MECHANICS OF KESPIRATION. 479 



dioxide output, one can, assujning a dead space, also compute the 

 carbon-dioxide tension in the alveolar air. In addition to these data 

 we determined directly in a large number of cases the alveolar carbon- 

 dioxide tension by a special technique. (See p. 79.) All of these 

 values are recorded, together with certain other respiratory figures, 

 in table 111. 



The data for the total ventilation of the lungs per minute are re- 

 corded in the first two columns of the table, the first column giving 

 the ventilation as actually observed from readings of the spirometer, 

 and the second, the same data reduced to 0° C. and 760 mm. pressure. 



The actual number of observations made of the total ventilation of 

 the lungs prior to the reduction in diet are very few, only Can and Gar 

 showing more than one value. The data for October 5 or subsequent 

 thereto were obtained after the reduction in diet began. An inspection 

 of the figures in both columns a and b shows a distinct tendency for the 

 total ventilation of the lungs, both observed and reduced, to decrease 

 somewhat with the length of time, although not necessarily in direct 

 proportion to it. As a matter of fact, for the most part high values 

 were found only in the first three observations, and but occasionally 

 thereafter. In nearly every case after the first two weeks in October, 

 a high ventilation of the lungs was accompanied by a large oxygen 

 consumption. For example, with Gar, after a long series of values for 

 ventilation per minute of 4.5 liters or under (see second column), we 

 find on January 10, 14, and 18 three high values of practically 5 liters 

 or over. These were all accompanied by a distinct increase in the 

 oxygen consumption. The total metabolism is thus actually increased 

 and there is an increased ventilation of the lungs to bring away the 

 excess formation of the carbon dioxide. In general, there is a clear 

 tendency for a decrease in the total ventilation of the lungs with a 

 reduction in diet. 



VOLUME PER RESPIRATION. 



As stated in the preceding section, the respiration rate per minute 

 showed a tendency to decrease; the volume per respiration has there- 

 fore an interest. These volumes are recorded in the last column of 

 table 111. Although these volumes show in a number of instances 

 a slight tendency to decrease, they do not on the whole indicate a 

 profound effect of the low diet. Certain cases, particularly Vea and 

 Gul, show a tendency towards a pronounced reduction in volume 

 per respiration. As a matter of fact, the values for Gul range from 

 634 c.c. on October 1 and 20 to as low as 399 c.c. on January 21, this 

 being by far the widest difference noted with any of the subjects. Vea 

 shows a range from 496 c.c. on October 8 to 381 c.c. on November 5. 



In general, however, the slight decrease in the respiration rate 

 which was noted as the research progressed, accompanied by a similar 



