Yolk

[AS., geoleca, yolk]. I. The nutritive part of an ovum, consisting chiefly of Y.- cells or Y. -granules. Y.-sac, the umbilical vesicle, the sac containing the food of the embryo. 2. The yellow portion of the egg of birds. The yolk of the hen’s egg is the Vitellus of the U. S. P. (Ovi vitellus, B. P.), and forms a constituent of Glyceritum vitelli (U. S. P.). YOUNG’S RULE Young’s Rule. A rule of dosage in children. The dose is obtained by adding 12 to the age and dividing the result by the age, and making the quotient the denominator of a fraction the numerator of which is I. The fraction represents the proportion of the adult dose to be given to the child. Young-Helmholtz Theory of Color-vision. Color-vision depends upon the presence in ch760.xhtml z 668