RESPIRATION 



159 



ing vessel filled with pure carbon monoxide, so arranged that the 

 gas was driven into the vessel containing the mouse. The animal 

 was now in a mixture consisting of two parts of oxygen and one 

 of carbon monoxide, at a total pressure of two atmospheres of 

 oxygen and one of carbon monoxide. It could also be killed by 

 drowning in this atmosphere if water was forced over. 



My calculation was that in the presence of two atmospheres of 

 oxygen the animal would have in simple solution sufficient oxy- 

 gen in its arterial blood to supply the oxygen requirements of its 

 tissues, at any rate during rest; and that it would thus be inde- 

 pendent of the oxygen supply shut off through the action of the 



Figure 51. 

 Apparatus for exposing mouse to atmosphere of oxygen and CO. 



CO, with which the haemoglobin would be almost completely 

 saturated. If, however, the CO had any toxic action apart from 

 its action in producing anoxaemia this action would certainly 

 manifest itself at once, since the partial pressure of the CO was 

 100 per cent of an atmosphere, whereas in CO poisoning as ordi- 

 narily met with in non-fatal cases, the partial pressure of CO 



