RESPIRATION 215 



difficulty in respiration is due to a breakdown in the 

 circulation and a failure of the regular transportation 

 of oxygen between the lungs and the tissues. 



The carbonic acid in the blood is distributed equally 

 through the corpuscles and plasma. It is to a small 

 extent in solution, but for the most part combined with 

 alkali in the plasma and corpuscles, and perhaps also to 

 some extent united in some fashion to the haemoglobin. 

 It is the alkalinity of the blood which gives it its chief 

 power as a C0 2 carrier, for sodium carbonate (Na 2 C0 3 ) is 

 able to take up one molecule of the gas, forming sodium 

 bicarbonate (NaHC0 3 ). There seems to be a constant 

 struggle going on between the proteins of the blood and 

 C0 2 for the possession of the sodium carbonate of the 

 plasma, and it depends upon the relative mass of each 

 present which prevails. Should any stronger acid get 

 access to the circulation and lay hold of the existing 

 alkali, the carriage of C0 2 is greatly interfered with. 

 Until recently it was believed that this took place in 

 diabetic coma owing to the presence in the blood of 

 large quantities of oxybutyric acid ; but the observations 

 of Pembrey have rendered it doubtful whether the 

 sodium carbonate is sufficiently neutralized in that 

 condition to interfere seriously with the transport of 

 C0 2 from the tissues. 



On the subject of ventilation a study of the chemistry 

 of respiration throws disappointingly little light. We 

 do not even know, to begin with, what the effects of 

 ' fresh ' air are due to, or wherein the evils of ' vitiated ' 

 air consist. Analysis has failed to tell us to what 

 ingredients the different effects on health and vitality 



