. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 316 A. DALCQ AND G. VANDEBROEK the egg should he examined. It is possible that the particle might eventually penetrate the cortical film and adhere directly to the under- lying granular cytoplasm. For the latter form, the morphological value of the polar spot is now established beyond any doubt and it would appear that Dalcq was justi- fied in basing merogony experiments on this indication of the animal- vegetative axis of the i-^i;. Sectioning of the ripe ascidian egg in various planes relative 1" this primary axi
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 316 A. DALCQ AND G. VANDEBROEK the egg should he examined. It is possible that the particle might eventually penetrate the cortical film and adhere directly to the under- lying granular cytoplasm. For the latter form, the morphological value of the polar spot is now established beyond any doubt and it would appear that Dalcq was justi- fied in basing merogony experiments on this indication of the animal- vegetative axis of the i-^i;. Sectioning of the ripe ascidian egg in various planes relative 1" this primary axis and subsequent fertilization. FIG. 4. KYo >iistruetii >n of a lixrd abnormal .Iscidicllii ;'. Fixation, Allen; Sections, 6M; Staining. Holland*.-. IVi^peetivc vieu a! 45 (method of ). a, b, c: the three maturation spindle>. The eosinophil Mibeortical material is stippled. of both pieces seems to be at present the >ole method of analysing the distribution of the potencies at that Mage. Kurther experiments have been carried on by the senior author during re-cent years and a short account of the results has been presented (Dalcq, 1935). This has led to a furtluT eytological study of the structure of the ripe egg, and to tin- discovery of a preexisting bilateral symmetry indicated by the arrange- ment of eosinophil subcorlical granules (the mate-rial of the future yel- low crescent) in the lonn ot a large crescent which is more developed on one side of the primary axis. This important feature of the organ- ization of the ripe Ascidiclla egg together with the variations in the structure of merogonic twin embryos, whose anatomy has been thor-. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Marine Biological Laboratory (Woods Hole, Mass. ); Marine Biological Laboratory (Woods Hole, Mass. ).
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
