READJUSTMENTS OF REGULATION 35 



might well retort by asking what regulates all the 

 complex conditions concerned in the process the for- 

 mation and marshalling of haemoglobin and salts in 

 the corpuscles, and the astoundingly delicate balance of 

 the various substances which are concerned in the 

 carriage of CO2. 



Nevertheless the regulation of both the breathing 

 and the carriage of gas by the blood can be disturbed, 

 either temporarily or for long periods ; and it is only 

 by studying these disturbances that we can get further 

 insight into the regulation. It has already been men- 

 tioned that when mineral acids are administered the 

 breathing increases, so that the alveolar CO2 pressure 

 necessarily falls, while the amount of CO2 in the 

 arterial blood may be diminished in acid poisoning 

 to a small fraction of what it normally is. The 

 administration of alkalies has a similar effect in the 

 opposite direction. Slighter effects of a similar kind 

 can be brought about, at least temporarily, by mere 

 changes in diet. In diabetes a condition sometimes 

 occurs in which a great excess of organic acid is 

 formed in the body ; and this also is accompanied by 

 great increase in the breathing and fall in the alveolar 

 CO2 percentage. A temporary effect in the same 

 direction follows exposure to want of oxygen, or 

 excessive muscular exertion. It was known that expo- 

 sure to great want of oxygen leads to the production 

 of lactic acid in the body, and that excessive muscular 

 exertion must have the same effect, since the amount 

 of work done excludes the possibility of the circula- 

 tion being able to supply the muscles with the oxygen 



