NUTRITION LABORATORY. 221 



METABOLISM IN DIABEITES MELLITUS. 



Although most of the year was occupied in the computations of earlier 

 researches in this line, opportunity was had to study one particularly inter- 

 esting case of diabetes, and a most careful series of experiments was made 

 on this subject. The results are incorporated in a report on diabetes mellitus, 

 Publication No. 176 of the Carnegie Institution of Washington. 



COMPARISON OF METHODS FOR DETERMINATION OF THE RESPIRATORY 



EXCHANGE. 



This research, which was begun by Mr. T. M. Carpenter, of the laboratory 

 staff, has been prosecuted during the spring and summer months. In con- 

 nection with this investigation comparisons were made of the following 

 apparatus : 



(i) The bed calorimeter, with the Benedict respiration apparatus devel- 

 oped in this laboratory. This portion of the comparison has extended over 

 several years, and a large number of experiments have been made, the two 

 apparatus being used on the same day so as to secure results more strictly 

 comparable. In this comparison both the older and later types of respira- 

 tion apparatus were used. 



(2) The older form of the Benedict respiration apparatus, employing a 

 rubber diaphragm, with the later type in which a spirometer is used. The 

 experiments were made with subjects without breakfast, i. e., after at least 

 12 hours' fast, these being alternated in a series, or a series of experiments 

 carried out with one apparatus, and a subsequent series made on the other. 

 A comparison of nose and mouth breathing has also been made with this 

 apparatus, using both the earlier and later forms. 



(3) The Zuntz apparatus and the Benedict respiration apparatus. In 

 some experiments with the former, the Zuntz gas-analysis apparatus was 

 used, and in others the Haldane gas-analysis apparatus. In connection with 

 this comparison, collection of the gas samples was made both over water and 

 over mercury. Various types of valves, also the nosepiece and the mouth- 

 piece, were used. 



(4) The Tissot apparatus with the Benedict respiration apparatus. In 

 this comparison the Tissot spirometer, Chauveau valves, and the glass nose- 

 pieces were used, both the nosepiece and mouthpiece being employed. 



(5) The Douglas method of determining the respiratory exchange was 

 also tested, two sizes of bags being used for the collection of gas, different 

 types of valves, and both the mouthpiece and the nosepiece. 



For studying the ventilation of the lungs with different types of valves, a 

 specially constructed spirometer was used; from this study has resulted a 

 respiration apparatus of the closed-circuit type, using a spirometer and 

 valves, with calcium chloride as the absorbent of water. 



15— YB 



