YOLK

In Physiology, that portion of the )rimary yolk of the egg which is to be a imilated by he derivative germ-cells in the formation of the germna . In some animals the whole yolk is so a imiatcd; in others, as e. g. the bird, only a very small )ortion; that, viz. which is included in the germ-ma )r " cicatricula." [s. 1388]