. . FIG. 28.—Diagram to show the origin of the unpaired eye out of two eye-spots, theretinae being drawn down to form the lateral retinas of that organ. /, pigmentcells. The pigment in the eyes is not drawn. position, and to have been arranged so as together toform the cavity already described. The hypodermiscells can still be seen secreting the chitinous membraneof the under side of the water-sac. The retinae nowforming the unpaired eye seem to be connected withthe original hypodermis only through fine connectivetissue and pigment s
. . FIG. 28.—Diagram to show the origin of the unpaired eye out of two eye-spots, theretinae being drawn down to form the lateral retinas of that organ. /, pigmentcells. The pigment in the eyes is not drawn. position, and to have been arranged so as together toform the cavity already described. The hypodermiscells can still be seen secreting the chitinous membraneof the under side of the water-sac. The retinae nowforming the unpaired eye seem to be connected withthe original hypodermis only through fine connectivetissue and pigment strands, similar pigment cells also io8 THE APODID/E crowding between the retinae. Fig. 28 is a diagram toshow the way in which we suppose the unpaired eyeto have been formed out of a pair of simple hypo-dermal eyes. Further investigation must decidewhether the dorsal and ventral retinae and the largerposterior cell groups of the lateral retinae are laterdifferentiations of the same two original eyes or newdevelopments. In the inner ends of the retinal cells,
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Keywords: ., bookcentury1800, bookdecade1890, bookpublisherlondo, bookyear1892
