DIVEESE COMPONENTS 345 



gen is breathed instead of air, or oxygen gas is injected, certainly 

 are quickly lost by utilization almost in situ. 



Tolerance curves for rate of oxygen intake, and recovery of 

 rate of oxygen intake, are quantitatively represented in many data : 

 e.g., Margaria et al. ('33, '34), Hansen ('34), Herxheimer ('35), 

 Iljin-Kakujeff ( '36, see fig. 176 below), and Szwejkowska ( '38). 



It may be noted that in the present investigation, the terms 

 deficit and debt are used interchangeably. Whether the deficit as 

 computed from the oxygen intake during acceleration subtracted 

 from the oxygen intake after acceleration has ceased, is the same as 

 the deficit (debt) as computed from the oxygen intake during 

 deceleration minus the oxygen intake after deceleration, is of no con- 

 sequence in the relations here discussed. That question becomes of 

 consequence when someone is concerned whether chemical combus- 

 tions are permanently suppressed when the body economizes under 

 scarcity of oxygen. 



If some other correlative of oxygen content is substituted for it, 

 as arterial oxygen concentration, or inspired air tension of oxygen, 

 the oxygen intakes also may be correlated with steady states of 

 deficit. Thus, for instance, a relation is established between ventila- 

 tion rate and oxygen load; this correlation is of interest in that 

 ventilation rates increase much only in those oxygen tensions less 

 than half of the usual ones in atmospheric air. 



Comparison of figures 171 and 172 indicates the partially 

 reciprocal relations of carbon dioxide and oxygen. The same 

 breathing that brings oxygen into the lungs also bails out carbon 

 dioxide. But more oxygen in the lungs does not add significantly 

 to the oxygen content of the body as a whole. For carbon dioxide, 

 on the other hand, the ventilation of the lungs itself looks almost 

 like a limiting process to its content. Oxygen and carbon dioxide 

 are each able to arouse more alveolar ventilation, but only in ranges 

 of tensions or contents that usually do not occur together. Further, 

 heat excesses, increased breathing (panting) modifies but little the 

 content of either. Adjustments of oxygen load are prevented from 

 interfering with adjustments of carbon dioxide content by the 

 agency of hemoglobin in blood, and panting is harmless as long as 

 it refills dead space. There was a time when no one predicted either 

 that excess oxygen would arouse no response of breathing or that 

 carbon dioxide deficit would be compensated. The relative influ- 

 ence upon alveolar ventilation of equal increments of tension in 



