THE PROCESSES OF DEPRESSION 249 



for this purpose by Baglioni} Two frogs under uniform condi- 

 tions of temperature were submitted to artificial circulation, the 

 one merely with an oxygen-free fluid, the other with the same, 

 but with the addition of 5 per cent, of alcohol. In order to render 

 the least trace of irritability perceptible, responsivity was in- 

 creased in both animals by the employment of strychnine. It 

 then appeared that, on the average, irritability was obliterated in 

 the narcotized frog in about the same time as in the animal 

 simply asphyxiated. These experiments were controlled by intro- 

 ducing at their conclusion a saline solution containing oxygen 

 into both frogs and by ascertaining the degree of recovery. In 

 like manner Frohlich^ has established the same fact for the nerve. 

 The period of asphyxiation for the nerve in a nitrogen-ether 

 mixture is approximately the same as in pure nitrogen. Analo- 

 gous experiments have been carried out in amoebae bj Ishikawa.^ 

 Here also it has been shown that living substance becomes 

 asphyxiated in narcosis and can finally recover only when oxygen 

 is supplied. In more than a hundred experiments Ishikawa has, 

 however, obtained the uniform result that amoebae asphyxiate 

 rather sooner in narcosis than in pure nitrogen. The most strik- 

 ing experiments are those which Heaton* has carried out on the 

 nerve. Using both sciatic nerves of the same frog, he passed 

 each one through a separate glass chamber, as previously de- 

 scribed, and laid the central stumps projecting from the chamber 

 over a pair of platinum electrodes, while the stretch within was 

 likewise placed on platinum electrodes. The muscles served as 

 indicator of the capability of conduction and irritability. The 

 alterations thereof were tested by the ascertainment of the 

 threshold of stimulation. The nerve in the one chamber was 

 then subjected to a pure nitrogen current, that in the other merely 

 to one of pure air with ether. In order to test the degree of 



1 Baglioni: "Bezichungenzwishen physiologischer Wirkung und chemischer Consti- 

 tution." Zeitschr. f. allgem. Physiologie Bd. Ill, 1904. 



2 Fr. W. Frohlich: "Zur Kenntniss der Narkose des Nerven." Zeitschr. f. allgem, 

 Physiologie Bd. Ill, 1904. 



3 The experiments of Ishikawa have not as yet been published. 



4 Trevors B. Heaton : "Zur Kenntniss der Narkose." Zeitschr. f . allgem. Physiol- 

 ogie Bd. X, 1910. 



