Origin of Yolk in the Eggs of Luciola gorhami

Abstract

THE eggs of the coleopteran fire-fly, Luciola gorhami, found in the plains of the Punjab, have proved to be objects of rare value for the study of the problem of the origin of yolk. There are two kinds of yolk in these eggs: albuminous and fatty. The former arises directly from nucleolar extrusions of a remarkable type. At a very early stage in the growth period the nucleolus shows signs of intense activity and buds off numerous round bodies of different sizes, which are thrown out in the cytoplasm. The nucleolus continues to throw out these extrusions until the very last stage in oogenesis. At the beginning of this process the extrusions migrate towards the periphery of the egg-cytoplasm, where they grow in size, perhaps at the expense of food materials derived from the follicle cells.