What is a white crystalline substance of a sweetish taste, resembling inosite and metameric with dextrose. It is extracted from the kidney of the dogfish (of the genus Scylium), the shark, and the skate called?

scyllite — A white crystalline substance of a sweetish taste, resembling inosite and metameric with dextrose. It is extracted from the kidney of the dogfish (of the genus Scylium), the shark, and the skate. (Webster's 1913.)

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