RESULTS.

Considering the relatively large quantity of ammonia injected into the blood the analyses indicate a very rapid disappearance of the excess from the blood in both normal and thyroidectomized animals. The average ammonia content of blood of seven normal cats was 0.6 mgm. per 100 cc. as against 0.9 mgm. five minutes after the injection of 50 mgm. per kilo body weight. There was noted, also, considerable individual variations in the amounts which remained after five minutes. In the thyroidectomized animals the ammonia content averaged 0.85 mgm. per 100 cc. of blood, with 1.31 mgm. five minutes after the injections. There seems to be a slightly greater ammonia content in the blood of the thyroidectomized animals, and a slight decrease in the rate of disappearance of the ammonia from the blood. The differences, however, are so small as to be of doubtful significance.

The third series of experiments (Table III) gives an indication of the amount of ammonia that disappears from the blood by diffusion into tissue spaces, lymph, and cells outside the gastrointestinal tract. These animals showed an increase in susceptibility to the ammonia injections not a few having marked symptoms. The analyses show a much greater excess of ammonia than in the previous series I and II.

In view of the fact that these animals received 100 or more mgm. of ammonia per 100 cc. of blood intravenously, the presence of as little as 3 to 9 mgm. per 100 cc. of blood five minutes after the injection means that nearly all the ammonia passes out of the blood quite apart from any action of the kidneys, the liver, or the digestive tract. The larger excess remaining in the last series of experiments may be due mainly to the exclusion of so much tissue (the liver, stomach, and intestines) from the circulation rather than a depression of the ammonia-destroying function of the liver.

SUMMARY.

1. Even with the kidneys excluded from the circulation, ammonia injected into the blood is so rapidly removed from the blood that only a very slight excess is present five minutes after the injection.

2. There is only a very slight difference between the normal and parathyroidectomized animal in the rate of disappearance of the ammonia from the blood.

3. The method employed is not adequate for the determination of liver efficiency (ammonia-destroying power), because the rate of disappearance of excess of ammonia from the blood independent of the liver function is so great as to render the actual ammonia destruction by the liver almost a negligible factor.

THE BASAL, GASEOUS METABOLISM OF NORMAL MEN

AND WOMEN.1

BY FRANCIS G. BENEDICT, LOUIS E. EMMES, PAUL ROTH,
AND H. MONMOUTH SMITH.

(From the Nutrition Laboratory of the Carnegie Institution of
Washington, Boston, Mass.)

(Received for publication, May 9, 1914.)

The impetus given to the study of gaseous and gross metabolism during the past decade has resulted in a large number of observations, both in the domain of physiology and pathology. Investigators in pathology are, however, continually confronted by the paucity of normal data with which to compare their observations. Benedict and Joslin,2 stimulated by the arrival in Boston of Dr. Falta of Vienna, began immediately studying the metabolism of diabetics with the new respiration calorimeters in the Nutrition Laboratory. Before their investigation was completed the need for normal data for control was imperative. Though they recognized the importance of normals and published in their first publication on diabetics a number of normals for comparison, Lusk3 pointed out the deficiency in the number of normals that they

The larger number of observations reported here were made in the Nutrition Laboratory, chiefly by Emmes, but in part by T. M. Carpenter and H. L. Higgins, in connection with other researches. We wish here to acknowledge our obligation to Messrs. Carpenter and Higgins.

Certain of the experiments were made on vegetarians by Roth at Battle Creek, Michigan, in the Battle Creek Sanitarium. Our thanks are due to Dr. J. H. Kellogg for providing the respiration apparatus and the subjects for the experiments on vegetarians.

The experiments on athletes were carried out by Smith, in the Chemical Laboratory of Syracuse University, Syracuse, New York.

In the tabular classification of the experiments the name of the experimenter will accompany each observation.

2 Benedict and Joslin: Metabolism in Diabetes Mellitus, Carnegie Institution of Washington, Publication No. 136, 1910.

Lusk: Science, xxxiii, p. 433, 1911.

reported, and hence in their second diabetic publication' they enlarged the list of normal individuals for comparison purposes.

More recently a visit by two of us to the Respiration Calorimeter Laboratory in Bellevue Hospital, New York City, brought out the fact that Drs. Coleman and DuBois were making an extensive and fundamental study of metabolism during typhoid fever, using an extremely accurate bed calorimeter, and we were there again impressed with the fact that there was a great deficiency of knowledge of the metabolism of normal individuals available for the purposes of comparison. With infants, Benedict and Talbots have experienced a similar difficulty. However, within the last year or two the increased use of the respiration calorimeter of the type developed at Wesleyan University and in this Laboratory, and of the universal respiration apparatus has made possible the accumulation of a considerable number of normal as well as pathological values.

Since by far the larger amount of work on normal individuals has been carried out in a coördinate series of experiments in connection with this laboratory and others which we represent, it has been felt desirable to prepare immediately a summary of the results on normal individuals obtained with these forms of apparatus up to the present date.

In dealing with normal men difficulties are always experienced when the conception of the word "normal." As popularly understood "normal" would mean "average," but in dealing with metabolism observations we may draw a somewhat sharper line and say average values obtained from people in presumably good health." It has been clearly shown that gaseous metabolism is profoundly affected by a number of factors-muscular activity and fever being most pronounced in their effects. By selecting persons of normal temperature, or at least of non-febrile temperature, during periods of muscular repose these two factors may be eliminated. But with every individual there are periodicities in the rate of metabolism during the day, incidental to the ingestion

4 Benedict and Joslin: A Study of Metabolism in Severe Diabetes, Carnegie Institution of Washington, Publication No. 176, 1912.

Benedict and Talbot: The Gaseous Metabolism of Infants, with Special Reference to its Relation to Pulse-rate and Muscular Activity, Carnegie Institution of Washington, Publication No. 201, 1914.