Abstract
The ciliary ganglion and its accessories were removed from one orbit in each of a series of cats. At intervals thereafter, the effects on the pupils of a drop of carbaminoylcholine chloride solution in each eye, were studied in the dark-room under conditions of uniform lighting. In the experiments here reported, the dosage in each eye was equivalent to 0.3 mg. of carbaminoylcholine chloride and the eyes, when studied, were 60 cm. from a screen of white muslin, illuminated by a 100 watt mazda lamp, 40 cm. away.
When the irises were tested within 24 days after the operation, the pupils in both the normal and the parasympathectomized eyes were constricted down to the same size, approximately 1 mm. in horizontal diameter. The constriction began within 5 minutes, in both eyes, reached its maximum, in both eyes, at about 45 minutes and, in most cases, remained at this maximum more than 45 minutes.
Since it is probable that the nerve fibers and their endings had completely degenerated before the end of 14 days, and since Armstrong 1 has shown that acetylcholine does not depress the nerveless heart, the foregoing facts suggest that carbaminoylcholine in the given concentration, stimulates only the parasympathetic neuromuscular junctions.
In the later months after the operation, the drug in the normal iris still constricted the pupil down to a 1 mm. width, but in the parasympathectomized iris, it constricted the pupil only to about 8 mm. These findings in the later months are probably due to the degeneration of disuse, either in the denervated parasympathetic neuromuscular junctions or in the muscle fibers.
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