IX.—The Formation of the Germinal Layers in Teleostei

George Brook
1887 Transactions of the Royal Society of Edinburgh  
A little more than a year ago, I was led to conclude that the primitive hypoblast in pelagic Teleostean ova was derived mainly from the unsegmented protoplasm forming the floor of the segmentation cavity. In this respect my results were mainly in harmony with the researches of Lereboullet (21), Kupffer (18 and 19), Klein (16), Van Bambeke (3), and others, but opposed to the more recent investigations of Henneguy (10), Hoffmann (14), Kingsley and Conn. (15), Ryder (24), Agassiz and Whitman (1),
more » ... z and Whitman (1), and Cunningham (8.) At that time I adopted Agassiz and Whitman's name ofperiblastfor the subgerminal layer containing free nuclei, though I differed from those authors in my idea of the mode of origin of the nuclei. As, however, I regard the tissues derived from this layer as belonging chiefly to the parablastic group of His and Waldeyer, I propose to return for the present to the older name ofparablast.I was not enabled to trace the origin of this layer in my earlier investigations, and thus failed to grasp its significance. More recently I have had an opportunity of studying the development of several other types, particularly the herring and cod. In the herring the germinal mound is not formed until after fertilisation. Partly owing to this circumstance, and partly also to the early period at which the assimilation of yolk commences, the eggs of the herring are particularly well suited for a study of the parablast question.
doi:10.1017/s0080456800025539 fatcat:q7kylm3ltfejtewocac2zx2334