CHEMICAL PHENOMENA OF RESPIRATION. 331 



tion of oxygen ; this deprivation, however, works by means 

 of another mechanism than that already mentioned ; being 

 simply due to the fact that the blood has lost its power of act- 

 ing as the vehicle of the gas. The carbonic oxide does not 

 exert its poisonous influence directly upon the tissues : Paul 

 Bert has shown that the presence of this gas nas no effect 

 upon the gaseous exchanges constituting the elementary 

 respiration of the tissues, when in contact with the oxygen. 



Some gases act directly on the anatomical elements as 

 poisonous substances ; in such cases asphyxia, properly so- 

 called when speaking of respiration, does not take place, but 

 a poisoning is produced by a gaseous agent : as, for instance, 

 compounds of cyanogen. 



Paul Bert's researches on the subject of the influence of 

 compressed air have led to the discovery of the singular and 

 unlooked-for fact, that if oxygen be sufficiently condensed it 

 becomes poisonous. If an animal (a dog, for instance) be 

 placed in pure oxygen, at an atmospheric pressure of 5 or 6, 

 or, what amounts to the same thing in ordinary air, at a pres- 

 sure of 20 atmospheres, it exhibits the most alarming symp- 

 toms, consisting in attacks of clonic convulsions similar to 

 those produced by strychnine. These effects begin to appear 

 at the moment when the arterial blood of the dog, instead of 

 the normal proportion of 18 to 20 cubic centims. of oxygen 

 to 100 cubic centims., contains only from 28 to 30. If the 

 proportion reaches 35 cubic centims., death usually follows. 

 It is remarkable that the convulsive movements continue 

 after the animal has been placed again in the fresh air, and 

 after the blood has been restored to its normal condition. 

 This seems to show that, under the influence of this remark- 

 able hyper-oxidation of the hemoglobuline, a poisonous prod- 

 uct is formed in the blood, the effects of which resemble 

 those produced by strychnine or carbolic acid. 1 



E. General results of respiration. 



The gaseous interchange in the lungs is thus only the 

 result of the products of the partial respiration (combustion) 

 which takes place in the different departments of the organ- 

 ism : since to breathe is to live and to perform the functions 

 of life, the measure of the life and energy of the working of the 

 organism in general will give the amount of the pulmonary 

 gaseous exchanges. Under different circumstances consider- 



1 Paul Bert, " Comptes-rendus de 1'Academie des Sciences." 

 1872-73. 



