Acetylcholine in adrenergic terminals of the cat iris

1. Acetylcholine was bio‐assayed in the normal cat iris, and also after selective sympathetic or parasympathetic denervation. Sympathetic denervation caused no significant change in the acetylcholine content of the cat iris, whereas selective parasympathetic denervation reduced the acetylcholine content below the level of detectability, which on the average was at about 5% of the acetylcholine content of the normal iris.