In considering the outcome of our experiments, it may be wise to enter into some detail concerning the first case to be presented. The animal employed in this experiment was designated as No. 5, and weighed on July 27,1905,17.2 kilograms; it was apparently full grown, but was thin and had the appearance of being underfed. At first, it was given daily 172 grams of meat, 124 grams of cracker dust, and 72 grams of lard, the day's ration containing 8.66 grams of nitrogen and having a fuel value of 1389 calories.1 These figures are equivalent to 80 calories, and 0.50 gram of nitrogen, per kilogram of body-weight. The animal took kindly to the diet, but on August 3 it refused to eat and seemed to have a little fever. The next day it was better, but for the three following days its appetite was poor, and only a portion of the daily food was eaten. Body-weight began to fall off, and was soon at 15.5 kilograms. On the 7th of August, a dose of vermifuge was given, after which the appetite returned and the animal appeared in good spirits. From this time forward it seemed in perfect health, with good appetite, and showed the usual vivacity and playfulness of dog-kind. The diet as specified was continued unchanged until August 25, a balance experiment covering a period of ten days, from the 15th to the 24th of August inclusive, being carried out, in which the nitrogen of the intake was compared with the output for each day. From the accompanying table, where are given the average values of all the balance periods of the experiment, it is to be seen that during this first period the animal was laying on or gaining an average of 2 grams of nitrogen per day.

1 The fuel value of the food was calculated from the data given in Bulletin No. 28, U. S. Department of Agriculture. All figures for nitrogen were obtained by exact chemical analysis.

Subject No. 5. Daily Averages

1 All through the balance periods the dogs were catheteriaed each morning to insure complete collection of the twenty-four hours' urine.

On August 25, a radical change was made in the diet, by reducing the amount of meat to 70 grams daily, thereby lowering the intake of nitrogen to 4.76 grams, or 0.27 gram per kilo of body-weight; the cracker duet and lard being kept at essentially the same levels as before. This diet was continued through the next balance period, the dog in the meantime gaining in body-weight, and showing for the second balance period an average gain by the body of half a gram of nitrogen per day. The food was then altered by substituting bread for the cracker dust, but so adjusted that the nitrogen and fuel values of the day's food remained practically unchanged. There was still, however, a gain in body-weight and a slight gain in body nitrogen. At the close of the third balance period, the diet was again altered, one-half of the meat being replaced by milk, while cracker dust was sulsti-tuted for the bread. The morning meal consisted of 170 grams of milt, 86 grams of cracker dust, and 18 grams of lard, while the afternoon meal was composed of 35 grams of meat, 63 grams of cracker, and 35 grams of lard. The day's ration, however, still contained 4.76 grams of nitrogen and had a fuel value of 1249 calories. This diet was maintained until November 20, when the animal was again placed on a daily ration of meat (69 grams), bread (166) grams, and lard (80 grams), with a total fuel value of 1228 calories and 4.77 grams of nitrogen. This was continued until December 2, the dog still showing a plus nitrogen balance, but with a little loss in body-weight. On December 2, the diet was again changed by substituting milk for a portion of the meat, but the nitrogen and fuel values were maintained at the same level as before. After a week, December 9, the food was modified as follows: the morning meal contained 170 grams of milk, 110 grams of rice, amd 11 grams of lard, while the afternoon meal was composed of 35 grams of meat, 81 grams of rice, and 30 grams of lard. The total nitrogen content of the day's ration was 4.07 grams, while the fuel value was 1255 calories. At this time, the animal weighed 17.1 kilograms, consequently the intake of nitrogen had been reduced to 0.23 gram per kilo of body-weight, while the fuel value stood at 73 calories per kilogram. This diet was continued until February 9, the balance period, between January 2 and 11, showing that the animal was in nitrogen equilibrium, in spite of the material reduction in the intake of proteid, and that body-weight was increasing. The next balance period, January 30 to February 8, showed still further gain in weight with continuance of nitrogen equilibrium. On February 9, the diet was changed by returning to 70 grams of meat, 158 grams of cracker dust, and 60 grams of lard, with a daily intake of 0.28 gram of nitrogen per kilo of body-weight.

Subject No. 5 August 19, 1905.

Subjtet No. 5. November 18, 1995.

Subject No. 5. April 24, 1906.

Subject No. 5- June27. 1906.

In this manner, the experiment was continued with frequent changes in the character of the diet, but always maintaining essentially the same values in nitrogen and calories as shown in the table, until June 27; having ex tended through just eleven months, with the animal at the close of the experiment still gaining in body-weight) with a steady plus balance of nitrogen, and with every indication of good health and strength. For ten months the animal lived with perfect comfort and in good condition on an average daily intake of 0.26 gram of nitrogen per kilogram of body-weight, and with an average fuel value of 70.3 calories per kilo. Further, it is to be observed that at no time during the ten months did the daily intake of nitrogen rise above 0.28 gram per kilo, while during one month it fell to 0.23 gram per kilo. Similarly, the fuel value of the daily food never exceeded 73 calories per kilo, while at times it dropped as low as 67 and 65 calories per kilo. That this diet was more than sufficient, both in nitrogen and fuel value, is indicated by the steady increase in body-weight and by the plus nitrogen balances observed in most of the periods throughout the experiment. Indeed, with the comparatively low degree of muscular activity which this animal was accustomed to, it would have been unwise to have kept the subject much longer on a diet so rich as the above, since there would have been danger of detriment to its health and good condition. When these results are contrasted with the statements of Munk and Rosenheim, the latter of whom found that even 0.32 gram of nitrogen and 110 calories per kilo were insufficient to maintain dogs in a condition of health, it is plain that for some reason our results are quite at variance with their findings.

The accompanying photographs, taken on August 19,1905, February 27, April 24, and at the close of the experiment on June 27, 1906, show the appearance of the animal at the respective dates, and indicate more clearly than words can express the actual condition of the animal.