. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. CYTO-EM BRYOLOGY OF SEA URCHINS. I 59 In 1900, Herbst challenged this idea of the Andrews with experimental data. In his well-known experiment using Ca-free sea water, lie found that the hlastomeres fell apart on the dissolution of the hyaline plasma layer in the absence of Ca++ ions. From this, he proposed that the hyaline plasma layer was a sort of "Verbindungs- membran" which binds the blastomeres together. But Herbst did not commit himself to any definite opinion concerning more concrete details of this functio
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. CYTO-EM BRYOLOGY OF SEA URCHINS. I 59 In 1900, Herbst challenged this idea of the Andrews with experimental data. In his well-known experiment using Ca-free sea water, lie found that the hlastomeres fell apart on the dissolution of the hyaline plasma layer in the absence of Ca++ ions. From this, he proposed that the hyaline plasma layer was a sort of "Verbindungs- membran" which binds the blastomeres together. But Herbst did not commit himself to any definite opinion concerning more concrete details of this function. As a matter of fact, this point continues to remain vague. Chambers (1925) proposes that in Echinarachnius parnia, the hyaline plasma layer serves simply as a bag, since the blastomeres can be moved freely within it with a microneedle. Gray (1931) maintains a more complicated view. He believes that the hyaline plasma layer of sea urchin eggs is composed of an outer gel part and an inner sol part, the second of which directly surrounds the blastomeres. In another study on the gills of the mussel, Mytilus cdulis, he successfully demonstrates that the intercellular matrix holds the cells together. Unfortunately, Gray's connection with these two originally separate observations seems somehow to have resulted in a confusion of their component parts, giving rise to the misconception that the inner fluid portion of the. 1. (A) A fertilized sea urchin egg in a calcium-free medium showing the halo- layer (after Herbst). (B) A fertilized sea urchin egg in sea water showing radial lines running across the intact hyaline plasma layer (after Gray). (C) Enlargement of (B). hyaline layer of sea urchin larvae acts as a cementing agent between the blastomeres. It is obviously a questionable procedure to assign a cementing role to a fluid substance. As can be clearly seen in Figure 5, the outer gel part remains extended over the furrow instead of inserting itself between the blastomer
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
