1022 Summary and Conclusions 



this agent; putrefaction is stopped," and the consumption of oxygen 

 which accompanies it lessens so much that it can be reduced to 

 zero. Now the anatomical elements, in the presence of excessive 

 oxygen, behave like free elementary beings, and when they die, 

 cease to consume the oxygen necessary for the maintenance of 

 their vital acts. 



Let us follow this a little further. And first, we have seen for 

 plants as for animals that the pressure of 5 or 6 atmospheres of 

 air (oxygen tension 100 to 120) brings symptoms serious enough 

 for laboratory experiments, which are carried on in a short space 

 of time, to indicate them very clearly. So respiration of pure 

 oxygen at normal pressure (tension 100) cannot be long endured 

 by warm-blooded animals. At about 10 or 12 atmospheres symp- 

 toms appear that are quickly fatal, and at about 20 atmospheres, 

 the characteristic convulsions of oxygen poisoning. Now at 6 

 atmospheres the oxygen of the arterial blood has increased by 

 only 3 volumes; at 12 atmospheres, it has passed on the average 

 from 20 to 25 volumes; at 20 atmospheres, from 20 to 29 (See Fig. 

 36) ; when it passes from 20 to 35 (example: Experiment 

 CCLXXXVII, 27 atmospheres) death occurs in a few minutes. On 

 the other hand, we have several times stressed this fact, that the 

 arterial blood, in the normal acts of respiration, is almost never 

 saturated with oxygen. When the trachea is opened and there 

 follows, as often happens, a much exaggerated respiration, or when 

 blood is agitated in a flask of air, it gains 3 or 4 volumes on the 

 average. 



So the pressure of about 6 atmospheres of air results in intro- 

 ducing into the arterial blood almost the quantity of oxygen which 

 would be necessary to saturate it under normal pressure. And, we 

 have seen, this pressure begins to be harmful to higher organisms. 

 The saturation of the blood would, then, be a harmful condition, and 

 by a happy arrangement, when it is reached, the apnea which 

 ensues prevents it at once from persisting. 



From this degree of pressure on, the hemoglobin is saturated 

 with oxygen, and the oxygen which is added to the blood follow- 

 ing a progression which approaches Dalton's Law, is only dissolved 

 oxygen, equally divided between the corpuscles and the plasma; 

 and it even dissolves also in the tissues to the same degree, if the 

 stay in compressed air lasts a sufficient time. Now it is a fact of 

 the highest interest that in the presence of this free oxygen that 

 is simply dissolved, the inner oxidations slow up, then stop. It 

 seems that for oxidation the tissues need borrowed oxygen, taken 



