Action of Carbonic Acid 9^7 



Experiment DCXXXVII. June 4. Two feet of the same frog are 

 hung each at the top of a test tube: 

 A in air; 



B in almost pure carbonic acid. 



June 5. A, nerve not excitable; muscle very contractile; 

 B, no muscular contractility. 



6. Summary and Conclusions. 



We have now reached the end of this long study. It is sum- 

 marized in the following propositions: 



A. When an animal breathes in a closed vessel, either in com- 

 pressed air, or in a superoxygenated air, at normal pressure, so that 

 it never lacks oxygen, the increasing tension of C0 2 in the air 

 maintains an increasing proportion of the same gas in the blood, 

 so that the carbonic acid produced within the tissues remains in 

 these tissues. 



B. From this accumulation there results a progressive slacken- 

 ing of the intra-organic oxidations, and consequently, a consider- 

 able lowering of the body temperature. 



C. The central nervous system, in this general effect upon the 

 organism, is the first to show that it is attacked, by the loss of 

 the reflex transmissions, first in the limbs, then in the eye, finally 

 in the respiratory center, from which death results. 



D. No struggle, no convulsive movement precedes death. 



The heart, though slackening its beats, retains its full strength 

 for a very long time, and remains the ultimum moriens (last to die) . 



These two facts definitely disprove the theories which make of 

 carbonic acid either a poison which causes convulsions or a poison 

 of the heart. 



E. The anesthesia produced by carbonic acid apparently de- 

 serves to attract the attention of surgeons again; it is complete at 

 the moment when the life of the animal is far from being in danger. 



F. Plant life, germination, the development of molds, and putre- 

 faction are slowed, suspended, and definitely checked by carbonic 

 acid at a sufficient tension. 



G. Therefore, carbonic acid is a universal poison, which kills 

 animals and plants, large or microscopic; which kills the anatomical 

 elements, isolated or grouped in tissues. And that is not at all 

 surprising because it is the product of universal excretion of all 

 living cells; its presence hinders excretion, and consequently by 

 interposing a terminal obstacle stops the whole series of the con- 

 stituent chemical transformations of life, which begin with the 

 absorption of oxygen and end with the discharge of carbonic acid. 



