Increased Pressure 1023 



from the oxy-hemoglobin, so that in the presence of dissolved 

 oxygen brought by compression, either the tissues become unable 

 to carry out this dissociation, or the corpuscles can no longer give 

 up their oxygen, and remain condemned to perpetual saturation. 

 I know nothing in physiological chemistry more curious than this 

 effect of the presence of dissolved oxygen, having as its result not 

 the activation but the checking of a combination. Whatever are 

 the possible explanations, it is certain that the organic oxidations 

 no longer take place when the blood corpuscle, laden nevertheless 

 with the maximum of oxygen, is surrounded by this sort of at- 

 mosphere of free oxygen, dissolved in the plasma, dissolved in the 

 tissues. 



We have seen, I remind you again, that this cessation of the 

 oxidizing activity of the tissues takes place in the presence of an 

 excess of oxygen, not only in red-blooded animals, but in all living 

 beings. Now this cessation of vital phenomena is not merely 

 momentary, like that caused in lower beings by the diminution 

 of pressure, but is a real death, a definite death; which shows that 

 very evidently we have to do here not with a simple suspension but 

 with a deviation of the vital phenomena. A seed kept in a vacuum 

 germinates when oxygen is admitted; a dog with the convulsions 

 of asphyxia is restored when given air. But the seed kept under 

 compression will no longer germinate; the dog brought from com- 

 pressed oxygen to normal pressure may, after twenty-four hours 

 of continuous convulsions, die without having improved. (Experi- 

 ment CCLXXVIII.) It seems that under the influence of com- 

 pressed oxygen there is formed in the anatomical elements some 

 toxic product which cannot always be eliminated, and then kills 

 even when its cause has disappeared. To go further than this 

 hypothesis would seem to be imprudent in the present state of 

 knowledge. 



The researches of M. Pasteur have shown that microscopic liv- 

 ing beings can be divided into groups, one needing for life contact 

 with the air, free oxygen (aerobic) , the other (anaerobic) fearing 

 air, on the contrary, and borrowing the oxygen which they consume 

 from organic materials which they separate for this purpose. Now 

 what we have just said shows that anatomical elements grouped in 

 tissues are essentially anaerobic. In the upper animals, where it 

 has been possible to carry the analysis of phenomena to great 

 lengths, we know that they secure their oxygen from the oxy- 

 hemoglobin; but when the latter is saturated, the oxygen appears 

 simply dissolved in the plasma and the tissues, the animals become 



