The Contents of Acetylcholine and Choline Esterase in the Electric Organ of Narke japonica (Temminck and Schlegel).

1) The total amount of ACh yielded from the electric organ was enormously high, and estimated to 8.5 - 15.0γ (average 12.0γ) per gramm of the tissue weight. There was no difference in the content of ACh between the stimulated and non-stimulated organs. 2) The total amount of ACh of the central nervous system and skeletal muscle of the electric ray was 4.4-5.2γ and 0.0- 1.1γ per gramm of the tissue weight respectively. ACh has not been proved from the intermediate muscle. 3) The activity of Ch E was enormously high in the electric organ ; it diminished gradually from the central nervous system, then from the skeletal muscle, and lastly from the intermediate muscle. If the enzyme activity of the electric organ is taken as unity, then that of the central nervous system, skeletal muscle and intermediate muscle corresponds to 0.026, 0.018 and some thousandth times of that of the electric organ respectively. 4) The enzyme activity of the central nervous system and skeletal muscle of the gold fish corresponds to 0.07 and 0.017 of that of the electric organ respectively. 5) There was a close parallelism between the content of ACh and the activity of Ch E in some tissues of the electric ray.