716 Experiments 



We have had to use the best physiological reagent, the frog. 



Experiment CCLXIX. February 27. Frog subjected at 2 o'clock to 

 7 atmospheres, 6 of which were oxygen. The oxygen tension corre- 

 sponds to 505. In the evening, at 7 o'clock, nothing particular; seems 

 a little uneasy. 



February 28, at 9 o'clock in the morning, dead. No reflex actions 

 of any sort; the motor nerves and the muscles are excitable. The 

 heart, of a fine carmine red, beats slowly when exposed. Free gases 

 in the blood. 



The lethal air contains no trace of carbonic acid. 



Experiment CCLXX. March 4. Frog subjected at 4 o'clock to 5 

 atmospheres, 4 of which were oxygen; the tension of this gas is about 

 300. 



At 10 o'clock in the evening, swollen. 



On March 5, at 2 o'clock, seems dead. The heart no longer beats 

 spontaneously, but is excitable; the motor nerves and the muscles are 

 excitable. By cutting through the spinal cord in the back, movements 

 in the lower limbs are caused. 



Experiment CCLXXI. February 29. Frog subjected at 6 o'clock 

 to 4 atmospheres, 3 of which were oxygen. 



The tension of this gas is 254. 



The next day, March 1, at 3 o'clock, it is rigid and swollen, seems 

 to have convulsive movements when one raps on the table. At 7 

 o'clock in the evening, is much weaker. 



March 2, at 1 o'clock, dead, stiff. The heart beats, the nerves and 

 the members are excitable; no movement is produced when the spinal 

 cord is cut. 



The lethal air contains no trace of carbonic acid. 



Experiment CCLXXII. April 18. Frog subjected at 6 o'clock in 

 the evening to 4V2 atmospheres of superoxygenated air. The oxygen 

 tension is represented by 335. Temperature 15°. 



The next day, nothing especial in the appearance of the frog. 



April 20, found dead at 1 o'clock. The heart, very pink, is still 

 beating a little. The muscles are perfectly contractile. 



Experiment CCLXXIII. June 17. Frog subjected at 4:30 to a pres- 

 sure of 5 superoxygenated atmospheres. The heart is laid bare, 

 temperature 20°. 



June 18, at 11 o'clock in the morning, very weak, prostrated. No 

 respiratory movements. Pulsations of the ventricles, rare, irregular; 

 but the auricles alone beat 40 times per minute. 



At 3 o'clock, decompression. A few weak heart beats yet. There 

 are no reflex acts, but the motor nerves and the muscles are quite 

 excitable. 



Sugar in the liver, in a rather large quantity. 



We conclude from all these experiments that oxygen does not 

 kill by acting on the heart, the motor nerves, or the muscles. But 



