An examination of the summary of values given for the calorimeter experiments in table 67 (see page 135) shows that there was but little or no increase in the heat output in these experiments. The maximum increment was that on May 9,1907, of 4 per cent. Furthermore, the figures show no variation as a result of the differences in the temperature of the beef tea, nor is there an apparent correlation between the total nitrogen content of the beef tea and the heat increment.

The beef tea for the respiration experiments, the results of which are summarized in table 68, was made from beef extract in all cases except for the experiment with C. H. H. on February 8, 1911. In practically every experiment there was a perceptible increase in the metabolism, the maximum being that in the experiment with J. J. C, on January 25, 1911, namely, 12 per cent. The average increment was not far from 8 per cent, a result strikingly at variance with that found in the calorimeter experiments. This is all the more significant as comparatively small amounts were given in the respiration experiments (never more than 400 grams), while in the calorimeter experiments, if we exclude that with J. R., the amount ingested ranged from 892 grams to 2,056 grams. As further evidence of the positive increase noted in the respiration experiments, an examination of the detailed results given in tables 95 to 100 shows that the increment in the oxygen consumption was usually still present at the end of the experiment, i. e., the metabolism had not reached the basal level. The values for the total increment here recorded are therefore for the most part smaller than would have been obtained had the experiment been continued.

The most striking result obtained in these experiments is the very small reaction to the beef tea shown by the subject C. H. H., this being much less than in any of the other respiration experiments in the series. This man was a particularly satisfactory subject with the respiration apparatus, as he lay without movement for hours at a time and showed an unusually clear understanding of the requirements of a cooperating subject. The high values obtained with J. J. C. and V. G. can probably be ascribed to their tendency towards restlessness and lack of cooperation. In any event the results of these respiration experiments appear to show that beef tea, when prepared from the so-called commercial extract of beef, has an influence on the metabolism. This effect in certain of the experiments was fairly long continued and amounted at times to an increase of heat approximately 8 to 10 per cent above the basal value.

The pulse rate was affected to a slight extent in the calorimeter experiments in Boston. Only two of the experiments with the respiration apparatus show significant increases in pulse rate, these being the experiment with C. H. H.? February 8, 1911, in which the rate rose from 65 per minute to a maximum of 71, and the experiment with V. G., January 26, 1911, in which the pulse rate changed from an average of 53 per minute to 67 to 60 per minute after the beef extract was taken.

The systolic blood pressure was measured in the experiment with V. G., February 3, 1911, and in the three experiments with C. H. H. In none of them was there a marked change in the blood pressure.

While beef extract has an effect upon the metabolism, its influence is so small that moderate amounts may be given to individuals in a fasting condition without materially increasing the basal value. Since it is highly desirable to secure a diet which will not materially raise the basal metabolism and yet will prevent the sensations of hunger frequently experienced by patients when the breakfast is omitted, it may be perfectly legitimate to use a moderate amount of beef extract in experiments with pathological cases even when determining the so-called basal value prior to observations. Special tests on this point should be made before beef extract is used in this way.

In considering the influence of beef tea and other liquids upon the metabolism, the results obtained in the experiments on water-drinking should naturally be taken into consideration. A careful analysis of these experiments shows that the drinking of water was, in all but two instances, without effect upon the metabolism. On the other hand, the fact that increments were obtained in these two experiments, one of which - an extremely well-conducted and satisfactory experiment - showed an increment of 16 per cent in the metabolism after 1,800 grams of water,1 must lead one to be somewhat cautious in the interpretation of results of experiments in which liquids are ingested. But the experimental data thus far obtained for beef tea may properly lead to the conclusion that with amounts of 400 grams or more a perceptible increase in the metabolism may be expected.

1See experiment with T. M. C. on January 12, 1911 (table 72, p. 144).