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The yolk is pale green, and the animal pole is brown.

All the eggs are viewed from the animal pole.

The diagrams show the positions of the segmentation spheres and of the contained nuclei as seen from the animal pole.

After the ovum has finished its growth, and elaborated the yolk within itself, a peculiar change occurs in the small area free from yolk-- the animal pole, in which the germinal vesicle lies.

A furrow cutting deeper and deeper divides it into two; another follows at right angles to this, making the two four, and another equatorial furrow cuts off the animal pole from the yolk or vegetative pole.