 97 per cent. It is apparent, therefore, that the nutrients in the simple diet used in the experiments here summarized were thoroughly digested. The minor averages in Table 20, i. e., the averages of the results of similar experiments, agree favorably with the general average. Thus the coefficients for protein range in the various averages from 96 to 98 per cent, those for fat from 97 to 99 per cent, and those for carbohydrates from 95 to 98 per cent. It is also noticeable that the results for different subjects in similar experiments agree, in almost every case, about as closely as can be expected in investigations of this nature. There are, in fact, only three noteworthy exceptions. In the experiments with lean beef cooked in water one hour, one subject digested 93 per cent of the protein, whereas the other four subjects digested 97 to 98 per cent. In the experiments with lean beef cooked in water two hours, one subject digested 91 per cent of the protein as compared with 96 to 97 for the other four subjects, and one subject digested 93 per cent of the fat, whereas each of the other four subjects digested 97 per cent. In all of the other experi- ments the agreement in results for all the different subjects on the same diet was satisfactorily close. It would appear from these data that differences in the method of cooking the meat had little influence upon the digestibility of the nutrients of the total diet. For example, lean beef round was cooked in six different ways, and in these experiments the coefficients for protein in the total diet range, in the averages, from 96 to 98 per cent, those for fat from 97 to 99 per cent, and those for carbohydrates from 96 to 98 per cent. It is also noticeable that there is not any practical difference in digestibility of the diets with diflerent kinds of meat similarly cooked. Thus the average for the total diet in experiments with fat beef 43 shoulder cojked in water agrees closely with that for lean beef round similarly cooked; and in the experiments ^\dth lean beef round, beef ribs, veal, mutton, and pork, all roasted, the average coefficients range for protein from 95 to 97 per cent. These variations are smaller than some of those between the results for different indi- viduals wdth the same kind of meat. In brief, then, whether individual experiments or average figures be considered, differences in either the kind of meat or in the method of cooking the meat apparently had no decided effect upon the diges- tibiUty of the nutrients of the total diet used in these experiments. Digestihility of the meat alone. — The data in the last two columns of Table 20 show the coefficients of digestibility of the protein and the fat of the meat alone as distinguished from those for the corresponding nutrients in the total diet. These values were computed, in the man- ner described on page 26, from the data for total diet as directly deter- mined b}^ the experiments, by assuming certain factors for the digesti- bility of the nutrients of the foods eaten with meat. These factors are based upon the results of digestion experiments w4th such food mate- riids. It is, of course, not impossible that some error is involved in their iise in the present experiments, but whatever error there may be is believed to be small, and the computed coefficients of digestibilit)^ of the protein and fat of the meat alone are believed to be approximately correct. At any rate, since the same factors are applied to all experi- ments alike, the results computed by use of them are just as compara- ble wiih. each other as those determined for the total diet directly from the experimental data. It is possible, therefore, to judge from the figures in the table what was the effect of the different methods of cook- ing upon the digestibility of the nutrients of the meat alone. As regards protein, no effect seems to be indicated. The range in coefficients for the minor averages is from 97 to 100 per cent, and the average for all 44 experiments is 98 per cent. The agreement between results for individual subjects in similar experiments was correspond- ingly close in nearly every case, the chief exception being the results with subject A in the experiments with lean beef cooked in water for one and for two hours ; but in both of these sets of experiments the results with the other subjects agree closel}^ with each other. Considermg all the figures, both those for different subjects in sim- ilar experiments and the averages for the different kinds of experi- ments, the indications are that the protein of the meat was quite thor- oughh' digested, whether the same kind of meat was cooked in differ- ent ways or different kinds of meat were similarly cooked. The varia- tions for the different experiments are too small and too irregular to indicate any effect upon digestibilit}^ that may be ascribed to differ- ences in the kinds of meat used or in the methods of cooking. The same is true as regards fat, except in the case of lean beef cooked 44 in water. If these experiments be disregarded, the computed coeffi- cients for fat agree very favorably with each other in the minor aver- ages, the range being also from 97 to 100 per cent, and the general average for these 32 experiments being 99 per cent. The results with the different subjects in similar experiments also agree closely with each other with one exception — the coefficient for one subject with roast veal being 92 per cent, whereas those for the other five sub- jects ranged from 99 to 100 per cent. In the experiments with lean beef cooked in water, the calculated coefficients for fat are decidedly low, both in the case of meat cooked for one hour and in that of meat cooked for two hours. The average for the meat cooked for three hours is better, but there were only two of these experiments, in one of which the coefficient is high, and this raised the average figure. In the other of these two experiments, the coefficient is like those for meat cooked one hour. These low figures would at first appear to indicate that the fat of meat cooked in water was less thoroughly digested than that of meat otherwise cooked, but it is believed that such conclusions should not be drawn from these data. The low coefficients are more probably to be ascribed to slight inaccuracy in the assumed factors for digestibility of the fat of the foods other than meat. The quantity of fat in the meat in these particular experiments forms only a small proportion of the total fat of the diet, and where such is the case slight variations in the assumed factor for the fat of the other foods make relatively large difi^erences in the computed coefficients for the fat of the meat. It is very probable that if the proportion of fat in the meat used in these 12 experiments had been larger the coefficients would have been more like those for the meat used in the other experiments. This is indi- cated by the fact that in the 3 experiments with fat beef shoulder cooked in water two hours, in which the meat supplied a larger part of the fat of the diet, the coefficients for fat agree with those for meat otherwise cooked, and also by the fact that the fat of the total diet — that is, fat froiii all the food materials including the meat — was as thoroughly digested in these experiments as in the others. There seems, therefore, no reason for believing that the fat of the meat alone was any less thoroughly digested m these than in the other experi- ments. Considering all the experiments, it seems fair to assume from the data here summarized that about 98 per cent of the protein and 98 per cent of the fat of the meat were digested, and inasmuch as the simple diet used in these experiments was, as a whole, at least as thoroughly digested as the ordinary mixed diet, these data may be considered as representing the digestibility of the nutrients of meat eaten in combination with other common food materials. 45 Poda and Praiisnitz* studied the digestibility of roasted beef in a comparatively simple diet, and by making allowance for the digesti- bility of the additional food materials in the diet as previously esti- mated, they computed the digestibility of tiie meat itself. They found that 99 per cent of the protein of the meat was digested, which agrees with the figure given above for the average of the experiments here reported. Other investigators have reported experiments in which the diet included meat together with other food materials — for example, bread, which was the special object of study — and it would apparently be possible from the results of these to estimate the digesti- bility of the meat alone. A cursory examination of the results of some of these experiments indicates that the estimated digestibility of the meat would correspond with that obtained in the experiments here considered. But inasmuch as such estimates were not pre- viously reported by the investigators themselves, the work has not been summarized in the present publication for comparison. The investigation by Forster, mentioned on page 6, is of interest here, as the object was, like that of the experiments reported in the present bulletin, to determine the digestibility of meat cooked in different ways. He made 33 experiments in 7 series, in which dif- ferent cuts of beef were prepared as follows: (1) Raw, chopped, and flavored with salt, pepper, and onion; (2) cooked in butter, i. e., cut in slices 1 to 1.5 centimeters thick, sprinkled with s'alt and pepper, pounded, and fried for three to five minutes in a pan containing sufficient melted butter to cover the meat. Meat thus prepared was considered the most palatable of any used; (3) cut as in 2, and broiled (or roasted) for four minutes, with frequent turning in a closed, gas- heated grilling apparatus; (4) placed w^ith flavoring matters in cold water and boiled for one and one-half to two hours; (5) same as 4, save that the water at the start was at the boiling point; (6) soaked for two weeks in brine, removed twenty-four hours before use, soaked in water, and boiled; (7) salted as in 6, then smoked for three days, soaked in water, and boiled. In four series of experiments two cuts from the same animal were used, a cheaper one from the hind shank and a more expensive one from the shoulder. For the roasted meat only that from the shank was used,. and for the salted and smoked meats only the shoulder. The solid food consisted entirely of the meat, but beer or wine, to which all the subjects were accustomed, was allowed at meals. Two or more subjects were employed in each series, the author himself serving in all of them. The food and feces were weighed and anatyzed in the usual manner. The results obtained in these experiments are summarized by averages in Table 2 1 . ffZtschr, Biol., 42 (1901), p. 377. 46 Table 21. — Results of digestion experiments with meat alone. Kind of meat. Coefflcients of di- gestibility. Kind of meat. Coefflcients of di- gestibility. Protein. Fat. Protein. Fat. Hind quarter, raw, average of 5 experiments Per cent. 95.23 96.70 96.32 97.71 95.46 Per cent. 83.58 87.33 95.19 98.62 88.70 Shoulder, boiled, average of 4 experiments Per cent. 96.40 96.54 96.81 97.35 Per cent. 81.09 Shoulder, raw, average of 7 experiments Hind quarter, boiled, aver- age of 3 experiments Shoulder, pickled, average of 3 experiments 51.82 Hind quarter, fried in butter, average r f 2 experiments . . . 94.82 Shoulder, fried in butter, aver- age of 2 experiments Shoulder, salted and smoked, average of 3 experiments. . . 86.82 Hind quarter, broiled, aver- age of 4 experiments In these experiments the digestibiUty of the protein of the meat was m all cases quite thorough, and the results for the different sub- jects agree fairly well with each other. The averages for the experi- ments with meat cooked in different waj's range from 95 per cent with broiled meat to 98 per cent with meat fried in butter. In the average of all 33 experiments the digestibility of the protein was 90 per cent. This is a trifle lower than the average for the digestibility of protein of meat alone in Table 21 abov;e, but the difference is in- significant. The lower average in Forster's experiments is possibly due partly to the fact that meat formed the total food material, whereas in the experiments here reported meat was eaten in combi- nation with other common food materials. It has been commonly observed, as already explained, that a given food material may be more thoroughly digested when it is eaten with other food materials than when eaten alone. In view of this fact the figure for digesti- bility of protein obtained in the experiments here reported is believed to be supported by the results obtained by Forster in experiments such as his. Furthermore, the agreement in the results with meat cooked in different ways shows that the differences in the method of cooking had no effect upon the digestibility of the protein of the meat, which also supports the deduction drawn from the experiments reported in the present bulletin. As regards the digestibility of fat, most of the results obtained by Forster were noticeably lower than those found in the present experi- ments. In 3 cases among the average figures given in the table above the digestibility of fat ranged from 95 to 99 per cent, but in 5 cases the coefficients ranged from 81 to 89 per cent; and in 1 case it is as low as 52 per cent. These variations are so wide that the results are hardly to be considered in drawing deductions regarding the digesti- bility of the fat of meat cooked in different waj's. 47 DIGESTIBILITY OF THE NITROGEN (PROTEIN) AS CORRECTED FOR METABOLIC PRODUCTS IN THE FECES. The values for digestibility considered in the preceding discussion are those determined according to the usual custom, by analyzing the food and the corresponding feces in the same manner and deduct- ing the ingredients of the latter from those of the former. It is under- stood that this represents apparent rather than actual digestibility, because, as has been frequently pointed out, the feces do not consist entirely of undigested food. In fact they are composed in large part of the so-called metabolic products, which consist of residues from the digestive juices, epithelial debris from the nmcous lining of the intestines, etc. Some of these products contain nitrogen, which is of course included with that from the undigested food in the total nitro- gen of the feces as ordinarily determined ; and they also contain sub- stances that are soluble in ether and are extracted along with the undigested fat. To determine the actual digestibility of food it would therefore be necessary to separate the ingredients of the metabolic products from those of the undigested food. Various methods for making such separation, and thus affording means for determining the ingredients of undigested food, have been tried by different investigators, but no attempt has been made to summarize them here. It will suffice to say that none of the methods thus far proposed has proved entirely satisfactory. In connection with the digestion experiments with meat in a very simple diet reported in this bulletin, however, an effort was made to get some light upon the actual digestibility of the protein of the meat by follow- ing one of the common methods of removing metabolic nitrogen from the feces. This consists of digesting the feces with an acid-pepsin solution, on the assumption that this will dissolve the metabolic products containing nitrogen but will not affect to any appreciable extent the nitrogenous substances of the food that were not digested in the alimentary tract. The digestive solution used contained 1.25 grams of pepsin per liter of 0.33 per cent hydrochloric acid. The weighed sample of feces was placed in a flask with 100 cubic centimeters o^ this solution and kept for twenty-four hours at 38° to 40° C. The material in the flask was then filtered, and the residue was thoroughly washed and dried upon the filter paper. The top of the paper was then cut oft' to get rid of any soluble material dried there and the remainder containing the undissolved residue was dropped into a Kjeldahl flask and the nitrogen was then determined in the usual manner. The nitrogen in the material not dissolved by the pepsin solution was considered as pertaining to the protein of the food that escaped digestion, and the actual digestibility of the nitrogen was computed 466.3— Bull. 193—07 4 48 from the amount consumed in the food, and that thus determined for undigested material. These figures are summarized in Table 22. The coefficients thus obtained for digestibility of nitrogen are of course practically the same as for protein, since this is the onh' source of nitrogen in the food. In addition to the data for total diet, the actual digestibility of the protein of the meat alone has also been estimated. This was done by assuming that 2 per cent of the nitrogen of the milk and 5 per cent of that of the bread eaten with the meat would be accounted for in the undigested food residue. This factor for bread nitrogen was derived from the results of digestion experiments with bread by Woods," in which he computed the actual digestibility of the bread protein according to the same method as here followed for the meat. Table 22. — Metabolic nitrogen in feces as determined by treatment with pepsin solution, experiments Nos. 290-301, 368-387, 419-430. Ex- peri- ment No. Sub- ject. Kind of food. Nitro- gen in food. Air- dried, feces.' Nitrogen in total feces. Nitrogen in feces undis- solved by pep- sin solution. Nitrogen di- gested. 290 A B B A B A B D E B E B E E B Beef, bread, butter: Entire diet Grams. 3t).09 28.95 48.44 38.73 46.75 40.32 34.51 26.92 38.55 32.24 25.83 16.42 33.24 21.70 60.57 43.90 85.68 51.66 61.86 44.28 76.54 50.48 64.92 46.09 70.47 50.05 72.85 50.65 64.31 54.27 Grams. 43.38 Per ct. 6.32 Gi^ms. 3.03 2.02 1.68 .74 1.30 .36 3.03 1.30 1.13 .20 .82 Per ct. 2.88 2.39 2.14 2.71 2.22 2.14 Grams. 1.39 1.03 .92 ..52 .51 .13 1.05 .66 .60 .27 .38 Grams. 34.70 27.92 47.52 38.21 46.24 40.19 33.46 26.26 37.95 31.97 25.45 16.42 32.87 21.70 60.22 43.90 84.79 51.66 61.01 44.02 75.83 50.48 64.34 46.09 64.41 50.26 72.02 50.49 63.74 54.08 Per ct. 96.07 96.44 291 Beef, bread, milk: Entire diet Meat alone Beef, bread, butter: Entire diet Meat alone Beef, bread, butter: Entire diet Meat alone Beef, bread, butter: Entire diet Meat alone Beef, bread, butter, milk: Entire diet Meat alone. . . .' Beef, bread, butter, milk: Entire diet Meat alone Beef, bread, butter, milk: Entire diet Meat alone Beef, bread, butter, milk: Entire diet Meat alone Beef, bread, butter, milk: Entire diet Meat alone Beef, bread, inilk: Entire diet Meat alone Beef, broad, butter, milk: Entire diet .38.29 4.49 98.10 98.66 292 23.98 5.44 98.90 99.67 293 38.75 6.21 96.96 97.55 294 27.10 4.17 98.44 99.16 295 18.04 4.52 98.53 100.00 206 18.85 4.41 .83 2.01 .38 98.89 100.00 297 21.50 4.39 .94 .46 2.90 .99 1.87 ..54 2.51 1.24 1.79 .76 2.98 1.52 2.98 1.64 1.96 1.05 1.63 .35 99.42 100.00 298 62.05 4.68 1.43 .89 98.96 100.00 299 52.00 3.60 1.63 1.27 .85 .26 .71 98. 63 99.41 ;io() .55.60 4.51 99.07 100.00 301 37.01 4.77 l.,54 .58 99.11 100.00 368 Beef, bread, butter, milk: Entire diet Meat alone Beef, bread, milk: Entire diet Moat alone Beef, bread, milk: Entire diet Meat alone 75 . 76 3.94 1.40 1.24 1.41 1.06 .39 .83 .16 .57 .19 98.50 99.23 3(19 67.32 4.43 98.66 99.68 370 40.76 4.82 99.11 99.66 aJJ. S. Dept. Agr., Office of Experiment Stations Buls. 85 and 143. 49 Table 22. — Metabolic nitrogen in feces as determined by treatment with pepsin solution, experiments Nos. 290-301, 368-387, -^/S-^-SO— Continued. 371 Ex- p:ri- I Sub- mcnt ject. No. E E H H B H B B Kind of food. Nitro- . gen in food. Beef, bread, butter, inilk: Entire diet Meat alone Beef, bread, milk: Entire diet Meat alone Beef, Ijread, milk: Entire diet Meat alone Beef, bread, butter, milk: Entire diet Meat alone Beef, bread, milk: Entire diet Meat alone Beef, bread, milk: Entire diet Meat alone Beef, bread, butter, milk: Entire diet Meat alone Beef, bread, milk: Entire diet Meat alone Beef, bread, milk: Entire diet Meat alone Veal, bread, milk: Entire diet Meat alone Mutton, bread, milk: Entire diet Meat alone Veal, bread, butter, milk: Entire diet Meat alone Veal, bread, butter, milk: Entire diet Meat alone Mutton, bread, butter, milk: Entire diet Meat alone Mutton, bread, butter, milk: Entire diet Meat alone Pork, bread, butter, milk: Entire diet Meat alone Pork, bread, butter, milk: Entire diet Meat alone Veal, bread, milk: Entire diet Meat alone Veal, bread, butter, milk: Entire diet Meat alone Veal, bread, butter, milk: Entire diet Meat alone Beef ribs, bread, but- ter, milk: Entire diet Meat alone Beef ribs, bread, but- ter, milk: Entire diet Meat alone Air- dried faces. Grains. Grams. 7:3.91 I .59.83 50.09 82.11 .54.6.5 40.52 70.56 42.18 54.65 Nitrogen in total feces. Per ct. 4.80 69.27- 43.48 71.60 48.92 61.93 38.05 81.47 ,57.16 70.20 47.63 77.42 57.10 79.52 58.50 73.40 49.62 101.18 71.99 69.39 53. 99 92.57 62. 38 80.20 51.05 90.43 56.01 79.05 50.91 72.17 45.41 79.05 49.95 67. 36 45.41 67.47 35. 27 54.26 65.63 42.21 ;i5.01 :i5.04 27.78 45.56 73.85 56.00 34.42 72.12 53.29 39.69 44.73 39.79 25.73 26.87 59.48 65.45 I 60.97 35.27 5.59 4.39 4.56 4.86 3.36 4.56 4.94 Grams 2.87 1.23 2.27 .36 1.85 .95 2.47 .88 3.19 1.96 Nitrog'n in feces undis- solved by pep- sin solution. Per ct. 2.18 1.&3 2.00 3.64 6.47 5.12 6.10 4.61 4.89 3.41 5.16 3.81 5.35 3.99 3.52 3.40 1.42 .36 1.59 .32 1.73 .69 1.01 .02 2.95 1.87 3.78 2.36 3.42 1.14 1.59 .53 3.53 1.32 1.82 1.94 1.77 1.54 2.09 1.63 1.32 2.05 1..54 Grams. 1.30 .53 .74 2.29 1.93 1.47 2.05 .03 1.70 2.13 .60 1.03 .94 2.02 2.90 1.77 1.44 1.75 1.42 1.26 1.14 1.28 .94 .84 .38 1.05 .27 1.16 .51 .65 .03 .73 .05 .57 .37 .94 .35 1.14 .42 1.28 .28 .66 .17 1.06 .05 .77 .69 .64 .50 .29 .34 .53 .57 Nitrogen di- gested. Grams. 72. (.1 49.56 81.37 54.65 09.72 54.27 68.22 43.21 70.44 48.41 ■61.28 38.02 80.74 57.11 69.63 47.63 77.05 57.16 78.58 58.15 72.26 49.20 99.90 71.71 68.73 53.82 91.53 62.33 79.43 51.05 89.74 56.01 78.41 50.91 71.67 45.41 78.76 49.95 67.02 45.41 66.94 35.27 64.88 35.27 Perct. 98.24 98.24 99.10 100.00 98.81 99.30 98.48 99.38 98.38 98.99 98.95 99.92 99.10 99.91 99.19 100.00 99.52 100.00 98. S2 99.40 98.45 99.15 98.74 99.61 99.05 99.69 98.86 99. 92 99. 04 100.00 99. 24 100. 00 99. 19 100. 00 99. 31 100. 00 99.63 100. 00 99.50 100. 00 99.21 100. 00 99.13 100.00 50 Table 22. — Metabolic nitroyeii in feces as determined by treatment with pepsin soluHon, experiments Nns. JDO-SOl. 368-387, ilH- Ex- peri- ment No. Sub- ject. 424 I 425 J 426 B 427 J 428 1 429 B 430 J Kind of I'oQil. Ham, bread, butter, milk; Entire diet Meat alone Ham, lircad, butter, milk: Entire diet Meat alone Beef ribs, bread, but- ter, milk: Entire diet Meat alone Beef ribs, bread, but- ter, milk: Entire diet Meat alone Beef ril).9, bread, Init- ter, milk: Entire diet Meat alone Beef rilis, bread, but- ter, milk: Entire diet Meat alone Beef ril)s. bread. Ijut- ter, milk: Entire diet Meat alone Nitro- gen in food. Gram.i. (32. (12 40.21 69.10 41. 70 72. 36 43. 36 84.85 59.14 54.73 36. 19 67.98 41.59 85.16 60.49 Air- dried feces. Grams. 28. 70 Nitrogen in total feces. Per cl. 4.79 43. 25 51.62 25. 62 38.30 23.35 56.18 4.96 2.85 Nitrogen in feces undis- solved by pep- sin solution. Grams. Per ct. 1.38 i 1.71 .06 I 2.14 .21 1.46 3.09 4.20 4.74 5.64 1.02 1.61 .37 1.11 :117 Iv25 Grams. a 49 1.04 1.39 1.27 2.35 1.62 .45 .50 .36 .49 .55 .91 .06 Nitrogen di- gested. Grams.'' Per cl. 62. 13 j 99. 22 40.21 ' inn.no 68.65 : 99.35 41.76 j 100.00 71. 86 ; 99. 31 43.36 100.00 84.49 I 99.58 59.14 I 100.00 54.24 36.19 67.43 41.59 84.25 60.43 99. 10 1(K). 00 99. 19 100. 00 98.93 99.90 The above data are summarized in Table 23, the results for similar experiments being brought together and averaged. Tablk 23. — Coefficients of digestibility of protein after correction for metabolic products. Ex- peri- Sub- ment ject. No. 293 A 294 B 297 D 300 E 301 B 290 A 291 B 292 B 298 E 299 B 295 A 296 B ' 371 F 372 E 373 B 374 F 375 E 376 B Kind (if moat. Lean beef round, cooked in waterat 80° to 85° C. for 1 hour. ....do ....do ....do ....do Average Lean beef round, cooked in water at 80° to 85° C. for 2 hours. ....do ....do ....do ....do Average Lean beef round, cooked in water at 80° to 85° C. for 3 hour^ ....do .\verage. Lean beef round jian broiled ....do ....do Average Lean beef round fried in hot lard do do Average . Protein digested in- Total food. Meat alone. Per cent. 96. 96 98.44 99.42 99.07 99.11 98.60 96.07 98.10 98.90 98.96 98.63 Per cent. 97.55 99. 16 100.00 100. 0(J 100. 00 99.34 96.44 98. 66 99.67 100.00 99.41 98.13 98.84 98.53 98.89 100.00 100.00 98.66 100.00 98.24 99.10 98.81 98.24 100.00 99.30 98.72 99.18 98.48 98.38 98.95 99.38 98.96 99.92 98.60 99.42 51 Table 23. -Coefficients of digestibility of protein after correction for iiietaholir products- Continued. Ex- Sub- ject. Kind of meat. Protein digested in- peri- ment No. Total food. Meat alone. 377 378 F E B F E B I B B J B B J n I B II I B H I B I B I J Lean beef round roti sted do Per cent. 99.10 99.19 Per cent. 99. 91 inn.no 379 do 99. 52 100. 00 Average 99.27 99.97 Fat beef shoulder cooked in water at 80° to 85° C. for 2 hours do 3t)8 359 98. .50 98.86 99.11 99.23 99. 68 370 do . . 99.65 Average 98.82 99.52 Beef ribs roasted 422 99.21 99.13 99.31 99.58 99.10 99.19 98.93 100. 00 423 do 100. 00 42(; do . . . 100. 00 427 . .do 100. 00 428 do 100. 00 429 do 100. 00 4.30 . ..do 99. 90 99.20 99. 99 Veal leg roasted do 380 382 98.82 98.74 99.05 99.31 99.03 99.50 99.40 99.61 383 do 99. 69 419 do ... 100. 00 420 ..do 100. 00 421 do 100. 00 Average 99.18 99. 7S Mutton leg roasted . .... 381 98. 45 99. 15 384 .. ..do 98.86 ' 99.92 385 do 99.04 100. 00 Average 98.78 99.69 Pork, fresh ham, roasted do 386 387 99.24 99.19 99.22 99.35 100. 00 100. 00 424 do 100. 00 425 do ... 100. 00 Average .* 99.25 100. 00 The actual digestibility of the protein of the total diet and of the meat alone, as shown by the figures in Table 23, is high. The figures for meat alone would indicate that practically all of the protein of the meat was digested. This is not at all improbable, though it should be stated that severe criticism of the method by which the data were derived would suggest that such a conclusion can not be drawn without some qualification. It is not certain that the pepsin solution, even though very weak, would digest only the nitrogenous materials from the metabolic products of the feces, and leave all of the undigested food protein unaffected; possibly some of the latter might be dissolved also. Furthermore, it is possible that the undi- gested meat protein would be more affected than that from bread, as experiments indicate that artificial digestive solutions act more readily upon the former than upon the latter. Nevertheless, the authors are inclined to believe, in the light of results obtained in artificial digestion of meat, that the results shown in Table 23 are not far from the truth, and that the actual digestibility of meat pro- tein is near 100 per cent. 52 INCOME AND OUTGO OF NITROGEN AND GAIN OR LOSS OF PROTEIN. In each digestion experiment tlie urine of the subject was collected for each twenty-four hours, and the quantity of nitrogen in it deter- mined b}' the Kjeldahl method. At a certain hour on the first day of each experiment the urine was voided and rejected, then all that was eliminated up to the same hour the next day was collected for the day's output. In most of the experiments the urine periods began at 7 a. m., but in experiments Nos. 275 to 282 they began at 1 p. m. In each case the final period ended at the corresponding hour on the first day following the experiment. In experiments Nos. 284 to 289 the urine was collected in six-hour periods, and the nitrogen in it determined for each period. The urine data for the different exoeriments are o-iven in Table 24, showing the total weight of urine for each day and the percentage and amount of nitrogen in it, except that in experiments Nos. 284 to 289, in which the determinations were made in six-hour periods, the percentage of nitrogen in the daily urine is not given, the total weight of urine and quantity of nitrogen for the day being the sums of the corresponding data for the six-hour periods. The table also shows the total quantity of nitrogen in the urine, in the feces, and in the food for each experimental period, and the apparent gain or loss of nitrogen and protein by the body, the protein being computed from the estimated gain or loss of nitrogen in the usual manner, by multiplying by the factor 6.25. Table 24. — Quantity and. nitrogen content of urine per day, total income and outgo oj nitrogen, and apparent gain or loss of protein, in experiments Nos. 267-301, 368-8^7^ 419-429. ■4-J 8 3 cc A B A Kind of food. oB =» S ^^ ft f 1 ^4 Weight urine. Quantity of nitrogen in Total quantity of nitrogen in— Apparent gain (+) or loss {—■■ to body. dail.y urine. Urine. Feces. Food. Nitro- gen. Pro- tein. Mixed diet, including lean heef pan l)roiled. Grams. 871.1 693.5 713.8 688.6 Pr. ct. Grams. 1.43 1 12.46 Grams. Grams. Grams. Grams. Grams. 267 1.69 1.67 1.62 11.72 11.92 11. .32 i Total •••• Mixed diet, including ., lean beef pan l)roiled. •' X 4 Tolal 2,977.0 47.42 3.92 47.80 -3.54 —22.13 645.0 8.30.3 831.1 862.2 1.94 12.51 l.Gl 13. 4G l.CO 1 13.80 1.62 ! 13.97 268 * 2,594.1 1 53.74 4.36 63.84 + 5.75 + 35.95 269 Mixed diet, including ( 1 lean beef pan broiled. < 2 648.9 768.3 769.5 1.53 1 9.93 1.40 1 10.76 1.33 10.34 Total l3 2,186.7 1 31.03 2.82 34.50 + .74 + 4.63 53 Table 2i.— Quantity and nitrogen content of urine per day, total income and outgo of nitrogen, and apparent gain or loss of protein, cfc— Continued. ' ' 1^ ' 1 3 B A B A B B B 3 B B B Kind of food. E 03 P P 1 3 Weight of urine. Quantity of nitrogen in daily urine. Total quantity of nitrogen in— Appar nt gain ( + ) orloss(-) to body. a. Urine. Feces. Food. Nitro- gen. Pro- tein. 270 Mixed diet, including lean beef pan broiled Total Grams. 748.4 666.. 5 835.2 Pr.ct 1.70 1.58 1.71 Grams 12.72 10.53 14.28 Grams Grams. 1 Grams 1 1 . Grams Grams. 1 2,250.1 37.53 3.09 47.77 + 7.15 + 44.69 Mixed diet, including lean beef cooked in water '^ hnni*^ f 1 J 2 1 3 I 4 271 644.1 916.2 680.8 793.2 3.034.3 1.33 1.15 1.60 1.46 8.57 10.54 10.89 11.58 • Total 41.58 3.96 51.59 +6.05 +37.81 Mixed diet, including lean beef cooked in water 2 hours Total f 1 2 1 3 I 4 272 735.9 739.3 726.8 917.1 1.22 1.46 1.61 1.57 8.98 10. V9 11.70 14.40 3,119.1 45.87 2.96 66.48 + 17.55 + 110.32 Mixed diet, including lean beef cooked in water 4 hours Total 1 J 2 1 3 I 4 2;3 809.4 693.0 630.3 747.4 1.23 1.55 1.66 1.54 9.97 10.74 10.46 11.51 2,880.1 42.68 2.eo 49.31 + 4.03 Mixed diet, including lean beef cooked in water 4 hours Total 1^ I 4 + 25.19 2;4 804.2 805.4 803.5 755.0 1.38 1.47 1.62 1.89 11.10 11.84 13.02 14.27 3, 168. 1 50.23 2.55 64.46 + 11.68 Mixed diet, including lean beef cooked in water 2 hours Total f 1 2 3 , 4 + 73.01 2io 1,203.6 821.3 1,219.8 1,149.7 1.29 1.93 1.48 1.22 15.53 15.85 18.05 14.03 4, .394. 4 63.46 3.53 59.40 -7.59 Mixed diet, including lean beef cooked in water 2 hours Total f 1 2 3 . 4 — 47.40 Aib 797.8 846.2 924.0 1,607.4 1.88 1.93 1.79 1.01 15.00 16.33 16.54 16.24 4,175.4 64.11 4.79 63.41 -5.49 -34.30 Mixed diet, including lean beef cooked in water 2 hours Total Mixed diet, including lean beef fried Total Mixed diet, including lean beef fried Total f 1 2 3 4 1 2 3 4 1 2 3 4 m 757.4 866.3 93S.6 849.9 1.92 1.87 1.73 1.83 14.54 16.20 16.24 15.55 -. 3,412.2 62.53 2.50 57.07 -7.96 -49.80 1 278 785.5 858.5 855.3 825.5 1.89 1.75 1..59 1.69 14.85 15.02 13.60 13.95 3,324.8 57.42 2.02 53.45 -5.99 -37.40 1- !79 770.8 846.8 954.1 862.5 3,434.2 ■ 1.55 1.64 1.45 1.49 11.95 13.88 13.84 12.85 52.52 1.57 52.54 -1.55 Mixed diet, including lean beef cooked in water 20 minutes ■ Total 1 2 3 4 —9.65 80 661.4 1,044.2 997.6 884.8 1.S4 1.45 1.29 1.60 12.26 15.14 12.87 14.16 3,588.0 . 54.43 2.93 53.56 -3.80 = : — z —23.80 54 Tablk 24. — Quantity and nitrogen content of urine per day, total incouie and outgo of nitrogen, and apparent gain or losn of protein, etc.. — Continued. 4-> g .16 o a 1 B B C C C c c c A B Kind of food. I ■"a (d ft Q Weight urine. Quantity of nitrogen in daily urine. Total quantity of .^PP^^/^i^* ^f °. nitrogen in- ^ + Nobody ft Urine. Feces. Food. Nitro- gen. Grama. Pro- tein. 281 Mixed diet, including lean beef cooked in water 20 minutes Total it Grams. 779.5 908.5 1,0.52.8 796.9 Pr.ct. 1.55 1.62 1.41 1.71 . Grams. 12.08 14.72 14.84 13.63 Grams. Grams. Grams. Grains. 3,537.7 \ 55.27 1.76 57.12 4- nt) [ 4- 5fi Mixed diet, including lean beef cooked l)y broiling 20 minutes.. . Total 1 2 \ 3 I 4 282 792.4 1,054.3 901.0 792.9 1.37 1.28 1.37 1.51 10.86 13.50 12.34 11.9? 1 ' 3, .540. 6 1 48.67 3.3i 49.43 —2 55 i5 94 Mixed diet, including lean Ijeef cooked in water 2 hours Total 1 2 1 3 I 4 284 784.5 1,380.3 1,174.2 1,296.2 13. 59 1/.91 16.82 16.77 ! 4,635.2 65.09 7.48 74.86 +2.29 +14 32 Mixed diet, including lean lieef cooked in water 2 hours Total f 1 4 285 • 789.7 782.0 903.6 837.3 16.07 17.69 19.93 18.09 1 3,312.6 71.78 4.80 74.19 -2.39 1 -14.94 Mixed diet, including lean beef cooked in water 2 hours Total f 1 2 3 4 5 ?Sfi 1,515.1 1,047.9 972.8 1,051.7 393.8 i.'is' 13.44 15.55 16.21 17.09 4.45 4,981.3 66.74 6.82 82.. 53 + 8.97 1 +56.05 Mixed diet, including lean beef cooked in water 2 hours Total 1 2 3 4 287 1,228.5 1,310.0 1,250.5 1,060.5 16.65 16.58 16.69 16.06 1 1 _ 4,851.5 65.98 7.84 77.17 + 3.35 +20.94 Mixed diet, including lean beef coolced in water 2 hours Total f 1 2 3 . 4 288 912.7 839.3 756.5 854.3 '.".". 14.26 15.59 15.68 16.46 3,362.8 61.99 5.88 67.68 -.19 — 1.19 Mixed diet, including lean beef cooked in water 2 hours Total f 1 2 3 . 4 289 822.9 848.8 873.0 934.2 15.98 16.19 17.23 16.15 3,478.9 65.. 55 5.40 68.36 -2.59 —16.18 Simple diet, including lean beef round, cooked in water at 80-85° C. for 1 hour. . . Total [l 293 884.6 922.7 1.85 2.03 16.37 18.73 1,807.3 35.60 3.03 34 51 -3.62 -11.38 Simple diet, including lean iieef round, cooked in water at 80-85° C. fori hour... Total 1 1 \2 294 994 2 995 3 1.61 1.96 16,01 19.51 1,989.5 35.52 1.13 38.55 + 1.90 + 5.94 55 T\iii,io ■lA.—QuaiUUy and nitrogen conlenL of urine per day, total income and outgo (/ nitrogen, and apparent gain or loss of protein, etc. — Continued. 4-3 a a) 1° 1 D E B A B B E B A B Kind of food. Weight Quai nitre itity of )gen in ■ urine. Total quantity of nitrogen in— Apparent gain (+ ) or loss (-) to body. a, urine. ' daih Urine. Feces. Food. 1 Nitro- gen. Pro- tein. 297 Simple diet, including lean beef round, cooked in water at 80-85° C. fori hour... Total {l Grams. Pr.ct. 959.2 i 1.29 1,083 I 1,98 1,183.0 , 2.23 Grams. 12 37 21.46 26.38 Grams. Grams. Grams. Grams. Grams. 3,225 8 60 21 94 60 57 -0.58 - 1.19 Simple diet, including lean beef r o u n d, coolced in water at 80-85° C. fori hour... Total [l 300 1,173.0 1,361.1 1,260.1 1.53 1.81 2.04 17.95 24,64 25.71 1 3, 794. 2 68 30 2.51 76.54 +1.91 + 11.94 Simple diet, including lean beef round, cooked in water at 80-85° C. fori hour... Total il 301 1,094 4 1,112 9 1,009.1 3,276 4 1 1.51 1.96 2 05 16 53 21.81 21 92 60 26 1 79 1 Rd 09 + .96 + 6 00 Simple diet, including lean beef round, cooked in water at 80-85° C. for 2 hours.. Total i 1 12 290 823,6 1,134 2 2 04 1.06 16 80 18.83 1,957.8 35 63 3 06 36 08 -1.31 - 8 19 Simple diet, including lean beef round, cooked in water at 80-85° C. for 2 hours.. Total [1 291 1,083 3 1, 166 3 1.60 2 05 17 33 23 91 ' 2, 249 6 41.24 1. 68 1 48 44 + 2 76 + 17.25 Simple diet, including lean lieef r o u n (1 , cooked in water at 80-85° C. for 2 hours. . Total a 292 1,165 5 1,078 6 1.76 2 04 20 48 21.94 ' 2,244 1 42.42 1.30 46 75 + 1.51 + 9.43 Simple diet, including lean beef round, cooked in water at 80-85° C. for 2 hours. . Total If 298 1,259 4 1,314 4 1,350 2 1 79 1 99 2 01 22 54 26 16 27.14 3, 294 75 84 2 90 85 68 +2.31 + 14 44 Simple diet, including lean beef round, cooked in water at 80-85° C. for 2 hours.. Total li 299 884 9 927 3 980 1 1.78 2 10 2 15 15 75 19 47 21.07 r 2, 792 3 56 29 1.87 61.88 + 1.23 + 7.69 Simple diet, including lean beef round, cooked in water at 80-85° C. for 3 hours.. Total {I 295 Lost. 936 8 1.75 16 39 .82 25 83 -3 89 94 31 Simple diet, including lean beef round, cooked in water at 80-85° C. for 3 hours.. Total [1 296 774.0 810 8 2 03 2 24 15 71 18 16 1,584 8 33.87 .83 j 33. 24 - .74 4 63 ou Table 24. — Quantily and nitrogen content of umie per day. total income and outgo of nitrogen, ai\d apparent gain or loss of protein, etc. — Continued. t;,° " 3n Kind of food. g^ I Total quantitv of M^^'l^^^.ti'? -i Weight Quantity of; nitrogen in— to bod v E of nitrogen in ' cc Urine. Feces. Food. Nitro- I Pro- gen. tein. Simple diet, including Grams. Pr.it. Grams. Grams. Grams. Grams. Grams. Grams lean beef round, fl; 8S0 9 100 14 19: ' 372 E pan broiled {2 l,o40 2 1. 9a 25 98 t9 [ 3 l,li;.S 1 2C3 22. Total 3.350.9 62 SO 73 91 73 -17.00 Simple diet, including lean beef round, f 1 ] 1,410.7 1.80 1 25 39 pan broiled n' 2 1.005 2 04 1 20 50 1 3 l,2iS 3 2.20 I 26 80 Total 3,634.0' - 72 69 2 27 82.11 +2.SS -14.87 373 574 : F Simple diet, including ' P lean beef round, f 1 ' 1.179.1 panbroiied \2 1,1562 I 3 , 1,0,>2 7 1.87 1 22 05 2 17 25 09 2 17 ' 22 41 Total 1 I S,36S . 69 55 1.85 70. 56 - . 28 - 1. 75 Simple diet, including lean beef round, 11 1.267.7 i 1.45 18 38 fried in hot lard {2 1.100.6.1.8^1 2124 I 3 , 1,000 5 2 0.- 20 71 Total ' 3.42S S »00 2 47 ; C9.27 -i-2 10 -M3.50 375 ' E ' Simple diet, including lean beef round, I 1 1 1,339.8 1 67 22 S8 fried in hot lard \ 2 1,200 8 I 1.93 l 24 io [ 3 95..S ' 2 11 I 20 21 Total i 3,564.4 67.04 376 B Simple diet, including I | lean beef round. [1 1.0S3-2 I 1.66 ■ 17 98 fried in hot lard \ 2 1,103.4 , 2 OD 1 22 0/ I 3 I 1.134.1 2 CO 23 36 Total I 3,320 63 41 377 F Simple diet, including lean beef round, f 1 roasted ■! 2 3 1,297.8 I 1 68 21 79 1.325.5 ' 1 9jJ 25 58 1.321.6 2 03 I 26 43 3.19 71. 60 I -1- . <6 -4- 2 88 1.42 ; 61.93 I -}- .97 - 6 06 Tot.al. 37S E Simple diet, including j le.in beef round. (1 roasted -S5' C. for 2 hours-. \ 2 [3 920 9 2 r^ 97S0 2 : 9C9 4 2 1. Total .---! 2. 3l- 60 34 2 9S 369 I E I Simple diet, including fat beef shoulder, cooVed in water £t aK«s5 I in water £t f 1 ' 918 9 i 2 IS 20 03 C. for 2 hours.. \ 2 ; 1,099 5 ' 2 16 23 75 ; I 3 I SSS 6 2 2S 20 26 70 47 +2 C9 4-14 94 Total '--..| 2,907.0 64.04 2^ 72. So -^1.94 +12.13 57 Table 24. —-Quantihj and nitrogen content of urine per day, total income and outgo of nitrogen, and apparent gain or loss of protein, etc. — Continued. a a7 -4^ 2 3 «2 B 1 1 1 i I B B J Kind of food. Weight of Quantity of nitrogen in Total quantity of ' APfo^'loss?'"^ mtrogenin- ; (+>t^Vo|y.^~^ >>fe urine. OS a daily unne. Urine. . Grams ' Feces. Food, j Nit-- Pro- tein. 370 Simple diet, including fat beef shoulder, cooked in water at 80-85° C. for 2 hours. Total ; Gravis. f 1 1,102.9 Pr.ct: Grams 1. 85 ; 20. 40 2, 26 i 22. 49 2, 36 20. 48 . Grams 1 1 [ ! Grams., Grams. Grams. u 995 1 867.7 . ..:::;;:i::::::: :: """1 1 j .... 2,965 7 ! 63 37 1 aa 64.31 -0 34 -5.13 Simple diet, including beef ribs, roasted. . . Total 1 422 1,176 9 1,046 3 918 9 1. 87 I 22 01 1. 84 i 19 25 1.94 17.83 1 1 1 1 f , 1 3,142.1 59 09 2. 02 67.47 + 2.12 +13.25 Simple diet, including beef ribs, roasted Total \l 423 996 3 1,029 5 1,099 5 1.88 2 12 1.81 18 73 21 83 19 90 1 1... i i 3, 125 3 60.46 1.77 65.45 +1.07 + 6.69 Simple diet, including beef riVis, roasted .... Total 426 1; !,!94.0 1 1 76 1,164 5 1 88 21 02 21.89 1 j 1,115 1 2.03 j 22 63 1 3, 473. 5 65 54 1. 46 72 36 i +1.79 + 11.19 Simple diet, including beef ribs, roasted Total 427 (l.-i 1,524 4 1.53 i 23.32 ■ 1 . {t 1,536 3 1,592 7 1.65 1.73 25 35 27.55 ; 1 ■ ■ ! """! I B J H I B n 1 4,653 4 76.22 1.02 84,85 ; +2.54 + 15.88 Simple diet, including beef ribs, roasted Total 428 13-- 843 897 5 940 4 1.96 2.01 2.08 16 52 18 58 19 57 2,680 9 54 67 1.61 54 73 - . 52 - 3.25 Simple diet, including beef ribs, roasted Total 429 1; 1,118 6 1,053 988 1 78 2 02 2 14 19 13 21 27 21.14 1. 1 • i 3,159 6 61 54 1 1 11 Simple diet, including 430 (1-- 1,226 7 1,305 6 1.715.9 1 88 1.95 1.54 23 06 25 50 26 43 : !.... 1 beef ribs, roasted '{2.. ' 1 Total 13.. 1 i 4,248 2 74 99 3.17 85 16 +2.33 + 14.56 Simple diet, including veal leg, roasied Total 1 Simple diet, including veal leg, roasted Total 380 1; 978 5 1,361.1 1,240 6 2 22 2 18 2 31 21 72 29 67 28.66 1 i . ' i - : , I ' 1 ■ ! 2, 580 2 80 05 j 2 95 79.52 -1.16 - 7.25 382 1; 1,315 1 2 06 1,288 2 09 1, 480 2 2. 27 27 09 26 92 33.60 1 ; 1 r _ ^ .... 1 4,083 3 87.61 3.42 101.18 1 +3. £8 +21. 13 Simple diet, including veal leg, roasted 1 Total 383 1; 1,090 3 1,180 2 1.81 2 00 19 73 23.61 24 38 1 1, 177. 9 2 07 3, 448 4 1 67.72 1.59 69 S9 + .03 + .19 Simple diet, including veal leg, roasted L Total 419 It. 3.. 972 995.7 1, 152. 5 2 19 2 23 2.35 21 29 22 20 27 C9 1 .......1 3, 120 2 70. f 8 2 13 1 72 17 - .18 - 1.13 Simple diet, including veal leg, roasted < Total 420 Il- ls:: 1,246.4 1,040.9 1,115.0 2.04 2.20 2.17 25 43 22 90 24 20 3, 402. 3 72.53 1.03 79.05 1 : 58 Tarlk 24.--Quant/ity and nitrogen content of urine per day, total income and outgo oj nitrogen, and apparent gain or loss of protein, etc.— Contimiod. § $6 3Z ! Iviiui of food. Simple diet, including veal leg, roasted Total •^ " \\'cight >.^ urine. Quantity of nitrogen in daily urine. Tot; 1 quantity cf ! Apparent gain irclgeninl ;(+) ^bo^d^.^-^ =■1 S Urine. Grams. Feces. Food. Nitro- gen. Pro- tein. 421 B H I B I B I J Grams. |1.- 1,004.8 Pr.ct. 1.90 Grams. 20 23 22 50 24.52 j Grams. Grams. \ Grams. Grams. ^2.. 1,13C.4 l3.. 1,184.4 1.98 2.07 3,385 6 67. 25 0.94 67.36 -0.28 - 1.75 Simple diet, including mutton leg, roasted.. 381 fl.. 905 8 ■^2... 1,182 5 2 27 2.18 2.15 20 56 25 78 24.78 3.. 1,142 9 Tota 1 3,231.2 70.91 3.78 73.40 - .43 - 2.69 Simple diet, including muttoii leg, roa.sted.. Total 1; 3S4 1,236 1,481.5 1,329.5 2 12 1.98 2 03 26 20 29 33 26.99 i 1 1 t 4,047.0 82.52 3.53 1 92.57 4-2 17 j-i-a Kft Simple diet, including, nuitton leg, roasted. . Total 385 1; 1,110 1 1,266 5 880.7 1 64 1.88 1.95 18.21 23.81 17.17 3,257.3 59.19 1.82 80.20 -Lft 40 i -1-40 00 Simple diet, including pork (fresh ham), roasted 386 i;; 1,121.3 1,258 2 1, 132. 2 2.18 2 23 2.25 24,45 28 06 25. 45 », Total 1 3,510.7 77.96 2.05 90.43 +3.47 +21.69 Simple diet, including pork (fresh ham), roasted Total 387 1; 1,196 7 1,248 7 1,083.1 1.91 2 06 2.11 22.86 25 72 22.85 1 1 3,528.5 71.43 1.70. 79.05 + 1.97 j +12.31 Simple diet, including pork (fresh ham), roasted 424 1; 1,253.4 1,030 3 932.2 1.63 2 22 2 37 20.43 22 87 22.09 - ! . 1 Total 1 r.'^Miu 65.39 1.38 62.62 - .47 - 2.94 Simple diet, including pork (fresh ham), roasted Total 425 i;; 1,332 6 1,542.3 1,511.1 1.41 1 31 1.42 18.79 20.21 21.46 4,386.0 60.46 2.14 69.10 +2.17 4 13. 56 No definite conclusion regarding gain or loss of protein can be drawn from the above data, because nothing was known concerning the diets and the income and outgo of nitrogen of the subjects previous to the beginning of the experiment; hence it is impossible to tell to what extent the nitrogen of the urine collected pertains to the food of the experimental period and how much should be ascribed to food eaten previous to the experiment. Furthermore, the lag in the excre- tion of nitrogen from the experimental diet might extend beyond the time of ending the last urine period. For these reasons the difference between income and outgo of nitrogen has been designated "apparent" gain or loss in the above table. It is believed, however, in the light of present available knowledge concerning the lag in nitrogen excretion, 59 that the data for the second and third days of the experimental periods' show with some approximation to accuracy the actual balance between income and outgo of nitrogen under the conditions of the experiments, and from these some estimate can be formed regarding the balance for the whole period. The gains and losses were very fluctuating, and there were some noticeable losses and some decidedly large gains of nitrogen. On the whole, the gains were much more numerous than the losses, and the average amount gained was so much greater than that lost that it seems fair to assume that the diets used in the experiments were at least sufficient to supply the needs of the subjects for nitrogen. INVESTIGATIONS ON THE EASE OR RAPIDITY OF DIGESTION OF MEAT. The ease or rapidity with wliich different foods may be digested is of some significance. For instance, two kinds of food may be equal to each other in respect to the quantities of the different nutrients which they contain and the thoroughness with which they may be digested, but one may be more easily digested than the other and con- sequently in certain circumstances somewhat the more advantageous. Different meats, therefore, or similar kinds of meats cooked in diif erent ways, though in other respects apparently of equal nutritive value, ma}^ differ in actual value because of variation in the ease of digestion. Several investigators have attempted to study the ease or rapidity with which different foods maybe digested, and among the investiga- tions are some with meats cooked in various ways. Two methods have been followed in these investigations, one consisting of direct examination of the stomach contents at different periods after eating and the other comprising experiments with artificial digestive solu- tions. Reference is here made to some of these investigations, but the purpose is to give an idea of the nature of the work that has been undertaken and of the results obtained rather than to include a com- plete summary of what has been accomplished. EXAMINATION OF STOMACH CONTENTS. Among the most famous of such experiments, in which the time of digestion in the stomach of meats prepared in dift'erent ways was studied, are those made by Beaumont ° many years ago. His subject was an otherwise normal man who had been shot throuo;h the stomach and whose wound had so healed as to leave a valvular opening into the stomach through which its contents could be observed and removed. Beaumont reports that meats remained in the stomach for the periods given in Table 25. a The Physiology of Digestion, 2. ed. Burlington, Vt., 1847. 60 Table 25. — Results of observations on gastric digestion. Kind of meat. Turkey ,domestic Do Beef, fresh, lean, rare Beef, fresh, lean, dry Beefsteak Beef with salt only Beef with mustard, etc . . . . Beef Beef, old hard, salted Fork , stea k Pork, fat and lean Pork, recently salted Mean Method of time of cooking. Ch^TTlifi- cation. H. m. Roasted .. 2 30 Boiled.... 2 25 Roasted.. 3 00 do 3 30 3 00 Broiled . . Boiled 2 4.5 do.... 3 00 Fried..... 4 00 Boiled 4 15 Broiled... 3 15 Roasted . . 5 15 Boiled 4 30 Kind of meat. Method of cooking. Fried... Broiled. Raw Pork, recently salted . . . Do Do Do I Stewed. Mutton, fresh Roasted . Do I Broiled. . Do BoUed... Veal, fresh Broiled. . Do Fried.-... Fowls, domestic ! Boiled. . , Do Roasted. Mean time of chj'mifi- cation. H. m. 4 15 3 15 00 00 3 15 3 00 00 00 30 00 00 From experiments with a boj;^ having a gastric fistula, Ufl'ehnan'* drew, in effect, the folhnving conchisions regarding the time of gastric digestion of different kinds of meats: All the observations firmly established the fact that the boy digested raw scraped beef more quickly than finely chopped ham, but not so quickly as roasted beef. The first was undoubtedh^ more quickly penetrated by the gastric juice. However, it fell apart into minute»iibers less easily, and the conclusion may safely be drawn that the digestion of the raw meat took place somewhat more slowly than that of the roasted. Jessen ^ studied the gastric digestion of raw and cooked beef and raw mutton, veal, and pork. His subject was a health}^ man, from whom, by means of a stomach pump, the contents of the stomach were removed at intervals after the food was eaten. He found that 100 iirams of the various kinds of meat left the stomach in the time given below : Hours. Beef, raw, shredded 2 Beef, boiled , rare 2h Beef, boiled, well done 3 Beef, broiled , rare 3 Beef, broiled, well done - 4 Mutton, raw, shredded , 2 Veal, raw, shredded 2i Pork, raw, shredded 3 ^lore recent experiments of similar nature, from which much of the current information regarding the rates of gastric digestion of diflerent foods has been derived, are those by Penzoldt "^ and by Verhaegen.'' It will be observed that experiments of this nature show chiefly the lenoth of time that foods remain in the stomach and the time a Deut. Arch. Klin. Med., 20 (1877), p. 535. i'Ztschr. Biol., 19 (1883), p. 129. ^Deut. Arch. Klin. Med., 51 (1893), p. 535. d Physiologie et Pathologic de la Secretion Gastrique, Paris, 1898. 61 required for reduction of the food to the condition of chyme, in which ' condition it passes to the intestine. But digestion is by no means completed in the stomach. In fact the material from the stomach is acted upon much further by the ferments in the intestine, and these experiments show nothing regarding intestinal digestion. ARTIFICIAL DIGESTION EXPERIMENTS. Artificial digestion experiments — that is, those in which the action of the digestive juices is studied outside of the body — are open to much the same objection as direct observation of the gastric con- tents. In the first place, it is im.possible to reproduce artificially all the conditions of natural digestion, aside from temperature and strength of the digestive fluids, which aid in dissolving the food, and doubtless for this reason artificial digestion is always slower than natural. Beaumont " made such experiments in connection with his natural gastric experiments, and found that to produce the same effect on the food outside of the body as in it required rarely less than twice, and often three and one-half times, as long a period of digestion. Furthermore, artificial-digestion experiments, as most commonly made with pepsin, show nothing of the digestibility of fats, which depends largely on their saponification in the intestines, and, so far as the authors have learned, little work has been done with meats to study the effect of trypsin of the pancreatic juice in breaking down peptones into simpler, more absorbable bodies, so that even as regards the digestibility of protein the results of experi- ments of this nature must be regarded as incomplete. Nevertheless since Stutzer ^ in 1880 proposed the method of making such experi- ments, which, considerably revised and elaborated, is still most com- monly used, much valuable work of this nature has been done. Very little, however, refers especiall}^ to the digestibility of meat prepared in difi"erent ways. Among the earliest artificial digestion experiments with meats w^ere those carried on by Jessen " in connection with liis study of natural digestion. In these experiments 250 grams of beef from a steer about 2 years old were freed as completely as possible from sinew, fat, gristle, and bone, and similar portions of it were boiled until half done, well boiled, roasted underdone, and well roasted. The cooked meats were then partially dried and samples of each, and also of the raw meat, weighing 25 grams were treated with 400 cubic centimeters of an acid pepsin solution containing in some cases 1 gram and in others 2 grams of pepsin per liter of either 0.1 or 0.2 per cent hydro- chloric acid. The digestion was continued for twenty-four hours, with frequent stirring, at a temperature of 37° C. The insoluble a Op. cit., p. 292. bjom. Landw., 28 (1880), pp. 195, 453. cZtschr. Biol., 19 (1883), p. 129. 62 residue was then removed by filtration, dried at 100-110° C. for two to five hours, and weiglied. In these tests the following coefficients of digestibility were obtained: Raw beef 77.32, boiled beef underdone 62.02, well-boiled beef 28.20, roasted beef underdone 60.96, and well- roasted beef 31.72 per cent. From these results it was concluded that raw meat was more easily digested than cooked meat. Chittenden and Cummins " made a few experiments on the relative digestibility of raw and cooked meats in connection with artificial digestion experiments with fish. In each case 20 grams of meat either raw or cooked in a steam bath and freed as completely as pos- sible from sinew, fat, skin, and bone were treated in a beaker with 200 cubic centimeters of a digestive solution containing 5 grams of pepsin in 1,000 cubic centimeters of pure hydrochloric acid of exactly 0.2 per cent strength. The digestion was continued for twenty-two hours at a temperature of 38° to 40° C. with occasional stirring. At the end of this period the solution was cooled to 20° C, diluted to 250 cubic centimeters, thoroughly mixed, and then filtered through a dry filter. Of the clear filtrate 50 cubic centimeters were evapo- rated to dryness in a weighed dish after the addition of 5 cubic centi- meters of a standard solution of sodium carbonate of such strength as to exactly neutralize the acid present. The residue was then dried to constant weight at 110° C. Control experiments were also made with the acid pepsin solution alone, and the residue obtained from the blank experiment was subtracted from the weight of the residue left by the evaporation of the 50 cubic centimeters of the digested mixture. The quantity thus obtained was multiplied by 5. which gave the amount of matter (peptones and intermediate prod- ucts together with some salts) dissolved from 20 grams of meat. From their experiments these investigators found that under the conditions mentioned less of the cooked meat was digested than of the raw meat. Popoff '' conducted experiments on the rapidity of digestion in wliich he used, among flesh foods, beef prepared in different ways. His digestive solution was prepared by adding 8 grams of pepsin and 4 grams of hydrochloric acid to 1 liter of water. The quantity of this mixture used for each sample was diluted by an equal volume of water. The beef, which was comparatively lean, was scraped as free as possible of connective tissues and divided into portions of equal weight to be used for analysis and experiment. In the one series of experiments part of the meat had begun to decompose slightly, but it was nevertheless used in order to test its comparative digestibility. The cooking was done in a steam apparatus without the addition of water in the first two series and with 100 cubic centimeters of water rtAmer. Chem. Jour., 6 (1884-85), p. 318. b Ztschr. Physiol. Chem., 14 (1890), p. 524. 63 in the last two. The artificial digestion was conducted at a tempera- ture of 39° C. and continued five and one-half hours m the first and second series, four hours in the tliird, and three hours in the fourth. At the end of these periods peptonization was arrested by the addition of 80 milligrams of calcium carbonate. The quantity of protem m the undigested portion was determmed and subtracted from that found in a corresponding sample not digested. From his experi- ments Popoff concluded that beef is more readily digested in the raw than m cooked condition; that cooking decreases its digestibility; that the longer it is cooked the more difficult its digestibility becomes. Stutzer" also made some experiments by the method of artificial digestion which he devised to determine whether raw ineat is as rapidly digested as cooked meat. For this purpose he divided a large piece of good lean beef into two parts, one of which he cut into coarse pieces, which he dried at 40° C. and ground fine. The other part he cooked in an ordinary manner, and then cut it up, dried, and ground it in the same way that he did the uncooked part. He treated small portions of each in the same manner with digestive solutions. He used solutions of different strength, but in each case digestion was continued at 38° to 40° C. for thirty minutes. From a comparison of the proportions of the original nitrogenous material that were actually dissolved he drew a conclusion in harmony with that of Popoff's, that the digestibility of the meat was decreased by cooking. The more specific object of some of the above-mentioned investi- gations was to determine the total amount of nitrogenous material that would be digested under certain conditions. Thev do not give much information regarding the ease of digestion. The experiments made by Popoff and Stutzer, however, were made, as explained, to compare the relative ease of digestion of raw and cooked meat; but these give practically no information as to whether differences in methods of cooking the meat have different effects upon the ease of digestion. INVESTIGATIONS HERE REPORTED. Some knowledge regarding the effects of different methods of cook- ing upon the ease or rapidity of digestion of meat seemed especially desirable. The investigations undertaken by the authors regarding the various factors that influence the nutritive value of meat seemed to offer very favorable opportunity for a study of this subject. Accordingly, in connection wdth the experiments on the complete- ness of digestion reported on preceding pages of this bulletin, atten- tion was devoted to a study of the relative ease of digestion of different kinds and cuts of meat, cooked in different ways. "Landw. Vers. Stat., 40 (1892), p. 321. 4663— Rule 193—07 5 64 It was, of course, impossible to make such study by observation of the natural process of digestion with the different subjects, and none of the data actually obtained in the natural digestion experi- ments throw any light upon the ease of digestion of the meats used. It is possible that in time our knowledge of the metabolic products may be such that these will afford some indication of the ease of digestion, but as yet it is entirely inadequate. The only method available, therefore, was that of artificial digestion. The limitations of such experiments in a study of total digestibility have already been pointed out. Similar criticism might also be made of the use of such methods for a study of ease of digestion. It seemed reason- able to believe, however, that the method could be so adapted as to give approximately correct evidence of the rapidity with which pro- tein may be peptonized. Incomplete as such evidence may be, it would seem possible to make it trustworthy so far as it applies, and in the present lack of more definite information it would be of great practical value in dietetics, especially for dyspeptic and other persons who must be relieved to some extent of digestive effort. In all, 99 artificial digestion experiments were completed as de- scribed in detail on the following pages. r Of these 7 were of a pre- liminary nature, made in connection with the study and development of method described below; the other 92 were conducted according to the method finally adopted. DEVELOPMENT OF METHOD. None of the methods followed in the earlier investigations men- tioned was especially adapted, m all particulars, to the purposes of the experiments which it was desired to undertake; nor could the present authors discover any investigations m which the Stutzer method of artificial digestion had been modified in such a way as to show the relative ease or rapidity of digestion of different foods. Atten- tion had to be devoted at first, therefore, to a development of a suitable method of procedure. The various factors that had to be taken into account in order to provide a method by which uniformity of results under identical conditions could be secured are here con- sidered in more or less detail. Composition of the digestit^e solution. — ^A few preliminary tests were made, to determine the most suitable composition of digestive solution. In each case 2.5 grams of pepsin were dissolved in 1 liter of hydrochloric acid; but three strengths of acid were used — one of 0.2 per cent, one of 0.33 per cent, and one of 0.2 per cent at the beginning but with subsequent additions of 10 per cent acid until the strength of the acid in the solution was 0.5 per cent. The most uniform and satisfactory results obtained were those with a digestive solution made by adding 2.5 grams of pepsin to 1 liter of 0.33 per 65 cent hydrochloric acid, and this was adopted as a standard digestive solution for the preliminary investigations. Of this standard solution the same amount, 100 cubic centimeters, was used for each sample. Proportion of meat to a given amount of digestive solution. — The total action of the digestive solution is appreciably affected by the quantity of material to be dissolved. A given amount of the solu- tion will digest a smaller sample more thoroughly than a larger one when the other conditions are the same in both cases. It was not the purpose of these experunents to determine the maximum digesti- bility of meat under given conditions, but it was believed that the ])articular ])urpose of the investigation could be more satisfactorily attained if the size of the sample were such that its retarding influence upon digestion would be minimized. From the results of study of this question it was concluded that from 0.8 to 1.2 grams of dry powdered meat was the most suitable size of sample to be used with 100 cubic centimeters of the standard digestive solution. This proportion is decidedly smaller than that used by some of the other investigators mentioned above, notably Jessen, and Chittenden and Cummins. It was found, however, that the total digestibility obtained with the smaller sample was in the main larger than those obtained by other investigators, and the results with similar samples were much more concordant. Temperature of digestion. — In so many of the previous investiga- tions the temperature of 38° to 40° C. had been found satisfactory that it was adopted in the present experiments without much pre- liminary testinc^. Filtering the digested product. — The effect of the digestive solution upon the meat was determined by comparing the quantity of nitrogen in the material before digestion with that remaining in the undigested residue. Because of the slowness with which the solution filtered, an attempt was made at first to determine the nitrogen in aliquot parts of the filtrate, as w^as done by Chittenden and Cummins and by Stutzer. The unavoidable evaporation of the solution, the use of large factors to fiiid the total amount digested, and the necessary corrections for nitrogen of pepsin, afforded so much opportunity for error that this method was soon discarded. Efforts were then made to provide some method for more rapid filtration. Qualitative filter paper was tried, but though the solution passed through it rapidly the undigested residue was not all retained. The suction pump with hardened filter paper was inconvenient, as it required too much attention and was about as slow as without the use of the pump. The method that proved most satisfactory, and which was finally adopted, is as follows: Hardened quantitative filter paper, 9 centi- meters in diameter, containing 0.1 milligram of nitrogen per paper, was folded in 32 sectors so as to present a corrugated surface and 66 expose practicably all of it to the filtering solution. Such folded filter papers were placed in two funnels, held one above the other, and the flask containing the solution inverted in the top fuiuiel so that the solution would run into the filter automatically. Such an arrangement required very little watching. When the solution had all passed through both papers the residue was washed free from pe])t()nes, and both filt(>r paj:)ers, with their residues, were put into the Kjeldahl flasks for the nitrogen determination. The tops of the filter papers were cut oft", when necessary and practicable. Duration of the digestive period. — Several preliminary experiments were made to determine what length of time the digestion should be continued. Chittenden and Cummins digested their samples for twenty-two hours; but their object was to ascertain total or maximum digestibility. Stutzer, on the other hand, in studying the relative ease of digestion of raw and cooked meat, digested his samples only thirty minutes. The results obtained in the first of the preliminary tests in the present investigation are reported in Table 26. All the samples used in the tests included in the upper portion of Table 26 were from the same cut of beef round from an animal about 5 j^ears old. Portions of this cut were cooked as follows: In water at 80° to 85° C. for two hours and for five hours; pan ])roiled, i. e., fried without added fat; and fried in hot lard. Several samples of the meat cooked by each method, and also of the uncooked meat, were digested in the fresh state (i. e., not dried and ground). In each case the sample was treated with 100 cubic centimeters of digestive solution containing 2.5 grams of pepsin solution in 1 liter of 0.33 per cent hydrochloric acid, and the digestion was continued at 38° to 40° C. for twenty-four hours. In the tests included in the lower part of Table 26 the digestion was conducted in exactly the same way, but the samples, which were all lean beef round, were from different animals. Nos. 1107 and 1108 were parts of the same cut from an animal 6 years old, the former uncooked and the latter cooked in water at 80° to 85° C. tor two hours. No. 1116 was from an animal about 5 years old, and was cooked in water for two hours. Nos. 1119 and 1120 were portions of the same cut from an animal 6 years old, the former uncooked and the latter cooked in water two hours. Nos. 1130 and 1131 were por- tions of the same cut from an animal 4 years old, the former uncooked and the latter cooked in water one hour. No. 1148 was from an animal 2 3'ears old and was cooked in water three hours. In each case the meat was dried and ground fine, and the samples for diges- tion were weighed from the finely ground substance. 67 Table 26. — Tests of effect of acid- pepsin solution upon fresh aiul air-dried samples of raw and cooked beef digested for 24 hours. Description of samples. Nitrogen in- - Propor- tion of total nitrogen indi- gested material. Lab- ora- tory No. Meat. Undi- gested portion. Digested portion. 119.T Tests with fresh samples. Beef round, raw . . ; Gram. 0. 1067 .0949 . .1114 .1310 .1232 .1239 Gram. 0.0026 . f)02S .0032 .0036 .0031 .0032 Gram. 0. 1041 .0921 . 1082 .1274 .1201 .1207 Per cent. 97.56 1195 .do . 97.07 1195 do 97.13 1195 .do 97.25 1195 do 97.48 1195 do 97.42 Average ofStests .1152 .0031 .1121 97.31 Round, cooked 2 hours in water at 80° to 85° C do . . . ..do 1199 1199 li99 .0888 .0852 .1000 .0835 .0909 .0023 .0020 .0026 .0021 .0025 .0865 .0832 .0974 .0814 .0884 97.41 97.65 97. 40 1199 .do 97.49 1199 ....do 97.25 .0897 .0023 .0874 97.44 Round, cooked 5 hours in water at 80° to 85° C .do 1200 1200 .0953 .0843 .0887 .0908 .0981 .0735 .0028 .0028 .0026 .0027 .0030 .0022 .0925 .0815 .0861 .0881 .0951 .0713 97.06 96.68 1200 ...do 97.07 1200 .do 97.03 1200 do 96.94 1200 do 97.01 Average of 6 tests .0885 .0027 .0858 96.95 Round, broiled or "dry fried " 1197 .0688 .0867 .0780 .0790 .0728 .0025 .0030 .0029 .0026 .0027 .0663 .0837 .0751 .0764 .0701 96.37 1197 do 96.54 1197 do 96.28 1197 ...do 96.71 1197 do 96.29 Average of 5 tests .0770 .0027 .0743 96.49 Round, fried in hot lard 1198 .0765 .0631 .0672 .0803 .0783 .0724 .00.37 .00.32 .0033 .0040 .0035 .0036 .0728 .0.599 .0639 .0763 .0748 .0688 95.29 1198 . .do 94.93 1198 do 95.09 1198 .do 95.02 1198 do 95.53 1198 do 95.03 Average of 6 tests .0730 .0036 .0694 95.07 Tests with air-dried samples. 1107 .1450 .1237 .1325 .0031 .0024 .0025 .1419 .1213 .1300 97.86 1107 Round, raw, 2d test 98.06 1107 Round, raw, 3d test . . 98.11 .1337 .0027 . 1310 97.98 Round, boiled 2 liours, 1st test 1108 .1264 .1199 .0025 .0030 . 1239 .1169 98.02 1108 Round, boiled 2 hours, 2d test 97.50 Average of 2 tests .123; .0027 .1204 97.87 Round, boiled 2 hours, 1st test .. .. 1116 .1203 .1254 .1432 .0029 .0029 .0035 .1174 .1225 .1397 97.59 1116 Round, boiled 2 hours, 2d test 97.68 1116 Round, boiled 2 hours, 3d test 97.56 Average of 3 tests .1296 .0031 .1265 97.61 Round, raw, 1st test 1119 .1223 .1294 . 1386 .00.30 .0030 .00.32 .1193 .1264 .1354 97.55 1119 Round, raw, 2d test . . . 97.68 1119 Round, raw, 3d test 97.69 Average of 3 tests .1301 .0031 .1270 97.62 Round, boiled 9. hours, 1st, test 1120 .1275 .1193 .1350 .0030 .0028 .0031 . 1245 .1165 .1319 97.65 1120 Round, Ijoiled 2 hours, 2d test 97.65 1120 Round, boiled 2 hours, 3d test '. 97.70 Average of 3 tests .1273 .0030 .1243 97.64 68 Table 26. — Ttsts of effect of acid-pepsin solution upon fresh and air-dried samples of raw and cooked beef digested for 2Jt hours — rontiniied. Lab- ora- tory No. 1130 1130 1131 1131 1131 1148 1148 1148 Descript ion of samples. Trstx with air-drird .tamptr.s — Continued. Round, raw, 1st test Round, raw, 2d test Average of 2 tests Round, boiled 2 hours, 1st test Round, l)oiled 2 liours, 2(1 test Round, boiled 2 hours, 3d test Average of 3 tests Round, boiled 2 hours, 1st test Round, boiled 2 hours, 2d test Round, boiled 2 hours, 3d test Average of 3 tests Average of 8 series of tests Nitrogen in- Meat. Oram. 0.1517 .2063 .1790 .1796 . 1258 .1178 Undi- gested portion. Gram. 0.0044 .0046 .0045 .0043 .0024 .0022 .1411 .0030 .1211 .1456 .1287 .0033 .0047 .0037 Digested portion. Gram. 0. 1473 .2017 .1745 .1753 .1234 .1156 Propor- tion of total nitrogen in di- gested material. Per cent. 97.10 97.77 97.49 97.61 98.09 98.13 .1381 .1178 .1409 .12;"iO .1318 .1370 .0039 .1279 .0032 .1337 97.87 97.28 96.77 97. 13 97.04 97.59 From the results of these tests it seemed quite evident that the nitrogenous material of the meat was rather completely dissolved when the digestion was continued for twenty-four hours. Further- more, it also appeared that there was no material difference in the thorougliness of digestion whether the meat was uncooked or cooked in water for two or for five hours. This was about equally true whether the fresh or air-dried samples were considered. In the case of the fresh pan broiled and fried meats the digestion was a little less thorough, but the differences were not very large. It seemed appar- ent from these tests that j^ractically notliing could be learned regard- ing ease of digestion if the action of the pepsin solution used were allowed to continue twenty-four hours. It would be impossible to make sufficient (Hfl'erentiations when the differences were small. ChecJdng the action of the digestive solution. — Attention was next devoted to a consideration of the question whether diflerences in the ease of digestion, if there were anv, could be determined bv continu- ing the digestion for shorter periods. In order to accomplish this, some means of checking the action of the digestive solution had to be found, because the filtering process is at best slow, requiring twenty- four to twenty-five liours, and would afford opportunity for consid- erable differences in results if the action of the pepsin were allowed to continue unchecked . The effect of lowering the temperature of the solution was first tested. Chittenden ° suggests that a lowering of the temperature below 38° C. causes an immediate effect upon proteolysis. He states o Digestive Proteolysis, p. 18. 69 that '^ exposure to a low temperature retards proteolytic action doubt- less in the same manner that cold checks or retards other chemical changes." In accordance with tliis idea, experiments were made to determine the action of the pepsin solution at room temi:>erature (22° to 26° C.) and at the temperature of the refrigerator (4° to 5° C.) to learn whether in that way the action of the pepsin could be stopped. The results of these experiments are given in Table 27. The samples used were the same as in the tests given in Table 26, and the other conditions aside from temperature were identical with those of the experiments there reported. The tests were made in duplicate or triplicate in each case. Table 27. — Tests of effects of low temperature upon the action of the acid-pepsin solution. Description of sample. Digested at 22° to 26° C. Digested at 4° to 5° C. Nitrogen in- Pro- por- tion of total nitro- gen in digest- ed ma- terial. Nitrogen in- Pro- Sample No. Total sam- ple. Undi- gested por- tion. Digest- ed por- tion. Total sam- ple. Undi- gested por- tion. Digest- ed por- tion. tion of total nitro- gen in digest- ed ma- terial. 1107a 1107b 1107c Lean beef round, raw do do. . Gram. 0. 1219 . 120o .1203 Oram. 0. 0054 . 005.3 .0047 Gram. 0. 1165 .1153 .1156 Per ct. 95.57 95.61 96.09 Gram. 0. 1155 .1244 .1162 Gram. 0.0108 .0101 .0114 Gram. 0. 1047 .1133 .1048 Per ct. 90.65 91.08 Average ... _ .1209 .0051 .1158 95.76 .1187 . 0108 1 . 1076 90.64 Lean beef round, cooked in water 2 hours... 1116a .1247 . 1282 .0037 .0046 .1210 .1236 97.03 96.41 .1290 .1379 .0098 .0126 .1192 .1253 92.40 1116b do 90.86 Average. . 1264 .0041 .1223 96.72 .1335 .0112 .1223 91.63 Lean beef round, raw do .do... . ... 1119a 1119b 1119c .1182 .1196 .1281 .0055 .0057 . 004.1 .1127 .1139 .1236 95.35 95. 23 96.49 .1292 .1244 .0092 .0085 .1200 . 11.59 92.88 93.17 Average. ,1220 .0052 .1167 95.69 .1268 .0089 .1179 93.02 On comparing these results with the ones given in Table 26, it was plain that with the standard digestive solution acting for twenty-four hours the digestion was nearly as thorough when the temperature was 22° to 26° C. as when it was kept at 38° to 40° C, and even at the temperature of 4° to 5° C. it was only a little less complete. It was evident, therefore, that lowering the temperature of the solution would not stop the action of the pepsin sufficiently for the purpose of these experiments. Attention was then turned to the effect of different substances upon enzyms. Kuhne "■ has pointed out that pepsin is destroyed by digestion with alkaline solutions. Bertels ^ and Dubbs " found that large amounts of chloroform decrease the digestive power of pepsin. oVerhandl. Naturhist. Med. Ver. Heidelberg, Feb., 1876. fcArcli. Path. Anat. u. Physiol. [VirchowJ, 130 (1892), p. 497. clbid., 134 (1893), p. 519. 70 Other investigators have found various other substances to have simi- lar effects. In connection with the present investigation, chloroform, mercuric chlorid, and formalin were tested. Chloroform slightly precipitated the peptones or the intermediate products of the action of pepsin upon proteids. Mercuric chlorid also tended to form a slight precipitate. For this reason the use of these two substances was abandoned. Formalin produced no precipitate, but apparently it did not com- pletely check the action of the pepsin. A series of experiments were made, however, to determine whether it could not be satisfactorily employed for the purposes of these investigations. Samples of raw and cooked meat were treated with 100 cubic centi- meters of pepsin solution containing 10 cubic centimeters of 40 per cent formalin, kept at room temperature for twenty-four hours, then filtered, and the nitrogen determined in the imdigested residue. In connection with these tests the same meats were also dio-ested in the same way with 100 cubic centimeters of 0.33 per cent hydro- chloric acid without pepsin, to determine how much of the solvent action was due to the acid alone. The data of both these tests are given in Table 28. Table 28. — Tests of effect of formalin upon the action of the acid-pepsin solution. Doscription of sample. Digestion with acid-pepsin solution containing formalin. Digestion with acid a lone. Nitrogen in- Pro- portion of total nitro- gen in di- gested mate- rial. Nitrogen in- Pro- portion of total nitro- gen in di- gested mate- rial. Sample No. Total sample. Undi- gested por- tion. Di- gested por- tion. Total sample. Undi- gested por- tion. Di- gested por- tion. Gram. 0. 0300 .0325 1107a 1107b Lean beef round, raw do Gram. 0.1185 .1240 Gram. 0. 0661 .0700 Gram. 0. 0524 .0540 Per ct. 44.22 43.55 Gram. 0. 1302 .1366 Gram. 0. 1002 .1041 Per ct. 23. 04 23. 80 Average .1213 .0681 .0532 43.86 .1334 .1022 .0312 23.42 Loan beef cooked in water do 1116a lllfib . 14.53 .1205 .0962 .0784 .0491 .0421 33. 79 34.94 .1318 .1299 .1198 .1184 .0120 .0115 9.10 8.85 Average .1329 .0873 .0456 34.37 .1308 .1191 .0117 8.98 Lean Ix^ef round, raw do Average . 1119a 1119b .1144 . 1178 .0535 . 0625 .0609 . 0553 53.23 46. 94 .1288 .1152 .1046 .0937 .0242 .0215 18.79 18.66 .1161 .0580 .0581 50.08 .1220 .0992 .0228 18.73 Lean beef round, cooked i n wa tor 1120a .1129 .1245 . 06l7 . 0694 .0512 .0551 45.35 44.26 .1212 .1147 .1062 .1009 .0150 .0138 12. 3S 1120b . ..do... 12.03 Average i 44.81 .1180 .1036 .0144 12.20 Lean boef round, raw do 1130a 1130b .1449 .1450 .0899 .0908 . 0550 . 0542 37.96 37.38 . 1333 .1348 .1177 .1180 .0156 .0168 11.70 12.40 ^Average .1450 .0904 .0546 37.67 . 1340 .1178 .0162 12.08 Loan beef round, cooked in water do A vcrage 1131a 1131b .1202 . 1358 .0719 .0820 .0483 . 0538 40.18 39. 62 . 1245 .1228 .1075 .1052 .0170 .0176 13.65 14.33 .1280 .0769 .0511 39.90 .1236 .1063 .0173 13.99 71 It was evident from these tests that the acid alone had a very- appreciable influence upon the digestion of the meat, but that much more was due to the pepsin, since even in the presence of formalin the complete solution tligested on the average nearly three times the amount of protein that was dissolved by the acid alone. From a comparison of these results with those given in Table 27, which were obtained by digesting with the acid-pepsin solution mthout formalin at room temperature for twenty-four hours, it appeared that the presence of the formalin prevented approximately 55 per cent of the protein from being dissolved. It seemed probable that the more easily digestible material would be dissolved first, and that if the formalin were added after diirestion had continued for some time there would be little, if an}^, further action of the digestive solution during the time required for filtering. To test this h}^othesis two sets of experiments were made. In one set digestion was continued for exactly one hour, then 10 cubic centi- meters of formalin were added and the solution filtered as rapidly as possible. In the second set the digestion was conducted in exactly the same way, the formalin was added at the end of the hour, and the solution was then allowed to stand twenty-three hours before being filtered. The undigested residues were washed, and nitrogen deter- mined in them in the same way. The data of the tests are given in Table 29. Table 29. — Tests of effect of adding formalin after digestion had continued one hour. Description of sample. Digested 1 hour, added forma- lin, filtered at once. Digested 1 hour, added forma- lin, and kept at room tem- perature 23 hours before fil- tering. Sample No. Nitrogen in- Pro- Nitrogen in- Pro- Total sam- ple. Undi- gested por- tion. Di- gested por- tion. tion of total nitro- gen in digest- ed ma- terial. Total sam- ple. Undi- gested por- tion. Di- gested por- tion. por- tion of total nitro- gen in digest- ed ma- terial. 1107a 1107b Lean beef, round, raw do Gram. 0. 1147 .1189 Gram. 0. 0205 .0194 Gram. 0.0942 .0995 Per ct. 82.13 83.68 Gram. 0. 1112 .1084 .1229 Gram. 0. 0243 .0222 .0247 Gram. 0. 0869 .0862 .0982 Per ct. 78.15 79 52 1107c do 79 90 Average .1168 .0199 .0968 82.88 .1142 .0237 0904 1 79 16 1120a 1120b 1120e Lean beef, round, cooked in water do do .1091 .1183 .1258 .0298 .0312 .0331 .0793 .0781 .0927 72.69 73.63 73.69 .1230 .1186 .1156 .0438 . 0.325 .0391 .0792 ' 64 38 .0861 72.60 . 0765 1 66. 18 1130a 11.30b 1130c Average .1177 1 .0313 .0864 73.41 .1191 .0385 0806 1 67 67 Lean beef, round, raw do .1253 .1282 .1502 .0419 .0437 .0674 .0834 .0845 .0828 66.56 65.88 55.13 .1483 .1200 .056.5 .0421 .0918 1 61.90 0779 64. 91 do Average .1346 . 0510 i . 0S.36 62.11 .1342 .0493 . 0849 6.3 5!fi 72 Table 29. — Tests of effect of adding formaUn after digestion had eontintied one lionr- Coiiliiuic'd. Description of sample. Digested 1 hour, added forma- lin, filtered at once. Digested 1 hour, added forma- lin, and kept at room tem- perature 23 hours before fil- tering. Sample No. Nitrogen in- Pro- por- tion of total nitro- gen in digest- ed ma- terial. Nitrogen in— Pro- Total sam- ple. Undi- gested por- tion. Di- gested por- tion. Total sam- ple. Undi- gested por- tion. Di- gested por- tion. por- tion of total nitro- gen in digest- ed ma- terial. 1131a Lean beef, round, cooked in water Oram. 0. 1315 .1292 .1177 Gram. 0. 0392 .0446 .0379 Gram. 0. 0923 .0846 .0798 Per ct. 70.19 65.48 67.79 Gram. 0. 1317 .1162 .1350 Gram. 0. 0472 .0312 .0392 Gram. 0. 0845 .0850 .0958 Per ct. 64. 16 1131b . ...do 73. 15 1131c do Average 70.96 .1261 .0406 .0856 67.88 .1276 .0392 .0884 69.28 Lean beef, round, cooked in water 1148a . 1244 .1207 .1275 .1229 .128G .0300 .0194 . 0330 .0306 .0944 .1013 .0945 . 0923 75.88 83.93 74.12 75.10 7a 95 .1247 .1162 .1170 .1196 .1341 .1188 .0298 .0198 .0218 .0294 .0353 . 0313 .0949 .0964 .0952 .0902 .0988 76. 10 1148b .do 82.96 1148c 1148d do do 81.37 75.42 1148e do . 0335 - 0951 73 68 1148f do . 0875 1 7a 65 Average .1248 .0293 .0955 76.52 . 1217 1 . 0279 .0938 77.07 In some casos the results of these tests were not very satisfactory, but on the whole they seemed to warrant the conclusion that after digestion had continued for "an hour or more, formalin could be used quite effectively to check the action of the pepsin solution, so that there would be little or no further digestion during the filtering process. TESTS OF METHOD ADOPTED. When these facts had been established, a method for studying the relative ease or rapidity of digestion of meat cooked in different ways seemed available, and the following experiments were carried out: A large piece of lean beef round, from an animal about 5 years old, was divided into five similar portions, one of which (No. 1195) was not cooked, one (No. 1199) was cooked in water at 80° to 85° C. for two hours, one (No. 1200) was cooked in the same manner for five hoiu-s, one (No. 1197) was pan broiled, and one (No. 1198) was fried in hot lard. Each portion was then ground as finely as possible in the fresh condition (i. e., without drying) by passing it several tunes through a meat cutter, and the total nitrogen in a sample of each was determined by the Kjeldahl method. Several samples of each portion ..were digested as follows: Each sample (0.8 to 1.2 grams) was placed in a suitable flask, with 100 cubic centimeters of a digestive solution containing 2.5 grams of pepsin in each liter of 0.33 per cent of hydrochloric acid, and the flask was then placed in a water bath and kept at a temperature of 38° to 40° C. for a definite period. During the digestion the solution was 73 frequently stirred, and the lumps of meat were broken down. At th6 end of the digestion period 10 cubic centimeters of a 40 per cent solu- tion of formalm was stirred into the digestive solution, and the latter was then filtered. The undigested residue was washed on the filter paper, and then dropped with the paper into a Kjeldahl flask and the nitrogen in it was determined. From this quantity and that of the nitrogen in the sample before digestion, the proportion digested was estimated. A comparison of these results for the samples cooked in different ways shows which was the more easily digested under the given conditions. Different lengths of digestion period were tried, namely, one, two, six, and twenty-four hours. The results obtained in digesting the samples twenty-four hours are given in Table 26 preceding. Those for the other three periods named are given in Table 30. Table 30. — EJfect of pepsin solvtion acting upon raic and cooked href for different lengths of time. Period of digestion and description of sample. Nitrogen— Propor- tion of total ni- trogen in digested material. Sample No. In total sample. In undi- gested portion. Indi- gested portion. 119oa Digested for 1 hour. Lean beef round, raw Gram. 0.1959 .1013 .1001 .0875 .1171 .1312 Gram. 0.0700 .0397 .0368 .0178 .0426 .0372 Gram. 0.1259 .0613 .0633 .0697 .0745 .0940 Per cent. 64.27 1195b do 60.51 1195c do 63.24 1195d . do . 79.66 1195e do 63.62 1195f do 71.65 Average .1222 .0407 .0815 66.69 Lean beef round, pan broiled 1197a .0806 .0689 .0662 .0646 .0949 .0780 .0171 .0160 .0145 .0121 .0201 .0181 .0635 .0529 .0517 .0.525 .0748 .0599 78.78 1197b 1197c 1197d do do do 76.78 78.10 81.27 1197e do . . . 78.82 1197f do . 76.80 A\'erage . - .0755 .0163 .0592 78,41 Lean beef round, fried in hot lard do do do do do ; 1198a 1198b 1198c 1198d 11986 1198t .0697 .0686 .0712 .0742 .0745 .0727 .0244 .0247 .0193 .02,55 .0243 .0208 .0453 ,0439 .0517 .0487 .0502 .0519 64.99 64.00 72.61 65.C)3 67,. 38 71.39 Average .0718 .0232 .0486 67,69 Lean beef round, cooked in water 2 hours 1199a .li58 .09.56 .0834 .0733 .0778 .0847 .0213 .0165 .0108 .0089 .0104 .0076 .0945 .0791 .0726 .0644 .0674 .0771 81.61 1199b 1199c do do 82.74 87.05 1199d 11998 1199f do do do Average Lean beef round, cooked in water 5 hours do do do do 87.86 86. ()3 91.03 .0884 .0126 .0758 &5.74 1200a 1200b 1200c 1200d 1200G .0660 .0860 .0750 .0924 .08.53 .0780 .0153 .0204 .0190 .0213 .0201 .0193 .0507 .0656 .0560 .0711 .0652 .a587 76.82 76.28 74.67 76,95 76.43 12001 do 75,26 Average .0804 .0192 .0612 76.12 74 Ta RLE 30. — Effect of pepsin solution acting upon raiv and cooked, beef for different lengths of time — Continued. Period of digestion and description of .sample. Nitrogen— Propor- tion of total ni- trogen in digested material. Sample No. In total sample. In undi- gested portion. Indi- gested portion. 1195a Digested for Z hours. Lean becl round, raw . ... Gram. 0.1342 .1022 .0974 .0855 .1161 .1158 Gram. 0.0404 .0175 .0218 .0116 .0254 .0163 Gram. 0.0938 .0847 .0756 .0739 .0907 .0995 Per cent. 69 90 1195b do S9 88 1195c do 77 62 1195d do 80 43 11956 do 78 12 1195f do 85 92 Average .1085 .0222 .0863 79 54 Lean beel round , pan Ijroiled 1197a .0714 .0647 .0682 .0671 .0670 . .0084 .0084 .0081 .0074 .0083 .0630 .0563 .0601 .0597 .0587 88.24 1197b do 87 02 1197c do 88 12 1197d do 88 97 1197e do 87 61 Average .0677 .0081 .0596 88 04 Lean beel round , Iried in hot lard 1198a .0958 .0741 .0680 .0844 .0871 .0757 .0190 .0154 .0173 .0180 .0139 .0112 .0768 .0587 .0507 .0664 .0732 .0645 80.17 1198b do 79 22 1198c do 74 56 1198d do 78.67 11986 do 84 04 11981 do 85 20 .0808 .0158 .0650 80.45 1199a .0872 .0978 .1067 .0941 .0911 .0788 .0065 .0077 .0086 .0062 .0048 .0044 .0805 .0901 .0981 .0879 .0863 .0744 92 32 1199b do 92.13 1199c do 91.94 1199d do 93.41 1199e ....do 94.73 11991 do 94.42 Average - .0926 ^ .0064 .0862 93.09 Lean beef round, cooked in water 5 hours 1200a .0702 .0817 .0749 .0744 .0750 .0898 .0152 .0140 .0134 .0132 .0132 .0162 .0550 .0667 .0515 .0612 .0618 .0736 78.35 1200b do 82.86 1200c 1200d 12006 12001 do do do do Average 82.11 82.26 82.40 81.96 .077? .0142 .0635 81.73 119Sa .1044 .0784 .0586 .1110 .0847 .1050 .0142 .0060 .0059 .0057 .0105 .0090 .0902 .0724 .0527 .1053 .0742 .0968 80.40 1195b 1195c 1195d 11956 11951 do do do do do Average Lean beef round, pan Ijroiled . . 92.35 89.93 94.86 87.60 91.49 .0905 .0086 .0819 90.50 1197a .0689 .0764 .0732 .0861 .0673 .0821 .0047 .0055 .0059 .0062 .0028 .0073 .0042 .0709 .0673 0799 .0645 .0748 93.18 1197b 1197c 1197d 11976 11971 do do do do do 92.80 91.94 92.80 95.84 91.11 .0757 .0054 .0703 92.87 iisaa .0729 .0796 .0792 .0739 .0620 .0731 .0071 .0091 .0062 .0052 .0044 .0070 .0658 .07a'i .0730 .0687 .0576 .0661 90.26 1198b .do 88.. 57 1198c do 92.17 1198d do 92.96 11986 do 92.90 11981 . ..do 90.42 Average .0734 .0065 .0669 91.14 75 Table 30. — Effect of pepsin solution acting upon raw and cooked beef for different/ lengths of time — Continued. Sample No. 1199a 1199b 1199c 1199d 1199e 1199f 1200a 12001) 1200c 1200d 1200e 1200f Period of digestion and description of sample. Digested for 6 ftour.s— Continued. Lean beef round, cooked in water 2 hours. do ....do ....do ....do ....do Average . Lean beef round, cooked in water 5 hours. do .do. .do. .do. .do. Average . Nitrogen- Propor- tion of In total sample. In undi- In di- total ni- gested portion. gested portion. trogen in digested material. Gram. Gram. Gram. Per cent. 0.0825 0.0029 0.0796 96.48 . 1057 .0047 .1012 95.74 .0962 .0037 .0925 96.15 0988 .0038 .0950 96.15 .0891 .0028 .0863 96.86 .0869 .0027 .0842 96.89 .0932 .0034 .0898 96.35 .0660 .0030 .0630 95.45 .07(55 .0029 .0730 96.21 .0662 .0031 .0631 95.32 .0725 .0034 .0691 95.31 .0814 .0045 .0769 94.47 .0738 .0034 .0704 95.39 .0727 .0034 .0693 95.32 The averages of the results obtained in the individual tests, includ- ing those given in Table 26 as well as those in the table above, are summarized in Table 31. Table 31. — Summary of results of artificial digestion experiments with raw and cooked beef. ■ Sample No. 1195 1197 1198 1199 1200 Description of sample. Coefficients of digestiliility of meats treated with pepsin solution for — 1 hour. 2 hours. 6 hours. 24 hours Lean beef, round, raw Lean beef, round, pan broiled Lean beef, round, fried in hot lard Lean beef cooked in water 2 hours Lean beef, round, cooked in water 5 hours 66.69 78.41 67. 69 85.74 76.12 79.54 88.04 80. 45 93.09 81.73 90.50 92.87 9L14 96.35 95.32 97.31 96.49 95.07 97.44 96. 95 No conclusions regarding the relative ease of digestion of the dif- ferent samples are drawn from the above data, because they are too few. The particular information that was derived from these tests was that the method developed seemed admirably adapted for a study of the question. The variations in results obtained in dupli- cate tests were in some instances rather wider than is desirable, but it was believed that with more skill in riianipulation, and with such refinement in technic[ue as would come with practice, more uniform results could be obtained. It will be noticed that the above tests were made with meat in the fresh condition, ground as small as possible with a meat cutter or sausage mill; whereas in previous tests the meat had been dried and very finely ground before digestion. A test was made with the uncooked meat used in the above experiment, to determine whether the same results could be obtained with the fresh as with the dried material. Part of the raw meat was dried and ground as usual, and 76 samples were digested in the same way as the fresh samples were. The averao;es of the results obtained in the individual tests are com- pared in Table 32. Table 32. — Comparison of results ivith/rcsh and dried samples of meal. Sainple Kcscription of sample. Coefficients obtained by digestion for— No. 1 hour. 2 hours. 6 hours. 24 hours. 1195 Lean beef, round, raw, fresh substance 66. 69 65. 57 79.54 75.29 90.50 89.14 97.31 1195 Lean beef, round, raw, dried substance 97. 49 The advantage seemed to be in favor of the digestion of the fresh substance. Accordingly in subsequent experiments this method was followed, in general, in order to avoid the drying. and grinding of the material. DETAILS OF EXPERIMENTS ON THE EASE OF DIGESTION OF PROTEIN. As previously stated, 92 experiments were made with different kinds and cuts of meat cooked in diflPerent ways. Of these, 67 were with beef, 5 with mutton, and 20 with ^)ork. In some cases the meats used in these experiments were the same as those in the natu- ral digestion experiments, and in other cases different kinds of meats were used for the artificial digestion tests. The method employed was that explained on preceding pages, except that the strength of the acid-pepsin solution was altered. In all the experiments hereafter reported the digestive solution con- tained 1.25 grams of pepsin, instead of 2.5 grams, in each liter of 0.33 per cent hydrochloric acid. In all other respects the method was as outlined above (p. 72). In several cases a large piece of some particular ^'cut" of meat was divided into several similar portions, one of which was not cooked and the others were cooked in different ways. In such cases there is opportunity for comparing results with raw and cooked meats that before cooking were as nearly alike as possible. In other instances similar cuts of meat from difl'erent animals were used, some of wliich were not cooked , wliile the remainder were all cooked in the same way. Several of the experiments were made with different "cuts" of meat from the same animal, all cooked in the same way, to deter- mine whether there is an}^ difference in the ease of digestion of meat from different parts of the same carcass. Both fat meats and lean meats were used, to ascertain how they compare in respect to ease of digestion. In order that the relative fatness of the meats might be definitely known samples were analyzed in the usual way. The data regarding the composition of these samples are given in Table 33. n't I I Table 33. — Composition of vieats used in artificial digestion experiments here reported. Lab- ora- tory No. Kind of meat. Used in e.xperi- ment No.— Water. Protein (NX6.25). Fat. Ash. 1390 Beef round, cooked in water 43 48 55 70 94 95 41 46 42 47 44 49 45 50 51 6fi 81 82 83 84 85 94 95 96 81 82 83 84 85 91 91 92 92 93 93 94 95 96 97 97 97 52 67 53 68 54 69 56 57 58 59 60 71 72 73 74 75 76 77 78 79 80 86 87 88 63 71 72 73 74 75 76 77 78 79 80 86 87 88 89 Per cent. 61.71 59.52 .53. 12 53. 66 61.79 62.78 76.84 75.64 68.86 59.02 60.54 48. 67 57.92 55.87 51.16 49.43 49.89 48.16 35. 77 46.09 48.54 51.46 46.43 60.00 47.51 40.49 32.94 62.89 56.20 35. 12 49. 63 28.02 42.45 54.53 49.88 45.74 33.30 54.83 43.61 55.11 44.43 60.14 65.00 62.96 58.19 51.80 51.29 42.82 40.82 61.09 38.27 47.77 61.61 54.48 ■ 49. 58 52.54 51.07 54.80 52.73 35.04 55. 88 63.77 58.45 57. 76 58.29 50.49 53.37 50. 45 51.46 48.17 41.20 51.61 51.22 49.38 55.13 54.36 53. 62 56.05 59.12 53.57 Per cent. 36. 20 34. 20 30.08 30.83 33.84 33.75 20.75 21.17 28.18 34.27 32. 54 41.09 35.66 36.34 22.78 18.07 16.11 14. 35 10. 56 13.61 14.82 14.81 12. 60 17.82 20.16 19.73 15. 78 17.89 18. 95 19.50 21.95 21.94 20.97 23.55 20.56 18.22 16.34 19. 26 23.63 24. 64 20.04 26.30 24.88 22.23 18. 15 20.59 19.16 19.70 16.85 22. 15 16.17 18.28 15.76 13. 64 13.90 14.13 14. .50 14.00 13.96 14.76 14.95 16.35 16.10 15.50 17.41 17.32 23.00 16.76 21.78 21.42 29.15 18.99 18.95 23.63 23.44 23. 52 24.77 26.52 23.47 26.40 Per cent. 1.99 6.19 16.34 16.05 3.27 2.65 1.78 2.42 •2.15 6.42 5.95 9.77 6.05 7.60 26.20 32.53 33.77 36.96 53.29 39.58 35.90 33. 62 40.62 21.78 32.08 39.60 .51.32 18.34 24.33 44.92 28.26 49. 60 . 36.85 21.61 28.06 35.49 50.04 25. 16 30.67 18.21 34.09 13.60 10.07 14.58 23.59 27.62 29.67 37.05 42.44 16.60 45. 42 33.69 21.85 31.61 35. 94 33.10 33.82 30.58 33. 07 49.49 29. 05 19.48 24.84 26.50 24.01 31.69 23. ,38 31.92 26.51 29.80 29.63 28.78 29.39 26. 36 2). 20 21.82 21.04 17.09 17.36 19.73 Per cent. 0.93 1395 .do 1.03 1403 do .81 146.5 do .93 1634 .do 1.04 1635 do . 1.01 1388 Beef round, raw 1.09 1393 .do 1.16 1389 Beef round, pan broiled 1.32 1394 do . . 1..50 1391 Beef round, fried in lard 1.40 1396 do 1.62 1392 Beef round, roasted 1..37 1397 .do 1..33 1399 Beef ribs, cooked in water .82 1461 .do .67 1520 Beef rilis, raw .72 1521 do .69 1522 .do .52 1535 .do .67 1541 do .73 1611 .do .72 1612 .do .61 1613 do .86 1537 Beef ribs, roasted .91 1536 ..do .91 1538 do .72 1539 do .80 1540 .do .89 1587 ..do .79 1588 .do .95 1589 .do .87 1590 ....do .82 1591 .do .95 1595 .do 2.37 1615 ..do .92 1614 ....do .74 1616 .do .97 1617 .do 2.34 1561 ..do 2.55 1525 .do 1.93 1400 Beef leg, cooked in water .74 1462 do .89 1401 Beef neck, cooked in water .91 1463 .do .70 1402 Beef flank, cooked in water .71 1464 .do .63 1424 .77 1425 Mutton, flank, cooked in water .56 1426 Mutton, leg, cooked in water .99 1427 Mutton, loin .55 1428 Mutton, ril IS . . ; .67 1482 Pork, fresh ham, raw .83 1485 ....do .66 1487 do .72 1488 . ..do .74 1490 ...do .73 1492 do .70 1505 ..do .78 1507 ....do .82 1510 do .80 1515 . ..do...' .93 1542 do .85 1543 do .77 1544 ..do .82 1432 Pork, fresh ham, cooked in water .66 1483 Pork, fresh ham, roasted 1.02 1484 do .79 I486 do .88 1489 ....do .91 1491 do .99 1493 do .87 1.504 do .96 1506 do.... 1.08 1511 do 1.09 1514 do .88 1545 do 1.00 1558 1559 1573 do do do 1.08 1.02 1.01 78 Table 33. — Composition of vieals used in artijicial digestion experiments here reported- Continued. Lab- ora- tory No. 1574 1575 1580 1430 1431 1433 1434 Kind of meat. Pork, fresh ham, roasted do do Pork, beUy, cooked in water Pork, middle cut, cooked in water Pork, shoulder, cooked in water. Pork, back, cooked in water Used experi- ment No.— n 89 90 90 61 02 64 65 Water. Per cent. 55.43 51.40 61.71 41.32 44.61 60.68 52.96 Protein (NX6.25). Per cent. 24.52 25.88 19.33 15.52 17.22 21.59 21.14 Fat. Percent. 19.44 22. 46 18.27 42.95 37.82 17.31 25.47 Ash. Per cent. 1.05 .99 .74 ..52 .53 .81 .82 EXPERIMENTS WITH BEEF. A description of the kinds and cuts of beef and the methods of cooking is here given. Experiments Nos. 7 to 11 were made with a piece of beef round, from an animal about 2^ years old, which was divided into five similar portions. No. 1202 was not cooked, No. 1203 was pan broiled, No. 1204 was fried in hot lard, No. 1205 was cooked in water at 80° to 85° for two hours, and No. 1200 was cooked in the same manner for five hours. Experiments Nos. 12 to 16 were made with a piese of beef round, from an animal about 3 years old, which was divided into five similar portions. No. 1210 was not cool^ed, No. 1215 was pan broiled. No. 1219 was fried in lard, No. 1211 was cooked in water at 80° to 85° for two hours, and No. 1210 was cooked in the same manner for five liours. Experiments Nos. 17 to 21 were made with a piece of beef round, from an animal about 3 years old, which was divided into five similar portions. No. 1235 was not cooked, No. 1238 was pan broiled, No. 1241 was fried in hot lard, No. 1242 was cooked in water at 80° to 85° for one hour, and No. 1243 was similarly cooked for five hours. Experiment No. 22 was made with a piece of very fat beef sirloin, No. 1279, from an animal about 2| years old. The meat was broiled in a gas oven until somewhat underdone. Experiment No. 23 was made with a piece of very fat beef sirloin, No. 1280, from an animal about If years old. The meat was broiled in a gas oven until well done. Experiment No. 24 was made with a piece of very fat beef sirloin. No. 1281, from an animal about 2j years old. It was broiled in a gas oven until somewhat underdone. Experiment No. 25 was made with a piece of very fat beef sirloin, No. 1282, from an animal about 24 years old. The meat was broiled in a gas oven until somewhat underdone. Experiment No. 26 was made with a i)iece of veiy fat beef sirloin. No. 1283, from an animal about 2^ years old. The meat was broiled in a gas oven until somewhat underdone. Experiments Nos. 27 and 28 were made with a piece of very fat beef shoulder from an animal about 2i years old. The meat was obtained fifteen days after the animal was slaughtered. The piece was cut into two portions, one of which (No. 1300) was not cooked and the other (No. 1287) was cooked in water at 80° to 85° for two hours. Experiment No. 29 was made with a piece of very fat beef sirloin. No. 1302, from an animal about 2 years old. The meat was obtained eighteen days after slaughtering and was not cooked. Experiment No. 30 was made with a i)ii'ce of very fat beef sirloin, No. 1303, from an animal about 3 years old. The meat was obtained eighteen days after slaughtering and was not cooked. 79 Experiment No. 31 was made with a piece of very fat beef sirloin, No. 1305, from' an animal about 2 years old. The meat was obtained eighteen days after slaughtering and was not cooked. Experiment No. 32 was made with a piece of very fat beef sirloin, No. 1306, from an animal about 3 years old. The meat was obtained eighteen days after slaughtering and was broiled in a gas oven. Experiment No. 33 was made with a piece of very fat beef sirloin, No. 1307, from an animal about 3 years old. The meat was obtained eighteen days after slaughtering and was broiled in a gas oven. Experiment No. 34 was made with a piece of very fat beef sirloin. No. 1309, from an animal about 2 years old. The meat was obtained twenty-one days after slaugh- tering and was broiled in a gas oven. The samples were digested nine days after the meat was cooked. Experiments Nos. 35 and 36 were made with a piece of lean beef round from an animal about 3 years old. One portion of the cut. No. 1314, was not cooked; the other portion, No. 1313, was pan broiled until well done. Experiments Nos. 37 and 38 were made with a piece of lean beef round from an animal about 3 years old. One portion of the cut. No. 1331, was not cooked; the other portion, No. 1330, was fried in hot lard. Experiments Nos. 39 and 40 were made with a piece of lean beef round from an animal about 2 years old. One portion of the cut. No. 1348, was not cooked; the other portion, No. 1347, was roasted in a gas oven until well done. Eperiments Nos. 41 to 45 were made with a piece of lean beef round, from an animal about 2^ years old, which was divided into five portions. No. 1388 was not cooked, No. 1389 was pan broiled until well done, and No. 1390 was kept in lioiling water for ten minutes and the temperature of the water was then reduced to 85° and cooking was continued for two hours at 80° to 85°. The meat was well done. No. 1391 was fried in hot lard until well done. No. 1392 was roasted in a gas oven. Experiments Nos. 46 to 50 were made with a piece of lean beef round, from an animal about 3 years old, which was divided into five portions. No. 1393 was not cooked, No. 1394 was pan broiled until well done. No. 1395 was kept in boiling water for ten minutes then cooked for two hours in water at 80° to 85°, No. 1396 was fried in hot lard until well done, and No. 1397 was roasted in a gas oven. Experiments Nos. 51 to 55 were made with different cuts of beef from the same animal, which was about 3 years old at the time of slaughtering. No. 1399 was a very fat first cut of ribs, known locally as "rib roast;" No. 1400 was a moderately fat leg piece, known locally as "soup bone;" No. 1401 was a second cut of the neck, moderately fat, known as a "boiling piece:" No. 1402 was a very fat piece of the flank bone, known locally as the "flank boiling piece;" No. 1403 was a rather fat piece of ])eef round. In each case the meat was cooked by placing it in boiling water, the temperature of which was maintained at 100° for ten minutes, then j-educed to 85° and kept at 80° to 85° for two hours. Experiments Nos. 66 to 70 were made with different cuts of beef from the same animal, which was about 2 years old at the time of slaughtering. No. 1461 was a first cut of the ribs. No. 1462 was a leg piece. No. 1463 was a second cut of the neck, No. 1464 was a flank piece, and No. 1465 was a piece of the round. Each cut was cooked in water which was kept l)oiling for ten minutes and then at 80° to 85° for two hours. Experiment No. 81 was made with beef ribs. One portion (1520) was uncooked and the other jiortion (1537) was roasted. Experiment No. 82 was made with beef ribs. One portion (1521) was uncooked and the other portion (1536) was roasted. Exi^eriment No. 83 was made with beef ribs. One portion (1522) was not cooked and the other pf)rtion (1538) was roasted. 4663— Bull. 193—07 6 80 Experiment No. 84 was made with beef ribs. One portion (1535) was uncooked and the other portion (1539) was roasted. Experiment No. 85 was made with beef ribs. One portion (1541) was uncooked and the other (1540) was roasted. Experiment No. 91 was made with two pieces (1587 and 1588) of roasted beef ribs, very fat. Experiment No. 92 was made with two pieces (1589 and 1590) of roasted beef ribs, very fat. Experiment No. 98 was made with two pieces (1591 and 1595) of roasted beef ribs, very fat. Experiment No. 94 was made with a cut of beef ribs, one portion of which (Kill) was uncooked and the other portion (1615) was roasted. Experiment No. 95 was made with a cut of beef ribs, one portion of which (1612) was uncooked and the other portion (1614) was roasted. Experiment No. 96 was made with a cut of beef ribs, one portion of which (1613) was uncooked and the other portion (1616) was roasted. Experiment No. 97 was made with three cuts (1617, 1561, and 1525) of beef ribs roasted. Experiment No. 98 was made with two similar portions of the same piece of beef round cooked in water that was kept boiling for ten minutes and then at 80° to 85° C. for two hours. One portion (1634) was ground twice in a sausage mill and the other portion (1635) was cut into quarter-inch cubes. The purpose of this experiment was to afford some indication regarding effect of thorongh mastication upon the ease of digestion. The data regarding the artificial digestion of the protein of the above samples are given in Table 35. In a very few cases the figures there given represent the data from individual tests, but in the large majority of cases they are the averages for several tests with the same sample, the number included in the average ranging from 2 to 5, as shown in one of the columns. For example, in the case of the first item in the table, with sample No. 1202 digested for one hour, four tests, a, h, c, and d, were made, the data of which are given in Table 34. Table 34. — Results of individual tests on digestion of raw beef round. Nitrogen in- Proportion of total nitrogen in digested material. Sample No. Total sample. Undigested portion. Digested portion. 1202a Gram. 0.0715 .0730 .1081 . 0728 Gram. 0. 0045 .0045 .0103 .0058 Gram. 0. 0670 .0685 .0978 .0670 Per cent. 94 12026 94 1202f 90 1202(f 92 Average .0814 .0063 .0751 92 The average of the quantities of nitrogen in the four portions of the sample that were weighed for digestion was 0.0814 gram; that in the undigested residue, 0.0063 gram, and in the digested portion, 0.0751 gram. According to these figures 92 per cent, on the average, of the nitrogen of the meat was present in the protein that was digested. Among the individual tests the proportion ranged from 90 to 94 per 81 cent. These latter figures are given in the last two columns of Table 35 to show the variations in results of the individual tests from which the average figures were derived. Table 35. — Results obtained in artificial digestion of samples of different cuts of beef, raw and cooked in different ways. Description of sample. Digested 1 hour. Experiments Nos. 7-11: Beef round — Raw Pan broiled , Fried in hot lard Cooked in water 2 hours Cooked in water 5 hours Experiments Nos. 12-16: Beef round, lean — Raw , Cooked in water 2 hours Cooked in water 5 hours Pan broiled Fried in hot lard Experiments Nos. 17-21: Beef round, lean — Raw Pan broiled Fried in hot lard Cooked in water 1 hour Cooked in water 5 hours Experiments Nos. 22-26: Beef sirloin, very fat, broiled, un- derdone Beef sirloin, very fat, broiled, well done Beef sirloin, very fat, broiled, un- derdone ....do do Average of 5. Experiments Nos. 27-28: Beef shoulder, very fat, cooked in water 2 hours Beef shoulder, moderately fat, raw Experiments Nos. 29-31: Beef sirloin, very fat, raw Do Do Average of 3. Experiments Nos. 32-34: Beef sirloin, very fat, broiled. Do Do Average of 3. Experiments Nos. .35-36: Beef round, lean, raw Beef round, lean, pan broiled, well done Experiments Nos. 37-38: Beef round, lean, raw Beef round, lean, fried in hot lard, well done Experiments Nos. 39-40: Beef round, lean, raw Beef round, lean, roasted, well done Num- ber of tests in av- erage. Nitrogen in- Meat. Gram. 0. 0814 .0720 .0757 .0617 .0767 .0911 .0994 .0943 .0644 .0947 .0950 .0546 .0993 . 0933 .0748 .0490 .0591 .0412 .0498 .0980 Undi- gested por- tion. .0594 .0890 .0970 . 0757 .0476 .0612 .0615 .0663 .0918 .0877 .0819 .1079 .0827 .0873 .1030 .0951 .1109 Gram. 0.0063 .0178 .0205 .0305 .0292 .0127 .0155 .0112 .0144 .0237 .0100 .0090 .0218 .0145 .0136 .0078 .0139 .0109 .0092 .0225 Digest- ed por- tion. .0129 Gram. 0. 0751 .0542 .0552 .0312 .0475 .0784 .0839 .0831 .0500 .0710 .0850 .0456 .0775 .0788 .0612 .0412 .0452 .0303 .0406 .0755 Proportion of total ni- trogen in digested portion. Aver- age. .0466 .0187 .0158 .0159 .0095 .0108 .0121 .0135 . 0186 .0146 .0156 .0125 . 0163 .0142 .0221 .0149 . 01.33 .0703 .0812 .0598 . 0.381 .0504 .0494 .0528 .0732 .0731 0664 .0954 .0664 .0731 .0809 .0802 .0976 Per ct. 92.26 75.28 72.92 50; 57 61.93 86.06 84.41 88.12 77.64 74.97 89.47 83.52 78.05 84.46 81.82 84.08 76.48 73. 54 81.53 77.04 Mini- mum. 78.53 Per ct. 90.44 74.72 72.57 48.13 58.65 85.57 78. 76 85.47 75.93 72.28 87.52 80.48 75.75 81.85 79.28 82.93 68.09 72.28 81.18 76. 19 78.99 83.71 79.00 80.04 82.35 80.46 79.64 79.74 83.35 80.91 88.42 80.29 83.73 78. 54 84.33 88.01 78.37 82. 30 77.58 78.72 82.16 78.22 78.24 82.38 87.10 78.73 S3. 10 77.32 82.10 87. 53 Maxi- mum. Per ct. 93.88 76.05 73.31 53.46 67.52 86.40 89.56 93.86 79.03 76.39 91.38 86.73 80.72 88.15 84.96 84.99 85.83 74.69 81.99 78.63 79.37 85.04 80.00 80.98 82.75 81.54 80.97 84.30 89.40 81.72 84.21 79.47 86.03 88.52 82 Table 35. — Results obtained in artificial dic/estion of samples of different cuts of beef, raw and cooked in different ways — Continued. Labo- ra- tory No. Description of sample. 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1399 1400 1401 1402 1403 1461 1462 1463 1464 1465 1202 1203 1204 1205 1206 1210 1211 1212 1215 1219 1235 1238 1241 1242 1243 1279 1280 1281 1282 1283 1287 1300 Digested 1 Ao«r— Continued. Experiments Nos. 41-45: Beef round, lean- Raw Pan broiled Cooked in water 2 hours, well done Fried in hot lard, well done Roasted, well done Experiments Nos. 46-50: Beef round, lean- Raw Pan liroiled Cooked in water 2 hours Fried in hot lard Roasted Experiments Nos. 51-55: Beef, different outs, all cooked in water 2 hours — First cut ribs, very fat Leg bone, moderately fat Second cut neck, moderately fat Flank, very fat Roimd, rather fat Experiments Nos. 66-70: Beef, difTerent cuts, all cooked in water 2 hours — First cut ribs, underdone Leg bone Second cut, neck Flank, well done Round, well done Num- ber of tests in av- erage. Nitrogen in- Meat. Digested 2 hours. Experiments Nos. 7-11: Beef round — Raw Pan broiled Fried in hot lard Cooked in water 2 hours. . Cooked in waters hours.. Experiments Nos. 12-16: Beef round, lean- Raw Cooked in water 2 hours. Cooked in water 5 hours. Pan broiled Fried in hot lard Experiments Nos. 17-21: Beef round, lean — Raw Pan broiled Fried in hot lard Cooked in water 1 hour.. Cooked in water 5 hours. Experiments Nos. 22-26: Beef sirloin, very fat, broiled, underdone Beef sirloin, very fat, broiled, well done Beef sirloin, very fat, broiled, underdone Do Do Average of 5 . Experiments Nos. 27-28: Beof shoulder, very fat, cooked in water 2 hf)urs Beef shoulder, moderately fat, raw Undi- gested por- tion. Gram. 0.0913 .0897 r .0930 .0738 .0932 .0872 .0827 .0896 . 1031 .0962 .0722 .0750 .0684 .0670 .0942 .0608 .0730 .0680 .0560 .1035 .0887 .0770 .0725 . 0699 .0660 .0848 . 1083 .0851 .0626 .0982 .0970 .0588 .0803 .1069 .0988 Digest- ed por- tion. Gram. Gram. 0. 0098 0. 0815 .0134 .0763 . 0517 .0630 . 0604 .0488 .1123 .0672 .0802 .1015 .0179 .0178 .0161 .0148 .0187 .0249 .0240 .0138 . 0161 .0246 .0172 .0222 .0186 . 01.32 .0157 .0201 .0180 .0178 .0052 .0135 .0097 .0186 .0167 .0076 .0084 .0077 .0079 .0177 .0083 . 0056 . 0076 .008,5 .0098 .0072 . 0095 .0118 . 0061 .0198 .0109 .0123 .0141 .0751 .0560 '. 0771 .0724 .0640 .0647 .0791 .0824 . 0561 .0504 .0512 .0448 . 0757 . 0476 .0573 .0479 . 0380 .0857 .0835 .0035 . 0628 .0513 .0493 .0772 .0999 .0774 . 0547 .0805 .0887 .0532 .0727 .0984 .0890 Proportion of total ni- trogen in digested portion. . 0445 . 05,35 . 0486 .0427 .0925 Aver- age. .0564 . 0679 .0874 Mini- mum. Per ct. 89.27 85. 06 80.75 75. 88 82.73 83.03 77.39 72.21 76.72 85.65 77. 70 67.20 74.8,5 66.87 80.36 78.29 78.49 70.44 67. 86 82.80 94.14 82.47 86. 62 73.39 74.70 91.04 92.24 90. 95 87.38 81.98 91.44 90.48 90.54 92.05 90.08 Per ct. 88.17 83.52 78.44 75. 06 81.90 81.78 76.36 71.12 76.17 84.91 77.27 66.58 73.59 64.53 78.78 86.07 84.92 80. 46 87.50 82.37 Maxi- mum. 78.28 66.53 82.25 93. 83 81.27 85.93 70.20 73. 43 90.83 91.89 88.47 86. 10 78.14 91.11 8.5. 94 89.21 89.00 85.77 Per ct. W. 31 86.60 81.89 77. 05 84.90 84.72 78.34 7.3. 76 77. 35 86.17 78.61 67.64 75. 84 68.74 81.07 85.81 83.19 79.70 86.24 80.31 84.26 84.66 86.11 83.18 &5.21 78.55 69.34 83.68 94.50 85. OS 87.27 75.54 75. 69 91.29 92.93 93. 54 88.95 84.03 91.91 92.98 92. 06 95.70 93.10 86. 31 86. 57 81. 95 - 88. 02 84. 40 8.5.73 87.73 83 Table 35. — Results obtained in artificial digestion of saynples of different cuts of beef, raw and cooked in different ivays — Continued. Labo- ra- tory No. Description of sample. 1302 1303 1305 1306 1.307 1309 1314 1313 1331 1.330 1348 1.347 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1399 1400 1401 1402 1403 1462 1463 1464 1465 1520 1537 1521 1536 1522 1538 1535 1539 1541 1540 Digested 2 Aowrs— Continued. Experiments Nos. 29-31 : Beef sirloin, very fat, Do Do Average of 3. Experiments Nos. 32-34: Beef sirloin, very fat, broiled. Do ". Do Average of 3 . Experiments Nos. 35-36: Beef round, lean, raw Beef round, lean, pan broiled, well done Experiments Nos. 37-38: Beef round, lean, raw , Beef round, lean, fried in hot lard, well done Experiments Nos. 39-40: Beef round, lean, raw Beef round, lean, roasted, well done Experiments Nos. 41-45: Beef round, lean — Raw Pan broiled Cooked in water 2 hours, well done , Fried in hot lard, well done. . , Roasted, well done Experiments Nos. 46-50: Beef round, lean — Raw .■ Pan broiled , Cooked in water 2 hours Fried in hot lard Roasted , Experiments Nos. 51-55: Beef, different cuts, all cooked in water 2 hours — First cut ribs, very fat , Leg bone, moderately fat Second cut, neck, moderately fat Flank, very fat Round, rather fat Experiments Nos. 66-70: Beef, different cuts, all cooked in water 2 hours — Leg bone Second cut, neck Flank, well done Round, well done Experiment No. 81: Beef ribs, very fat, raw Beef ribs, very fat, roasted Experiment No. 82: Beef ribs, very fat, raw Beef ribs, very fat, roasted Experiment No. 83: Beef ril)s, very fat, raw Beef ribs, verj' fat, roasted , Experiment No. 84: Beef ribs, very fat, raw Beef ribs, very fat, roasted Experiment No. 85: Beef ribs, very fat, raw Beef ribs, very fat . roasted Num- ber of tests in av- erage. Nitrogen in — Meat. Gram. 2 0. 0706 3 ' .0517 3 I .0645 .0623 4 . 0768 3 .0806 3 .0936 .0837 .0991 .0919 .1060 .1094 .0888 .0940 .0761 .0895 .0925 .0890 .0863 .1049 .0771 . 1038 .1124 .0949 .0758 .0790 .0686 .0774 .0812 .0763 .0517 .0617 .1046 .0533 .0629 .0519 .0618 .0352 .0532 .0493 .0605 .0470 .0640 Undi- gested por- tion. Gram. 0.0085 .0067 .0078 Digest- ed por- tion. Gram. 0. 0621 .0450 .0567 .0077 .0546 . 0098 . 0670 .0111 .0695 . 0127 . 0809 .0112 .0081 .0119 .0126 .0199 .0093 . 0097. .0085 .0074 .0126 .0110 .0087 .0165 .0123 .0164 .0237 .0078 .0101 .0176 .0140 .0207 .0087 .0112 .0133 .0158 .0130 .0049 .0083 .0072 .0092 .0045 .0084 .0047 .0108 .0075 .0107 .0725 .0910 .0850 .0934 .0895 .0795 .0843 .0676 .0821 .0799 .0780 .0776 .0884 .0648 .0874 .0887 .0871 .0657 .0614 .0546 .0567 .0725 .0651 .0384 .0459 .0916 .0484 .0646 .0447 .0526 .0307 .0448 .0446 .0497 .0395 .0533 Proportion of total ni- trogen in digested • portion. Aver- age. Per ct. 87.96 87.04 87.91 87.64 87.24 86. 23 86.43 Mini- mum. Per ct. 87.70 86.06 86.59 86. 59 86.12 85.99 Maxi- mum. Per ct. 88.21 88.28 89.13 86.63 91.83 87.72 88.11 81.81 89. .53 89.68 88.83 91.73 86.38 87.64 89.92 84.27 84.05 84.20 78.91 91.78 86.68 77.72 79.59 73.26 89.29 85.32 74.28 74.39 87.57 90.81 86.80 86. 13 85.11 87.22 84.21 90.47 82.15 84.04 83.28 9L67 86.81 87.62 80.30 88.54 89.08 88.22 9L16 84.17 86.24 89.09 83.85 83.69 84.03 91.67 85.57 75.33 78.51 72.71 88.57 85.18 69.41 70.52 86.84 87.10 85.61 82.53 84.82 84.55 83.15 89.44 79.97 83.19 82.37 88.26 86. 50 87.16 91.89 88.86 88.77 82.74 90.05 90.60 89.90 92. 79 88.48 88.87 90.42 84.67 84.74 84.25 91.81 87.40 80.18 80.71 73.71 90.01 85.45 77.72 78.37 88.58 93.71 87.95 90.22 85.51 89.49 85.46 91.53 84.45 84.46 84.53 84 Table 35. — Results obtained in artificial digestion of samples of different cuts of beef, rail' and cooked in different uays — Continued. Labo- 1 • Description of sample. Num- ber of tests ; inav-' erage. Nitrogen ir — Proportion of total ni- trogen in digested portion. ra- tory No. Meat. i Undi- 1 gested por- tion. Digest-' ed por- tion. Aver- age. Mini- mum. Maxi- mum. 1587 1588 ; Digested 2 ftours— Continued. Experiment No. 91: Beef ribs, very fat, roasted Do Average of 2 '. . Experiment No. 92: Beef ribs, verv fat, roasted Do ". 4 2 Gram. 0.0638 .0614 Gram, j 0.0099 .0125 Gram. 0.0539 .0489 Per ct. 84.48 79.64 Per ct. 83.51 79.41 Per ct. 84.95 79.93 .0626 j .0112 .0514 82.06 1589 1590 2 3 1 . 0736 1 .0536 ; .0150 .0095 -.0586 .0441 79.62 82.27 79.52 81.53 79.77 83.37 Average of 2 Experiment No. 93: Beef ribs, very fat, roasted Do Average of 2 Average of 6 Experiment No. 94: Beef ribs verv fat. raw. .0636 .0123 .0513 80.95 1591 1595 2 4 .0731 .0553 .0195 .0092 .0536 .0461 73.32 83.36 73.09 81.22 73.64 85.09 .0642 i .0144 .0498 78.34 .0635 .0126 .0509 80.45 1611 4 4 3 3 2 4 .0654 .0613 .0599 .0527 .0781 .0588 *■ .0118 .0141 .0084 .0099 .0126 .0083 .0536 .0472 .0515 .0428 .0655 .0505 81.96 77.00 85.98 81.21 83.87 85.88 79.60 76.21 85.00 80.08 81.95 82.54 85.92 1615 1612 Beef ribs, very fat, roasted Experiment No. 95: Beef ribs, verv fat, raw 77.87 87.66 1614 1613 Beef ribs, very fat, roasted Experiment No. 96: Beef ribs, verv fat, raw. 82.39 85.43 1616 Beef ribs, very fat, roasted Experiment No. 97: Beef ribs, very fat, roasted Do 88.00 1525 1561 3 3 3 .0689 .0809 .0625 .0120 .0174 .0073 .0569 .0635 .0552 82.58 78.49 88.32 81.86 78.40 88.07 82.86 78.72 1617 Do Average of 3 Experiment No. 94: Beef round, cooked in water 2 hours, ground twice in a sausage mill 88.58 . 0708 .0122 .0585 83.13 1634 4 3 4 3 4 5 4 4 4. 4 4 4 3 3 4 4 3 2 .1431 .1100 .0923 .0612 .0595 .0653 .0763 .0916 .0830 .1118 .0689 .0907 .0922 .0495 .0902 .0931 .0936 i .0392 . 0257 .0831 .0053 .0055 .0047 .0095 .0101 .0056 .0046 .0055 .0047 .0102 .0089 .0018 .0047 .0050 .0058 .0025 .1174 .0269 .0870 .0557 .0548 .O-VW .0662 .0860 .0784 .1063 .0642 .0805 .0833 .0477 .0855 .0881 .0878 ' .0367 82.04 24.45 94.26 91.01 92.10 85.45 86.76 93.89 94.46 95.08 93. 18 , 88.75 i ' 90.35 96.36 . 94.79 94.63 93.80 93.62 80.69 23.34 93.96 90.99 91.35 84.25 84.80 93.25 92.74 94.93 92.50 88.21 89.50 96.33 94.28 94.14 93.56 93.12 83.96 1635 1202 Experiment No. 95: Beef round, cooked in water 2 hours, cut into quarter-inch cubes Digested 4 hours. Experiments Nos. 7-11: Beef round- Raw 26.20 94.40 1203 Pan broiled 91.06 1204 Fried in hot lard 92.79 1205 1206 1210 Cooked in water 2 hours Cooked in water 5 hours Experiments Nos. 12-16: Beef round, lean- Raw 1 87. 12 89.39 1 94.36 1211 1212 1215 Cooked in water 2 hours Cooked in water 5 hours Pan broiled 95.38 i 95. 19 94.05 1219 Fried in hot lard 89.25 1235 Experiments Nos. 17-21: Beef round. lean- Raw 91.43 1238 Pan broiled 96.43 1241 Fried in hot lard 95. 72 1242 1243 1279 Cooked in water 1 hour Cooked in water 5 hours 1 Experiments Nos. 22-26: Beef sirloin, very fat, broiled, 1 underdone 95.28 . 93.97 ' 94. 36 85 Table 35. — Results ohtained in artificial digestion of samples of different cuts of beef,' raw and cooked in different ways — Continued. Labo- ra- tory No. 1280 1281 1282 1283 1287 1300 1302 1303 1305 1306 1307 1309 1314 1313 1331 1330 1348 1347 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1399 1400 1401 1402 1403 1462 1463 1464 1465 Description of sample. Digested 4 hours — Continued. Beef sirloin, very fat, broiled, well done , Beef sirloin, very fat, broiled, under- done Do Do :..., Average of 5. Experiments Nos. 27-28: Beef shoulder, very fat, cooked in water 2 hours Beef shoulder moderately fat, raw. Experiments Nos. 29-31: Beef sirloin, verv fat, raw Do .' Do Average of 3. Experiments Nos. 32-34: Beef sirloin, very fat, broiled. Do Do Average of 3. Experiments Nos. 35-36: Beef round, lean, raw Beef round, lean, pan broiled, well done Experiments Nos. 37-38: Beef round, lean, raw Beef round, lean, fried in hot lard, well done Experiments Nos. 39-40: Beef round, lean, raw Beef round, lean, roasted, well done Experiments Nos. 41-45: Beef round, lean — Raw Pan broiled Cooked in water 2 hours, well done Fried in hot lard, well done Roasted, well done Experiments Nos. 46-50: Beef round, lean — Raw Pan broiled Cooked in water 2 hours Fried in hot lard Roasted Experiments Nos. 51-55: Beef, different cuts, all cooked in water 2 hours — First cut ribs, very fat Leg bone, moderately fat Second cut, neck, moderately fat Flank, very fat Round, rather fat Experiments Nos. 67-70: Beef,|different cuts, all cooked in warer 2 hours — Leg bone Second cut, neck Flank, well done Round, well done Num- ber of tests in av- erage. Nitrogen in- Meat. Gram. 0.0688 .0537 .0555 .0843 .0603 . 0965 . 1146 .0710 .0574 .0602 .0629 .0907 .0809 .0965 .0894 .0884 .0928 .0932 .1168 .1034 .1066 .0909 .0863 .1035 .0913 .0940 .0847 .0733 .0990 .1045 .0875 .0823 .0946 . 0751 .0721 .0953 .0765 .0481 .0580 .1038 Undi- gested por- tion. Gram. 0.0063 .0093 .0038 .0074 .0059 .0085 .0106 .0051 .0041 .0032 .0041 .0091 .0068 .0089 .0083 .0051 .0084 .0054 .0115 .0070 .0062 .0056 .0044 .0105 .0079 .0105 .0091 .0073 .0123 .0150 .0067 .0092 .0137 .0091 .0107 .0072 .0068 .0069 .0106 .0075 Digest- ed por- tion. Gram. 0. 0625 .0444 .0517 .0769 .0544 .0880 .1040 .0659 .0533 .0570 .0587 .0816 .0741 .0876 .0811 .0833 .0844 .0878 .1053 .0964 .1004 .0853 .0819 .0930 .0834 .0835 .0756 .0660 .0867 .0895 .0808 .0731 .0809 .0660 .0614 .0881 .0697 .0412 .0474 .0963 Proportion of total ni- trogen in digested portion. Aver- age. Per ct. 90.84 82.68 93.15 91.22 90.30 91.19 90.75 92.82 92.86 94.68 93.45 89.97 91.59 90.78 90.78 94.23 90.95 94.21 90.15 93.23 94.19 93.84 94.90 89.86 91.35 88.83 89.26 90.04 87.58 85.65 92.34 88.82 85.52 87.88 85.16 92. 44 91.11 85.65 81.72 92.77 Mini- mum. Per ct. 89.99 92.73 90.93 90.87 90.35 92.43 92.33 94.40 89.26 90.96 90.10 94. 03 90.10 92.35 89.27 92.92 93. 69 93.05 94.27 89.76 90.82 88.11 89.09 89.15 86.22 84.41 90.44 87.43 84.35 87.08 82.86 90.19 90.33 83.29 80.54 91.86 Ma.xi- mum. Per ct. 91.74 93.29 91.58 91.88 91.21 93.61 93.42 94.97 91.03 92.32 91.40 94.44 91.40 95.61 90.84 93.60 94.56 94.18 95.73 90.81 91.63 90.64 89.40 90.90 89.57 86.51 93.80 89.67 87.56 88.75 87.87 94.74 91.82 88.57 82.88 93.52 86 Table 35.- — ncsiills ohlained in arlijicial digestion of samples of (Uffrrent evts of lieef raw and eooked in differenl vays — Continued. Labo- Description of sample Num- ber of tests in av- erage. Nil Meat. Gram. 0. 0816 .0717 .0648 . 0634 . 0709 .0843 .0939 .1010 .0719 .0869 . 095() .0719 . 0935 .0931 . 0923 .0659 .0708 .0418 .0475 .0787 .0910 .1153 .0757 .0662 .0676 .rogen in — Proportion of total ni- trogen in digested portion. tory No. Undi- gested por- tion. Digest- ed por- tion. . Aver- age. Mini- mum. Maxi- mum. 1202 Digested G /lours. Experiments Nos. 7-11: T5eef round- Raw 4 4 4 4 3 4 3 4 3 3 3 3 4 4 4 2 3 3 3 3 3 4 3 4 3 Gram. 0. 0039 .0033 . 0032 .0071 . 00.50 .0041 .0031 .0065 .0037 .0084 .0048 .0022 .0038 .0041 .0033 .0041 .0046 .0040 . 0026 .0053 .0081 .0074 .0038 .0039 .0011 Gram. 0. 0777 .0684 .0616 .0563 . 0('i.59 .0802 .0908 .0945 .0682 .0785 .0908 .0697 .0897 .0890 .0890 .0618 .0662 . 0378 .0449 . 07.34 .0829 .1079 .0719 .0623 .0665 Per ct. 95.22 95.40 96.06 88.80 92.95 95.14 96.70 93.56 94.85 90. 33 94.98 96.94 95.94 95.60 96.42 93.78 93.50 90.43 94.53 93.27 91.10 93.59 94.98 94.11 98.37 Per ct. 94.17 94.76 94.21 87.48 92.09 94.65 96.08 91.22 94.47 89.46 94.18 96. 65 95.67 95.49 96.04 93.67 92.78 89.76 94.03 93.18 89.82 93.53 94.13 93.13 98.26 Per ct. 95.68 1203 Pan liroiled 96.36 1204 Fried in hot lard 95. 76 1205 1206 1210 Cooked in water 2 hours Cooked i ii water 5 hours Experiments Nos. 12-16: Beef, round, lean- Raw 89.63 93.44 95. 30 1211 1212 1215 Cooked in water 2 hours Cooked in water 5 hours Pan broiled . 96.96 95.17 95.11 1219 Fried in hot lard 91.08 1235 Experiments Nos. 17-21: Beef, round, lean — Raw 95.71 1238 Pan 1) roiled 97.22 1241 Fried in hot lard 96.13 1242 1243 1279 Cooked in water 1 hour Cooked in water 5 hours Experiments Nos. 22-26: Beef sirloin, very fat, broiled, un- derdone 95.72 97.36 93.74 1280 Beef sirloin, very fat, broiled, well done 93.96 1281 Beef sirloin, very fat, broiled, un- derdone .- 90.97 1282 Do. 95.06 1283 Do 93.35 1287 Experiments Nos. 27-28: Beef shoulder, very fat, cooked in water 2 hours 92.31 1300 1302 1303 Beef shoulder, moderately fat, raw Experiments Nos. 29-31 : Beef sirloin, verv fat, raw Do ' 93.73 96.05 95.29 1305 Do. . . . 98.63 Averaee of 3 .0698 .0029 .0669 95.82 Experiments Nos. 32-.34 : Beef sirloin, very fat, broiled Do ■. 1306 1307 3 4 4 . 0760 .0772 .0948 .0055 .0051 .0062 .0705 .0721 .0886 92.76 93.39 93.46 92.61 93.14 92.52 92.93 93.60 1309 Do 94.79 Average of 3 .0827 .0056 .0771 93.20 Experiments Nos. 35-36: Beef round, lean, raw 1314 4 3 3 3 4 4 4 3 3 3 4 4 3 4 3 3 .1045 .1127 .0933 .1001 .0904 .1015 . 0966 .1067 .0892 .0927 .0099 .0951 .0704 .0955 .0945 .1093 .0053 .0081 .0051 .0085 .0046 .0054 . 0037 .0047 .0042 .0002 .0055 .0078 .0042 . 0052 .0110 .0077 .0992 .1046 .0882 .0916 .0858 .0961 .0929 .1020 .0850 .0865 .0940 .0873 . 0662 .0903 .0835 .1016 94. 93 92.81 94.53 91.51 94.91 94.68 96.17 95.60 95.2^ 93.31 94.47 91.80 94.03 94.55 88.36 92.95 94.41 92.44 94.47 91.20 94.06 94.22 95. 67 94. 96 94.88 93.18 94.01 91.61 91.49 y3. 93 86. 17 92.34 95.39 1313 Beef round, lean, pan broiled, well done 93. 20 1331 Experiments Nos. 37-38: Beef round, loan, raw 94. 68 1330 Beet round, lean, fried in hot lard, well done 91.89 1348 Experiments Nos. 39-40: Beef round, lean, raw. 95.46 1347 Beef round, lean, roasted, well done - . . 94.96 1388 Experiments Nos. 41-45: Beef round, lean — Raw 96. 53 1389 Pan broiled . . . . 96.59 1390 Cooked in water 2 hours, well done 95. 62 1391 1392 Fried in hot lard, well done Roasted , well done 93.38 95. 32 1393 Experiments Nos. 46-50: Beef round, lean—. Raw 91. 80 1394 Pan broiled 95.90 1395 1396 Cooked in water 2 hours Fried in hot lard 95. 28 89. 69 1397 Roasted 94.00 87 Table 35. — Results obtained in artificial digestion of sainples of different cuts of beef,' raw and cooked in different ways — Continued. Labo- Description of sample. Num- ber of tests in av- erage. Ni trogen in — Proportion of total ni- trogen in digested portion. ra- tory No. Meat. Undi- gested por- tion. Digest- ed por- tion. Aver- age. Mini- mum. Maxi- mum. 1399 1400 1401 1402 1403 1461 1462 Digested 6 hours— Conthmed. Experiments Nos. 51-55: Beef, different cuts, all cooked in water 2 hours — First cut ribs, very fat Leg bone, moderately fat Second cut, neck, moderately fat Flank, very fat Round, rather fat Experiments Nos. 66-70: Beef, different cuts, all cooked in water 2 hours- First cut ribs, underdone Leg bone 3 4 3 3 2 3 2 3 4 4 3 2 4 4 4 4 3 4 3 2 3 4 4 2 4 4 3 4 3 Gram. 0. 0695 .0855 .0660 .0741 .0801 .0547 .0830 .0522 .0535 .0958 .1303 .1439 .0833 .0739 .0679 .0680 .0722 • .0821 .0886 .1189 .0836 .0905 .0828 .0613 .0902 .0954 .0730 .1006 .0989 Gram. 0.0059 .0084 .0054 .0095 .0058 . 00.57 .0061 .00.57 .0076 .0046 .0077 .0872 .0025 . 0026 .0025 .0031 .0026 .0026 .0029 .0056 .0038 .0051 .0030 .0020 .0020 .0027 .0022 .0034 .0027 Gram. 0. 0636 0771 .0606 . 0646 .0743 .0490 .0769 .0465 .0459 .0912 .1226 .0567 .0808 .0713 . 0654 .0649 .0696 .0795 .0857 .1133 .0798 .0854 .0798 .0593 . 0882 .0927 .0708 .0972 .0962 Per ct. 91.51 90.18 91.82 87.18 92.76 89.58 92.65 89.08 85.79 95. 20 94.09 39. 40 97.00 96.48 96.32 95.44 96.40 96.83 96. 73 95.29 95 45 94.36 96.38 96.74 97.78 97.17 96.99 96.62 97.27 Per ct. 90.31 89.24 90.43 86.76 91.98 88.28 92. 63 88.59 84.38 94.61 93.89 3.5. 17 96.53 96.02 96.03 95.09 95.93 96.41 96. 56 94.94 95.34 94.14 95.71 96.51 97.38 97. 03 96.73 95.99 97.04 Per ct. 92.36 91.33 93.76 89.55 93.50 90.69 92.67 1463 Second cut neck 89.74 1464 Flank, well done 86.90 1465 Round, well done 95.92 1634 Experiment No. 94: Beef round, cooked in water 2 hours, ground twice in a sausage mill 94.63 1635 Experiment No. 9.'i: Beef round, cooked in water 2 hours, cut into quarter-inch cubes 42.03 1202 Digested S4 hours. Experiments Nos. 7-11: Beef round- Raw . . 97.74 1203 Pan broiled 97.04 1204 Fried in hot lard 96.54 1205 1206 1210 Cooked in water 2 hours Cooked in water 5 hours Experiments Nos. 12-16: Beef round, lean- Raw 95.64 96.63 97.20 1211 1212 1215 Cooked in water 2 hours Cooked in water 5 hours Pan broiled 96.90 95.53 95.41 1219 Fried in hot lard 94.64 1235 Experiments Nos. 17-21: Beef round, lean- Raw 96.95 1238 Pan broiled 97.04 1241 Fried in hot lard 98.40 1242 1243 1287 Cooked in water 1 hour Cooked in water 5 hour's Experiments Nos. 27-28: Beef shoulder, very fat, cooked in water 2 hours. . . . 97.28 97.21 97.37 1300 Beef shoulder, moderately fat, raw. Experiments Nos. 29-31: Beef sirloin, very fat, raw 97.61 1302 2 3 2 .0775 .0557 .0732 .0007 .0007 .0036 .0768 .0550 .0696 99.10 98.74 95.08 98. 36 97.80 95.00 100.00 1303 Do 99.09 1305 Do 95.16 Average of 3 .0688 .0017 .0671 97.64 Experiments Nos. 32-34: Beef sirloin, very fat, broiled Do 1306 1307 3 2 2 .0910 .0701 .0976 .0037 .0025 .0022 .0873 .0676 .0954 95.93 96.51 97.75 95.63 96.43 96.64 96.07 96.59 1309 Do 98.52 Average of 3 .0862 .0028 .0834 96.73 Experiments Nos. 35-36: Beef round, lean, raw 1314 4 4 .1158 .0979 .0032 .0034 .1126 .0945 97.24 96.53 96.94 96.20 97.44 1313 Beef round, lean, pan broiled, well done 96.75 88 Table 35. — Results obtained inartificial digestion of samples of different cuts of beef, raw and cooked in different ways — Continued. Labo- Description of sample. Num- ber of tests in av- erage. Nitrogen in— Proportion of total ni- trogen in digested portion. tory No. Meat. Undi- gested por- tion. Digest- ed por- tion. Aver- age. Mini- mum. Maxi- mum. 1331 1330 Digested M hours — Continued. Experiments Nos. 37-38: Beef round, lean, raw Beef round, fried in hot lard, well done 3 4 Gram. 0.0977 .12:<9 Gram. 0.0025 .0044 .0038 .0057 .0019 .0014 .0044 .0022 .0022 .0034 .0022 .0023 ■•■ . 0037 .0024 Gram. 0.0952 .1195 .0892 ,1145 .0832 .0768 .1004 .0782 .0808 .0954 .0742 .0725 .0991 .0917 Per ct. 97.44 96.45 9.i. 91 95.34 97.77 98.21 95. 80 97.26 97.35 96.56 97.12 96.93 96.40 97.45 Perct. 97.40 96.23 95.59 94.87 97.66 97.89 95. 05- 96.76 96.65 96.49 96.67 96.83 96.00 97.26 Per ct. 97.50 96 70 1348 Experiments Nos. 39-40: Beef round, lean, raw 4 -09.'?n 96 17 1347 Beef round, lean, roasted, well done ■. 3 4 3 3 4 3 4 3 4 4 4 .1202 .0851 .0782 .1048 .0804 .0830 .0988 .0764 .0748 .1028 .0941 95 84 1388 Experiments Nos. 41-45: Beef round, lean- Raw 97 92 1389 Pan broiled 98.46 1390 Cooked in water 2 hours, well done 96 80 1391 1392 Fried in hot lard, well done . . . Roasted, well done. 97. 62 97 G6 1393 Experiments Nos. 46-50: Beef round, lean- Raw 96 62 1394 Pan broiled 97.92 1395 1396 Cooked in water 2 hours Fried in hot lard 97.20 96 89 1397 Roasted 97 55 Experiment No. 92: Beef ribs, very fat, roasted Do 1589 1590 2 3 .0761 .0580 .0059 .0028 .0702 .0552 92.25 95.11 91.54 95.06 92.85 95.16 Average of 2 .0671 .0044 .0627 93.68 Experiment No. 93: Beef ribs, very fat, roasted Do 1591 1595 3 3 .0711 .0581 .0047 .0033 .0664 .0548 93.39 94.32 92.78 93.78 94.31 95 14 Average of 2 .0646 .0040 .0606 93.86 Average of 6 '. .0683 .0040 .0643 94.21 Experiment No. 94: Beef ribs, very fat, raw 1611 3 3 2 3 3 3 .0662 .0488 .0679 .0523 .0756 .0596 .0056 .0027 .0025 .0033 .0040 .0029 .0606 .0461 .0654 .0490 .0716 .0567 91.54 94.47 96. 32 93. 69 94.71 95.13 91.31 94.09 95.44 92.87 94.41 95.00 91.67 1615 1612 Beef ribs, very fat, roasted Experiment No. 95: Beef ribs, very fat, raw 94.71 97.01 1614 1613 Beef ribs, very fat, roasted Experiment No. 96: Beef ribs, very fat, raw 94.47 95.02 1616 Beef ribs, very fat, roasted Experiment No. 97: Beef ribs, very fat, roasted Do 95.41 1525 1561 3 3 3 .0582 .0800 .0523 .0028 .0036 .0028 .0554 .0764 .0495 95.19 95.50 94.65 94.75 94.60 94.26 95.87 96.03 1617 Do. 94 71 Average of 3 .0635 .0031 .0604 95.11 Experiment No. 94: Beef round, cooked in water 2 hours, ground twice in a sausage mill 1634 4 3 2 3 3 2 3 .1088 .0996 .0796 .0745 .0898 .0590 .0848 .0034 .0108 .0032 .0026 .0064 .0042 .0056 .1054 .0888 .0764 .0719 .0834 .0548 .0792 96.87 89. 16 95.98 96.51 92.87 92.88 93.40 96. 43 86.81 95.12 95.94 91.92 90.96 92.68 97.18 1635 Experiment No. 95: Beef round, cooked in water 2 hours, cut into quarter-inch cubes 91.97 1399 1400 1401 Experiments Nos. 51-55: Beef, different cuts, all cooked in water 2 hours — First cut ribs, very fat Leg bone, moderately fat Second cut neck, moderately fat 96.73 96.94 94.03 1402 Flank, very fat 94.71 1403 Round, rather fat 93.73 89 Table 35. — Results obtained in artificial digestion of samples of different cuts of beef, raw and cooked in different ways — Continued. Labo- Description of sample. Num- ber of tests in av- erage. Nitrogen in— Proportion of total ni- trogen in digested portion. ra- tory No. Meat. Undi- gested por- tion. Digest- ed por- tion. Aver- age. Mini- mum. Maxi- mum. 1461 1462 Digested 34 feoMrs— Continued. Experiments Nos. 66-70: Beef, different cuts, all cooked in water 2 hours- First cut ribs, underdone Leg bone 2 4 Oram. 0. 0607 .0841 Gram. 0. 0032 .0029 .0027 .0026 .0032 .0027 .0020 .0024 .0036 .0018 .0030 .0017 .0027 .0024 .0029 Gram. 0. 0575 .0812 .0560 .0572 .0974 .0505 .0575 .0443 .0536 .0317 .0530 .0537 .0489 .0500 .0632 Per ct. 94.73 96.55 95.40 95.65 96.82 94.92 95.67 94.86 93.71 94.63 94.64 96.93 94.77 95.42 95.51 Per ct. 94.43 96.51 Per ct. 94.97 96.78 1463 Second cut neck 3 . 0587 95.11 ; 9.5.75 1464 Flank, well done 3 4 1 4 2 3 3 3 3 2 3 2 .0598 .1006 .0.532 .0601 .0467 .0572 .0335 .0560 .0554 .0516 .0524 .0661 95.29 96.10 96.14 1465 Round, well done. 97.12 1520 Experiment No. 81: Beef ribs, very fat, raw .1537 1521 Beef ribs, very fat, roasted Experiment No. 82: Beef ribs, very fat, raw. 94.75 94.46 92.75 93.03 94.25 96.40 94.61 95.09 95.32 96.90 95.09 1536 1522 Beef ribs, very fat, roasted Experiment No. 83: Beef ribs, very fat, raw 94.85 96.29 1538 1535 Beef ribs, very fat, roasted Experiment No. 84: Beef ribs, very fat, raw. 95.35 97.45 1539 1541 1540 Beef ribs, very fat, roasted Experiment No. 85: Beef ribs, very fat, raw Beef ribs, very fat, roasted Experiment No. 91: Beef ribs, very fat, roasted Do 94.73 95.80 95.70 1587 1588 4 1 .0666 .0797 .0033 .0039 .0633 .0758 95.05 95.11 94.31 95.27 Average of 2 » . . .0732 .0036 .0696 95.08 EXPERIMENTS WITH MUTTON. The work with mutton consisted of a study of the relative ease of digestion of different cuts from the same animal, which was a wether about 2 years old when slaughtered. Five different cuts were used. No. 1424 was a shoulder, very fat; No. 1425 was a flank piece, very fat; No. 1426 was a leg, moderately fat; No. 1427 was a piece of loin, very fat; and-No. 1428 was a rib piece, very fat. Each of these was cooked in water that was kept boiling for ten minutes, and then at 80°-85° for two hours. The experiments with these pieces of meat, Nos. 56 to 60, are given in Table 36. 90 Table 3G. — Results obtained in artificial digestion of different cuts of mutton, all cooked in the same manner. Lab- ora- tory No. 1424 1425 1426 1427 1428 1424 1425 1426 1427 1428 1424 1425 1426 1427 1428 1424 1425 1426 1427 1428 1424 1425 1426 1427 1428 Description of sample. Digested 1 hour. Experiments Nos. 56-60: Mutton, different cuts, all cooked in water 2 hours- Shoulder Flank Leg Loin Ribs Digested i tiours. Experiments Nos. 56-60: Mutton, different cuts, all cooked in water 2 hours- Shoulder Flank Leg Loin Ribs Digested 4 hours. Experiments Nos. .')6-60: Mutton — Shoulder Flank Leg Loin ■. .. Ribs Digested 6 hours. Experiments Nos. 56-60: Mutton — Shoulder Flank Leg Loin Ribs Digested 34 hours. Experiments Nos. 56-60: Mutton — Shoulder Flank Leg Loin Ribs..... Num- ber of tests in av- erage. Nitrogen- Proportion of total ni- trogen in digested portion. In In undi- meat. gested residue. Gram. Gram. 0. 0760 0.0135 .0647 .0193 .0686 .0100 . 0577 .0140 . 0557 .0111 .0765 .0118 .0715 .0126 . 0618 . 0070 . 0555 .0095 .0552 .0091 \ .0699 .0087 .0571 .0091 .0669 .0046 . 0552 .0062 .0668 .0063' .0721 .0049 .0694 .0087 .0687 .0035 .0436 .0042 .0615 .0055 .0801 .0037 .0618 .0037 .0720 .0014 . 0548 .0020 .0672 .0029 In di- I gested , Aver- por- age. tion. Gram. 0. 0625 .0454 .0586 .0437 .0446 .0647 .0589 . 0548 .0460 .0461 .0612 .0480 .0623 .0490 .0605 .0672 .0607 .0652 .0394 .0560 .0764 .0581 .0706 .0528 .0643 Per ct. 82.24 70.17 8.5.42 75. 74 80.07 84.58 82.38 88.67 82.88 83.51 87.55 84.06 93.12 88.77 90.57 93.20 87.46 94.91 90.37 91.06 95.38 94.01 98.06 96.35 95.68 Mini- mum. Per ct. 68.01 84.24 74.30 79.74 84.25 80.75 88.07 81.01 82.64 82.15 92.62 88.01 87.24 92.87 87,19 93.26 88.79 89.06 95.18 93.52 97.27 96.01 94.54 Maxi- mum. Per ct. 71.39 87. 05 76.83 80.18 84.85 83.26 89.36 84.05 84.27 85.08 93.99 89.35 92.60 93.73 87.95 96.76 93.13 93.20 95.59 94.27 98.94 96.63 96.70 EXPERIMENTS WITH PORK. The work with pork inchided experiments with different cuts from the same animal, all cooked in the same way, and also tests with the same cut from different animals, both raw and roasted. The samples used are here described. Experiments Nos. Gl to 65 were made with different cuts of pork from a very fat animal about 9 months old when slaughtered. No. 1430 was a belly cut, known locally .as a flitch piece; No. 1432 was fresh ham; No. 1433 was fresh shoulder, and No. 1434 was a back cut. Each piece of meat was cooked in water, which was kept boiling for ten minutes and then at 80° to 85° for two hours. Experiment No. 71 was made with fresh ham from a corn-fed hog 8 months old. One piece (No. 1482) was not cooked and one piece (No. 1483) was roasted. 91 Experiment No. 72 was made with fresh ham from a corn-fed hog about 8 months old. One piece (No. 1485) was not cooked and the other piece (No. 1484) was roasted. Experiment No. 73 was made with fresh ham from a corn-fed hog about 8 months old. One piece (No. 1487) was not cooked and the other piece (No. 1486) was roasted. Experiment No. 74 was made with a fresh ham from an animal about 8 months old that had been fed on hominy and gluten meal. One piece (1488) was uncooked and the other piece (1489) was roasted. Experiment No. 75 was made with fresh ham from a Duroc-Jersey hog about 8 months old that had been fed on hominy and gluten meal. One piece (1490) was not cooked and the other piece (1491) was roasted. Experiment No. 76 was made with fresh ham from a Duroc-Jersey hog al^out 8 months old that had been fed on hominy and gluten meal. One piece (1492) was not cooked and the other piece (1493) was roasted. Experiment No. 77 was made with fresh ham from a Duroc-Jersey hog about 9 months old, fed on corn and clover.' One piece (1505) was not cooked and the other piece (1504) was roasted. Experiment No. 78 was made with fresh ham from a Duroc-Jersey hog about 8^ months old, fed on corn and clover. One piece (1507) was uncooked and the other piece (1506) was roasted. Experiment No. 79 was made with fresh ham from a Duroc-Jersey hog fed on corn and clover. One piece (1510) was uncooked and the other piece (1511) was roasted. Experiment No. 80 was made with fresh ham fi'om a Yorkshire hog. One piece (1515) was not cooked and the other piece (1514) was roasted. Experiment No. 86 was made with fresh ham from a Duroc-Jersey hog about 8 months old, fed on peas, oats, and l^arley. One portion (1542) was vmcooked and the other portion (1545) was roasted. Experiment No. 87 was made with fresh ham from a Duroc-Jersey hog about 8 months old, fed on peas, oats, and barley. One portion (1543) was uncooked and the other portion (1558) was roasted. Experiment No. 88 was made with fresh ham from a Yorkshire hog about 8 months old, fed on peas, oats, and barley. One portion (1544) was uncooked and the other portion (1559) was roasted. Experiment No. 89 was made with two portions (1573 and 1574; of roasted ham from a Duroc-Jersey hog about 8 months old, fed on peas, oats, and barley. Experiment No. 90 was made with two portions (1575 and 1580) of roasted ham from a Yorkshire hog about 8 months old fed on corn. The data of the experiments are given in Table 37. Table 37. — Results obtained in artificial digestion of cuts of fresh pork, raw and cooked. Labo- ra*" tory No. 1430 1431 1432 1433 1434 Description of sample. Digested 1 hour. Experiments Nos. 61-65: Pork, different cuts, all cooked in water 2 hours — Belly Middle cut Ham Shoulder Pack Num- lier of tests in av- erage. Nitrogen in- Meat. Gram. 0. 0578 .0724 .0631 .0759 .0667 Undi^ gested por- tion. Gram. 0. 0144 .0167 .0084 .0115 .0064 Digest- ed por- tion. Gram. 0. 0434 .0557 .0547 . 0644 .0603 Proportion of total ni- trogen in digested portion. Aver- Mini- Maxi- age. mum. mum. Per ct. Per ct. Per ct. 75.09 73. 88 75.65 7f). 93 76. 78 77.06 86.69 85.97 87.74 84. 85 84.45 85. 44 90.40 90.04 91.05 92 Table 37. — Results obtained in artificial digestion of cuts of fresh pork, raw andcoolced- Continued. Labo- ra- tory No. 1430 1431 1432 1433 1434 1482 1483 1485 1484 1487 1486 1488 1489 1490 1491 1492 1493 1505 1504 1507 1506 1510 1511 1515 1514 1542 1545 1543 1558 1544 1559 1573 1574 1575 1580 Description of sample. 1430 1431 1432 •1433 1434 Digested Z hours. Experiments Nos. 61-65: Pork, different cuts, all cooked in water 2 lioiirs- Belly Middle cut Ham Shoulder Back Experiment No. 71: Fresh ham, raw Fresh ham, roasted ,. . . Experiment No. 72: Fresh ham, raw Fresh ham, roasted Experiment No. 73: Fresh ham, raw Fresh ham, roasted Experiment No. 74: Fresh ham, raw Fresh ham. roasted Experiment No. 75: Fresh ham, raw Fresh ham, roasted E.xperiment No. 76: Fresh ham, raw Fresh ham, roasted Experiment No. 77: Fresh ham, raw '. ... Fresh ham, roasted Experiment No. 78: Fresh ham, raw Fresh ham. roasted Experiment No. 70: Fresh ham, raw Fresh ham, roasted Experiment No. 80: Fresh ham, raw Fresh ham, roasted Experiment No. 86: Fresh ham, raw Fresh ham, roasted Experiment No. 87: Fresh ham, raw Fresh ham, roasted Experiment No. 88: Fresh ham, raw Fresh ham, roasted Experiment No. 89: Fresh ham, raw Fresh ham, roasted Experiment No. 90: Fresh ham, roasted. Do Average of 2 Digested 4 hours. Num- ber of tests in av- erage. Experiments Nos. 61-65: Pork, dilTcrent cuts, water 2 hours — Belly Middle cut Ham Shoulder Back all cooked in Nitrogen in — Meat. Gram. 0. 0624 .0538 .0722 .0674 . 0606 .0422 .0896 .0488 .0579 . 0599 . 0885 .0690 .0605 .0686 . 0869 .0707 . 0559 .0628 .0676 .0661 .0763 . 0677 .0743 . 0753 .0736 . 0643 .0618 . 0669 .0745 .0792 . 0605 .0781 .0763 Undi- gested (Por- tion. .0910 . 0:125 .0768 .0590 .0549 .0618 .0685 .0633 Gram. 0.0102 .0084 .0071 .0072 .0037 .0043 .0129 . 0057 .0085 .0047 .0108 . 0058 . OOC.O \0044 . 0204 .0113 .0128 .0094 . 0069 .0073 . 0065 .0085 . 0055 .0110 .0060 .0083 .0087 .0092 . 0157 .0074 .0080 .0080 .0073 Digest- ed por- tion. . 0102 .0095 .0099 . 0067 .0059 .0035 .0039 .0029 Gram. 0. 0522 .0454 .0651 .0602 .0569 .0379 .0767 . 0431 .0495 . 0552 .0777 . 0632 .0545 .0642 .0665 .0594 .0431 .0534 .0607 . 0588 .0698 .0592 .0688 .0643 .0676 . 0560 .0531 . 0577 .0588 .0718 . 0525 .0701 .0690 . 0530 .0669 . 0523 .0490 .0583 .0646 .0604 Proportion of total ni- trogen in digested portion. Aver- age. Per ct. 83. 65 84.39 90.17 89.32 93.89 89.81 85.60 88.32 85.49 92.15 87.80 91.59 90.08 93.59 76.52 84.02 77.10 85.03 89.79 88. 96 91.48 87.44 92.60 85.39 91. 85 87.09 85.92 86.25 78.92 90.66 86.78 89.76 90.43 Mini- mum. 88.79 84.80 86.80 88. 64 89.25 94.34 94.31 95.42 Per ct. 82. 90 83.97 89.23 87.85 92.83 89. 05 84.50 87.08 85.01 91.84 87.62 91.30 89.06 92.03 75. 17 83. 05 76.50 84.41 88. 91 88.59 90.24 87.24 92.21 82.05 91.80 86.46 83.70 85. 09 78. 73 89.94 85.10 87.01 90.03 Maxi- mum. 88.53 84.36 88.26 88.11 93.88 93.93 95.14 Per ct. 84.67 84.91 91.51 91.11 95. 18 90. 26 86.58 89.71 85.58 92.29 88.09 91.72 90.66 94.89 78.91 85.24 77.94 85.94 90.77 89.61 92.34 87.79 92.82 88.18 91.89 87.40 88.79 87.64 79. 16 91.61 88.53 91.04 90.88 88. 98 85.44 88.81 90.07 94.82 94.58 95.51 93 Table 37. — Results obtained in artificial digestion of cuts of fresh pork, raw and cooked- Continued. Labo- ra- tory No. Description of sampln. Digested 6 hours. Experiments Nos. 61-65: Pork, different cuts, all cooked in water 2 hours — 1430 Bellv 1431 ■ Middle cut 1432 "^ Ham 1433 Shoulder 1434 Back '. Digested 24 hours. Experiments Nos. 61-65: Pork, different cuts, all cooked in water 2 hours— 1430 Belly 1431 ! Middle cut 1432 I Ham 1433 Shoulder 1434 j Back Experiment No. 71: 1482 I Fresh ham, raw 1483 Fresh ham, roasted Experiment No. 72: 1485 Fresh ham, raw 1484 1 Fresh ham, roasted Experiment No. 73: 1487 I Fresh ham, raw 1486 ■ Fresh ham, roasted Experiment No. 74: 1488 ! Fresh ham, raw 1489 Fresh ham, roasted I Experiment No. 75: 1490 Fresh ham, raw 1491 Fresh ham, roasted Experiment No. 76: 1492 I Fresh ham, raw 1493 I Fresh ham, roasted Experiment No. 77: 1505 j Fresh ha:n, raw 1504 I Fresh ham. roasted Experiment No. 78: 1507 j Fresh ham, raw 1506 I Fresh ham, roasted Experiment No. 79: 1510 I Fresh ham, raw 1511 ; Fresh ham, roasted Experiment No. 80: 1515 I Fresh ham, raw : . . . 1514 I Fresh ham, roasted i Experiment No. 86: 1542 I Fresh ham, raw 1545 ', Fresh ham, roasted j Experiment No. 87: 1543 ' Fresh ham, raw 1558 Fresh ham, roasted ' Experiment No. 88: 1544 ' Fresh ham, raw 1559 j Fresh ham, roasted I Experiment No. 89: 1573 ! Fresh ham, raw 1574 Fjesh ham, roasted ; Experiment No. 90: Num- ber of tests in av- erage. 1575 1580 Fresh ham, roasted. Do Average of 2 . Nitrogen in- Proportion of total ni- trogen in digested portion. Undi- Meat. I %l^ tion. Gram. 3 0. 0626 4 . 0674 3 . 0591 3 .0673 2 .0653 .0721 .0644 .0721 .0626 .0850 .0566 .0475 .0541 .0669 .0697 .0556 .0650 .0753 .0808 .0701 .0573 .0709 .0523 .0702 .0660 .0657 .0707 .0759 .0801 .0831 .0664 .0791 .0827 .0773 .0621 .0720 .0747 Gram. 0. 0043 . 0045 .0026 .0030 .0029 .0827 .0524 .0676 .0022 .0022 .0021 .0016 .0022 .0022 .0040 .0014 .0023 .0026 .0031 .0020 .0026 .0024 .0041 .0028 .0027 .0028 .0023 .0024 .0026 .0021 .0028 .0029 .0032 .0050 .0018 .0060. .0034 .0028 .0025 .0023 .0029 ?^fnr'' Aver- Gram. 0.0583 .0629 .0565 .0643 .0624 .0699 .0622 .0700 .0610 .0828 .0544 .0768 .0461 .0518 .0643 .0666 .0536 .0624 .0729 .0767 .0673 .0546 .0681 .0500 .0678 .0634 .0636 .0679 .0730 .0769 .0781 .0646 .0731 .0793 ; 0745 .0596 .0697 .0718 Mini- mum. .0030 .0030 .0197 .0494 .0030 .0646 Per ct. 93.13 93.32 95.60 95.54 95.56 96.95 96.58 97.09 97.44 97.41 96.11 95.05 97.05 95.75 96.11 95. 55 96.40 96.00 96.81 94.93 96.01 95.29 96.05 95.60 96.51 96.06 96.80 96.04 96.18 96.00 93.98 97.29 92.41 95.89 96.38 95.96 96.81 96.12 Per ct. 92.37 92. a3 95.45 95.17 95.26 96.37 94.27 95.32 Maxi- mum. 95.82 96.42 96.78 97.12 97.30 95.67 94.59 96.79 95.59 95.72 95.19 96.19 95.49 %.64 94.64 95.85 94.39 95.82 95.18 96.45 95.05 96.53 95.73 96.13 95.43 91.69 97.29 91.32 95. 38 95.16 95.68 96.64 95.45 Per ct. 93.92 94.44 95.81 95.82 95.90 98.44 96.88 97.39 97.65 97.64 96.66 95.50 97.32 95.99 96.49 95.76 %.66 %.41 97.02 95.22 96.06 96.60 96.26 95.98 96.57 96.08 97.26 96.53 96.33 96.34 95.96 97.29 94.11 96.32 97.42 96.17 96.90 96.44 96.29 93.53 96.57 95.10 94 SUMMARY AND DISCUSSION OF RESULTS. For convenience in discussion, the data of Tables 35 to 37 that are of especial significance are here summarized so as to show the different kinds and cuts of meat used, the different methods of cooking, the lengths of the digestive periods, and the average coefficients of digestibility of protein obtained. Table 38. — Summary of results of artificial digestion experiments with beef. Lab- ora- tory No. Kind of meat and method of cooking. Proportion of total protein digested digestion was continued for— when 1 hour. 2 hours. 4 hours. 6 hours. 24 hours. 1202 Beef round: Raw Per cent. 92 o51 a 62 75 73 86 84 88 78 75 89 84 82 84 78 89 81 85 76 83 83 72 77 77 86 88 80 84 79 84 88 Per cent. 94 73 75 82 87 91 92 91 87 82 91 92 90 90 91 89 86 92 88 90 84 84 84 79 92 92 88 88 82 90 90 Per cent. 94 85 87 91 92 94 94 95 93 89 90 95 94 96 95 94 90 95 91 89 89 88 90 86 92 94 91 94 90 93 94 Per cent. 95 89 93 95 95 95 97 94 95 90 95 96 96 97 96 96 95 96 93 94 92 95 94 88 93 95 93 95 92 95 95 Per cent. 97 1205 Cooked in water 2 hours 95 1206 Cooked iu water 5 hours 96 1203 Pan broiled 96 1204 Fried in hot lard 96 1210 Raw 97 1211 Cooked in water 2 hours 97 1212 Cooked in water 5 hours 95 1215 Pan broiled 95 1219 Fried in hot lard 94 1235 Raw. . 96 1242 Cooked in water 1 hour 97 1243 Cooked in water 5 hours . . 97 1238 Pan broiled 97 1241 Fried in hot lard 98 1388 Raw 98 1390 Cooked in water 2 hours 96 1389 Pan broiled 1 98 1391 Fried in hot lard 97 1392 Roasted * 97 1393 Raw 97 1395 Cooked in water 2 hours 97 1394 Pan broiled 97 1396 Fried in hot lard 96 1397 Roasted 97 1314 Raw 97 1313 97 1331 Raw 97 1330 Fried in hot lard 96 1348 Raw 96 1347 Roasted 95 Average of above S series of experi- ments: Raw 87 84 82 85 80 76 85 90 92 84 91 87 85 90 ^ 93 95 89 92 93 90 92 95 96 94 94 95 92 94 97 Cooked in water 1 hour Cooked in water 5 hours Pan broiled 97 96 96 97 Fried in hot lard 96 Roasted Beef round : Cooked in water 2 hours, ground twice in a sausage mill 97 1634 1 82 24 94 39 97 1635 Cooked in water 2 hours, cut into quar- ter-inch cubes 89 Beef sirloin: Raw 1302 79 80 82 88 87 88 93 93 95 95 94 98 99 1303 Do 99 1305 Do 95 Average of 3 80 88 93 96 98 a Not included in the average. 95 Table 38. — Summary of results of artificial digestion experiments with beef — Continued. Lab- ora- Kind of meat and method of cooking. Proportion of total proteki digested when digestion was continued for — tory No. 1 hour. 2 hours. 4 hours. 6 hours. 24 hours. 1306 Beef sirloin: B roiled Percrnt. 80 80 83 Percent. 87 86 86 Percent. 90 92 91 Percent. 93 93 93 Per cent. 96 1307 Do 96 1309 Do 98 \vera2fp of 3 81 87 91 93 97 Beef sirloin: Broiled 1279 84 76 74 81 77 86 85 80 87 82 94 91 83 93 91 94 94 90 95 93 1280 Do 1281 Do 1282 Do 1283 Do A ver;^ so of 5 78 84 90 93 Beef shoulder: Very fat, cooked in water 2 hours 1287 1300 79 84 85 86 91" 91 91 93 97 97 86 85 81 95 Beef ribs, roasted, average of 8 experiments. Beef ribs, roasted, average of 9 experiments. Beef, different cuts, all cooked in water 2 hours : First cut, rilis 95 94 1 1399 78 07 75 67 80 87 78 79 73 89 89 85 88 85 92 91 90 92 87 93 96 1400 Leg bone . 96 1401 Second cut, neck 93 1402 Flank 93 1403 Round 93 Average 73 81 88 91 94 hours : First cut, rilas 1461 78 78 70 68 83 90 93 89 86 95 95 1462 Leg bone 85 74 74 88 91 86 82 93 97 1463 95 1464 Flank 96 1465 Round Average 97 76 80 88 90 96 Mutton, different cuts, all cooked in water at 80° to 8o° C. for 2 hours: Shoulder 1424 82 70 85 76 80 86 82 89 83 84 88 84 93 89 91 93 87 95 90 91 95 1425 Flank 94 1426 Leg .... 98 1427 Loin 96 1428 Ribs. . 96 Average 79 84 89 91 96 Pork, different cuts, all cooked in water at 80° to 85° C. for 2 hours: Belly 1430 75 77 87 85 90 84 84 90 89 94 89 89 94 94 95 93 93 96 96 96 97 1431 Middle cut 97 1432 Ham 97 1433 Shoulder 97 1434 Back 97 Average 83 ,88 92 95 97 Ham, raw, average of 14 experiments 89 86 87 96 Ham, roasted, average of 14 experiments 96 Ham, roasted, average of 2 tests 95 The figures in Table 38 show what proportions of the total nitrogen contained in the meat that was treated with the artificial digestive solution were present in the material that was dissolved when the action was allowed to continue for the lengths of time specified in the 4663— Bull. 193—07 7 96 column lieatlings. For convenience in discussing results the data may be considered as representing the proportions of protein digested under the given conditions. It "svill be observed that at the end of the 24-hour periods about 97 per cent of the protein was digested and the results were practically uniform for the different samples. At the end of the 6-hour period the proportion was about 94 per cent, and at four hours 92 per cent, and the variations in the results for the different samples in either of these periods are for the most part not especially large. The proportion of protein digested in the 2-hour period was near 90 per cent and in the 1-hour period it was generally over 80 per cent, but in these periods there were considerable variations in the results for different samples. TMiatever information is to be derived from the results resrarding the relative ease of digestion of the meats cooked in different ways should be supplied by the data for these later periods. The several series of experiments with lean beef round afford excel- lent opportunity for comparison. One fact that is especially notice- able is the lack of uniformity in the results for different samples of meat digested under uniform conditions. For example, samples Nos. 1388 to 1392 were different portions of t}ie same cut of beef round from one animal, and samples Xos. 1393 to 1397 were corresponding portions of a cut from another animal. With the former sample 89 per cent of the protein of the raw meat was digested in one hour and but 83 per cent of that of the roasted meat, whereas with the latter sample the coefficient for the raw meat was only 83 per cent and that for the roasted meat was 86 per cent. With the former sample the coeffi- cient for meat cooked in water two hours was 81 per cent and with the latter only 72 per cent. Since the experimental conditions were as nearly identical as they could be made in the various series of tests, it would seem as if the fact that the two sets of samples were from different animals offers some explanation of the variations, though the coefficients for meat fried in hot lard were practically identical in both cases — 76 and 77 per cent. Averaging the results obtained in the eight series with meat from different animals tends to ec[ualize the variations observed. The coef- ficients for raw meat range from 83 to 92 per cent, and the mean of these — 87 per cent — is the same as the average of the eight tests. There was but one test with meat cooked one hour in water, and in this the coefficient was 84 per cent. With meat cooked two hours in water one test gave only 51 per cent of the protein digested, but this test was not entirely satisfactor}* and the result is not included in the average. In the other test a coefficient of 72 per cent was obtained, but in two tests the figures were 81 and 84 per cent, the average of the two being 82 per cent. In one test with meat cooked five hours in water the coefficient was 61 per cent, but this test was also not 97 entirely satisfactory. In the two other tests the figures were 82 afid 88 per cent, averaging 85 per cent. The results of the six tests with pan broiled meat ranged from 75 to 85 per cent, averaging 80 per cent, and those for the six tests with meat fried in hot lard ranged from 73 to 79 per cent and averaged 76 per cent. It is noticeable that the meat thus cooked was in each experiment less digestible in one hour than that cooked in other ways. The average of the three tests with roasted meat is 85 per cent. In general it may be said that the differences in the average results for raw meat and meat cooked in various ways are, on the whole, too small to be of much significance; and, especially in view of the varia- bleness in the results of individual tests, it seems fair to assume that so far as can be judged from these experiments there is no practical difference — at least not a constant one — in the ease of digestion of meat cooked in different ways. The only exception is that of fried meat; in this case, in each indi^ddual test, as well as in the average, the effect of the action of the digestive solution for one hour was less than in the case of any of the other samples, which would seem to indi- cate that the fried meat is perhaps not so easily digested as meat otherwise cooked. In these eight series of tests the coefficient for raw meat was in several individual cases somewhat larger than those for the cooked meats, and it is also slightly larger in the average. This might sug- gest that the raw meat was more easily digested — that is, that cooking the meat will tend to decrease the ease of digestion. One fact, how- ever, should be considered — all of the cooked meats had probably lost in cooking more or less of the water-soluble nitrogenous material that was not removed from the raw meat before digestion, and which would consequently be dissolved and form part of the digested mate- rial, and thus make the apparent digestibility of the raw meat rather larger than the actual. If allowance were made for this, the results for the raw meat, at least in the average, might perhaps be no larger than those for the cooked meat. The experiments with samples Nos. 1634 and 1635 were planned to give some idea of the effect of more or less thorough mastication upon the ease of digestion. Each sample was from the same piece of beef round, cooked in water two hours. Sample No. 1634 was ground twice in a sausage mill to represent meat somewhat thoroughly mas- ticated, whereas sample No. 1635 was cut into small pieces, about a quarter-inch cube, to represent meat less thoroughly masticated. Both samples were digested two, six, and twenty-four hours. The results obtained were several times larger with the ground meat than with that in cubes in both the two and six hour periods, and even with twenty-four hours' digestion the result with the more coarsely 98 ground meat was decidedh^ the smaller. The inference is that thor- ough chewing may have a very decided influence upon the ease of digestion of meat proteid. The results of three individual tests with raw beef sirloin agree very closely with each other in both the one and the two hour periods, and so do the results with the three corresponding tests with broiled beef sirloin; and the average of the tests with the raw beef are practically identical with the average of the results for the cooked meat in the cor- responding tests. In live other tests with broiled sirloin, however, rather wide variations were found in the results for the different sam- ples in the same period; In eight experiments beef ribs raw and roasted ^\:ere compared. In each case the meat for roasting was one portion and the meat not cooked was another portion of the same cut. With these samples digestion was carried on for only the 2 and 24 hour periods. In the results for the 24-hour period there was practical uniformity for all the samples, the variation being noticeable in the case of only one sample. In the 2-hour period the digestibility of the raw meat ranged from 82 to 91 per cent and that of the roasted meat fsom 81 to 97 per cent. In one experiment the coefficient for raw meat was 91 per cent and that for roasted meat 97 per cent, whereas in another experiment the coeffi- cient for raw meat was 90 per cent and that for roasted 82 per cent, but the average of all the tests with raw meat — 86 per cent — is prac- tically identical with that for the tests with roasted meat — 85 per cent. In nine other tests with roasted meat the range is from 73 to 88 per cent and the average 81 per cent. In one experiment five different cuts of beef from the same animal were used and in another experiment the same cuts from another ani- mal. In four cases the results with a given cut from one animal were not much different from those for the same cut from the other animal, but in the case of the leg cut the difference was quite appreciable. In the series of tests with different cuts of mutton from the same animal the difference between the maximum and minimum results in the one-hour period was quite wide, but in the results for digestion for two hours the coefficients agree fairly well with each other, the differ- ences being of little i:)ractical significance. In experiments with five cuts of pork from the same animal, all cooked in the same manner, three of the cuts — ham, shoulder, and back — agree fairly well with each other in the one-hour digestion period, but the results with the other two cuts were somewhat lower than with these. In the 2-hour period the differences are slightly smaller. There were fourteen experiments in which raw fresh ham was com- pared with roasted fresh ham when digestion had been carried on two and twenty-four hours. In each case the samples in the two tests were from the same piece of meat. In nine tests the coefficients in the 99 2-hour period were larger for the raw than for the roasted ham, and in five tests the reverse was true. The hirgest coefficient for the raw ham, 94 per cent, and the smallest for the roasted ham, 77 per cent, were found in the same experiment. The average for all the samples of raw ham is but little larger than that for the roasted ham. A comparison of the relative ease of digestion of the difi"erent kinds of meat — beef, mutton, and pork — is interesting. This can be made by averaging the results of those experiments in which different cuts of the same animal were used, since in each case the method of cook- ing the meat was the same. In all five periods the average figures for pork are the highest, those for mutton next, and those for beef last, though the difference between the beef and the mutton is smaller in the longer than in the shorter periods of digestion. On the other hand, the average of raw fresh ham in the 2-hour period is 89 per cent, that of raw beef ribs 86 per cent, and of raw beef round 90 per cent ; and that of roasted fresh ham is 86 per cent, of roasted beef ribs 85 per cent, and of roasted beef round 90 per cent. CONCLUSIONS. In twenty-three natural digestion experiments with men the same kind of meat — beef round — cooked in various ways, was eaten w4th several other common food materials in a rather varied diet. The average digestibility of the nutrients of the total diet was as follows: Protein, 93 per cent; fat, 98 per cent, and carbohydrates, 97 per cent. These coefficients agree very closely with those found in the average of several hundred digestion experiments with varied diet. In these experiments differences in method of cooking the meat had no appreciable effect upon the proportions of nutrients digested and absorbed from the total diet. In forty-four experiments different kinds of meat — beef, veal, mutton, and pork — cooked in various ways, were eaten wdth two or three other common food materials in a very simple diet, and the digestibility of the meat alone was deterinined. In the average of the results of these experiments the digestibility of the protein was 98 per cent and of the fat 98 per cent. Differences in the results obtained with different kinds of meat or with the same kind of meat cooked in different ways were too small to be of any practical significance. The relative fatness of the meat had no appreciable effect upon the thoroughness of digestion, the nutrients of very fat meat being digested as completely as those of very lean meat, including that from which in some cases part of the visible fat had been removed before cooking. In short, all the kinds and cuts of meat were very thoroughly digested, whatever the method of cooking. 100 The above-mentioned coefficients of digestibility of the nutrients of meat are those derived according to the usual method from the quantity of each in the food and the total quantity in the corre- sponding feces. When allowance was made for the metabolic prod- ucts in the feces, the results obtained indicated that the nutrients of the meat were completely digestible. It is commonly said tliat meats of different sorts vary decidedly in digestibility; for instance, that red meat is less digestible than white meat or beef" than pork, or that a cheap cut is less digestible than a tender steak. As regards the thoroughness of digestion the results of the extended series of tests reported show that such differ- ences do not exist in any appreciable degree, and that meat of all kinds and cuts is to be classed with the very digestible foods. Ninety-nine artificial digestion experiments made for the purpose of testing the relative ease of digestion of different kinds and cuts of meat cooked in different ways do not w^arrant any sweeping deduc- tions. So far as can be judged from the results obtained under the experimental conditions the meat seems to be quite easily digested. About 80 per cent of the meat protein was digested in the first hour and nearly 90 per cent within two hours, Vhatever the kind of meat or the method of cooking, though there were considerable variations from these proportions in the individual experiments. The differ- ences with the several kinds of meat or with meat cooked in a variety of ways are very small or very irregular, and in some cases are ap- parently contradictory, so it can not be said that they indicate any difference that could be attributed to the factors mentioned. o 17 W ,> '- .". •' ,0^ ^ '" • * * aV" Vo "^ ye* ♦' > 'o.,* A <^ ^^7^* ,G^ \3 'o..* j\ <^ ♦TXT* ^0^ .^<^. p"^^ •* "^m*' ^^^"^X °-^^** -^^^^ -^^^ .^^^\. °-^^*\'? ^'^^ -. /4V&% ^^^:^'-% /^i^fi:^'- 4 o . .V « * „ "T*^ ^ > . s • • . ^ f\>* _ » • o *^-v ^ > .*- ■%.„< V ,°^c^-.*< 'A 9^ °o * AT r:^ • iiiiiiiiiiiSiiililiiiiiii^