Chem. [mod. f. ALLANTO-IS + -IN chem. form. Cf. Fr. allantoïne.] A crystalline substance, C4N4H6O3, the nitrogenous constituent of the allantoic fluid.
1845. Todd & Bowman, Phys. Anat., I. 9. Allantoin, an analogous compound to urea.
1863. Watts, Fownes’ Chem. (1877), II. 412. Allantoīn … is found in the allantoïc liquid of the fœtal calf … It is produced artificially … by boiling uric acid with lead dioxide and water.
