INTRODUCTION. 7 



the relationship between the severity of diabetes and the degree of increased 

 metabolism; and third, the influence of a carbohydrate-free diet upon the total 

 metabolism of normal individuals. Incidentally the accumulated data jus- 

 tify the discussion of the factors affecting body-weight. In connection with 

 the research a modified method for the rapid quantitative determination of 

 sugar in the urine has been elaborated which is described at some length. 



Apparatus and Methods. 



The apparatus and methods used in the conduct of this research are essen- 

 tially those described in the earlier publication. 1 The bed calorimeter has 

 been more extensively employed than has the chair calorimeter, the latter 

 being used for only three experiments in this connection. On the other hand, 

 the respiration apparatus, which has continually undergone minor modifica- 

 tions in methods of technique and facility of operation, though not in principle, 

 has been extensively used. 2 In most instances it has been found that observa- 

 tions made with this apparatus are fully as valuable and essentially the same 

 as are the more time-consuming and expensive observations with the respi- 

 ration calorimeter; hence we have no doubt of the wisdom or propriety of com- 

 puting the energy transformations from the gaseous metabolism as determined 

 on the respiration apparatus. The respiration apparatus has the special 

 advantage in that with it experiments can be made rapidly, and thus the time 

 relations of the metabolism, particularly after the ingestion of food, can be 

 more exactly and rapidly studied than in experiments with the respiration 

 calorimeter, with the longer periods of 45 minutes. 



DETERMINATION OF GASEOUS TENSIONS OF ALVEOLAR AIR. 



Owing to the interesting observations of Beddard, Pembrey and Spriggs, 3 

 it seemed advisable in certain instances to determine the composition of the 

 alveolar air in severe cases of diabetes. Accordingly, with three subjects 

 (I, N, and Q) observations were made of the carbon-dioxide tension, and at 

 times the oxygen tension, of the alveolar air, these being in large part carried 

 out through the kindness of Mr. H. L. Higgins, of the laboratory staff, who 

 used the Haldane gas-analysis apparatus 4 and both the Haldane and the Plesch 

 methods for determining the alveolar air. 5 



VENTILATION OF THE LUNGS. 



Using an Elster meter of the type employed by Zuntz, and a pair of Zuntz 

 valves, the ventilation of the lungs per minute was also occasionally deter- 

 mined with one of the subjects (N). 



Benedict and Joslin, loc. tit., p. 15. 



2 A detailed description of the apparatus, showing its use and technique, has just been 

 published in the Deutsch. Archiv. f. klin. Med., 1912, 107, p. 156. 



3 Beddard, Pembrey and Spriggs, Proc. Physiol. Soc, Journ. Physiol., 1908, 37, p. 39. 



4 Haldane, Methods of air analysis, London, 1912. 



6 Haldane and Priestley, Journ. Physiol., 1905, 32, p. 225; Plesch, Zeitschr. f. Exp. 

 Pathol, u. Ther. 1909, 6, p. 380. 



