Studies on the Origin of Yolk: II. Oogenesis of the Scolopendra, Otostigmus Feae (Pocock)

Abstract

ABSTRACT In a previous paper (1924) on the egg of the centipede, Lithobius forficatus, one of us (V. N.) described two kinds of yolk, albuminous and fatty. The albuminous yolk is preceded by nucleolar extrusions of a remarkable type, and its origin seems to be associated with them, although no evidence could be adduced that they are directly transformed into the yolk. It was further shown that the juxta-nuclear Golgi apparatus fragments into small granules and small crescentshaped Golgi elements. The former grow in size and give rise to the fatty yolk. Miss S. D. King (1924) confirms the above account of the association of the albuminous yolk with the nucleolar extrusions, but in her opinion this type of yolk arises directly from these extrusions. With regard to the Golgi apparatus she admits that it fragments into small granules. Furthermore she describes fatty yolk :—’ the origin of this fatty yolk is doubtful, but it may possibly be connected with the Golgi apparatus, although no evidence in support of this theory has been discovered ‘. In our opinion Miss King is doubtful of the origin of fatty yolk from the Golgi apparatus, because ‘both Mann-Kopsch and Da Fano material was studied, but the latter gave such favourable results that it was used almost exclusively ‘(spaced words ours). Now it is well known that the Da Fano method fails to show fat in the finished slides, while the Golgi apparatus is preserved. On the other hand the Mann-Kopsch method preserves both Golgi apparatus and fat, and thus enables one to study the transformation of the former into the latter. Furthermore, Flem-ming-without-acetic, which Miss King has used, shows fat, but not the Golgi apparatus, at least in the egg ofLithobius. In a later paper (1926), however, Miss King has shown that ‘the formation of fatty yolk from the Golgi elements in O ni sous is strictly comparable to the process described by Nath in Lithobius… .’