. Electro-physiology. Electrophysiology. 312 ELECTRO-PHYSIOLOGY CHAP. The reaction of ova, which are already at different stages of segmentation, is also interesting. Both in the ovum divided into two or more cells (Fig. 101), as in the morula stage, and again in the blastula, consisting of many little cells, each single cell of the surface shows " special polarisation" when the whole organism is submitted to current, inasmuch as " the cells lying only on the polar side of the ovum exhibit one polar zone, which is visible externally, while the equator takes up the free surface o
. Electro-physiology. Electrophysiology. 312 ELECTRO-PHYSIOLOGY CHAP. The reaction of ova, which are already at different stages of segmentation, is also interesting. Both in the ovum divided into two or more cells (Fig. 101), as in the morula stage, and again in the blastula, consisting of many little cells, each single cell of the surface shows " special polarisation" when the whole organism is submitted to current, inasmuch as " the cells lying only on the polar side of the ovum exhibit one polar zone, which is visible externally, while the equator takes up the free surface of the cell lying distal to the ; Further differentiation into smaller and fewer cells, in older blastuke and the gastrula, will, however, under the same conditions, once more bring about a collective equator between two collective polar zones, since a girdle from the poles to the farthest cells remains unaltered. The special polarisation of single cells in the early stages of segmentation would appear to be " bound up with a property which diminishes with their vitality," inasmuch as each attack which weakens the vital energy of the ovum also prevents the formation of special polar zones, wholly or partially, without, FIG. "Special ilowever effecting the characteristic " total polar- polarisation of an ovum in four seg- isation " of the entire cell aggregate. Thus Eoux tT action SrfTt'ro7i" remarked in segmented ova treated with weak alternating cur- carbolic acid, which produced no change of form rents. (Roux.) ... , externally, that while special polar zones appeared at the first moment of action of the current, they spread rapidly over the whole surface of the cell directly exposed to the cur- rent, so that on each side " a single polar zone, springing, bow- ever, in the upper hemisphere from rounded cells, appears; while the " general equator," marked off by two parallel sectors, lies between them. With stronger a
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