D, Each of the four segment-cells gives rise by division to a small pellucid cell.

The St Lawrence varies only a few feet in the year and always has pellucid bluish-green water, while the Mississippi, whose tributaries begin only a short distance south of the Great Lakes, varies 40 f t.

perforatum, small shrubby plants with slender stems, sessile opposite leaves which are often dotted with pellucid glands, and showy yellow flowers.

E, The cap of small cells has increased in number by repeated formation of pellucid cells in the same way, and by division of those first formed.

In consequence of its low refractive and dispersive power, colourless pellucid fluor-spar is valuable in the construction of apochromatic lenses, but this variety is rare.