Synopses & Reviews
Synopsis
Excerpt from Zoological Bulletin, Vol. 2
The first eggs examined, the frog's eggs in cleavage and gas trula stages, yielded when studied alive only the amoeboid movement described by Roux; certain sections, however, showed intercellular connections that lead me to expect filose phenom ena to be present here. A large number of sections of cleavage and larval stages in various frogs and in the salamander Ambly stoma punctatum were carefully studied. In many sections of the latter animal, prepared and kindly loaned to me by Prof. C. B. Wilson of Westfield, Mass., as well as in certain frog's eggs, un doubted intercellular connections exist; but as their filose nature is not demonstrated, they will be but briefly noticed here. In the larva when the medullary folds are closed and the split meso blast nearly fused on the ventral side, intercellular connections were seen between the large yolk cells, between mesoderm and mesenchyme cells, between the ectoderm cells on opposite sides of the nerve tube, between the ectoderm and mesoderm, and between the entoderni and mesoderm; in fact, cells in all germ layers and in each layer connect with those in another layer and with those in the same. Eliminating the deceitful appear ances produced by coagulation of liquids between cells, by coagulation of fixative, by vacuolization and shrinkage of the superficial parts of cells, by the throwing of? Of pellicles, by the edges of drops and vesicles, and by fragments of vitelline mem brane, as well as by scratches upon slide and cover glass, there still remained the above intercellular connections of undoubted protoplasm. These varied from fine filaments to broad bridges, and were either Clear or contained some of the pigment granules of the egg. That they were filose in nature was indicated by their proportions and mode of origin and insertion; yet there was not decisive evidence that they were not produced in other ways either in the normal egg or in the egg when dying.
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