Figs. 11-14. Surface views of epidermis of Tradescantia discolor, from first appearance of stomata to maturity of the same.

Fig. 15. Cross section of about the age of No. 12, b.

Fig. 16. Cross section of the age of No. 13.

Fig. 17. Cross section of full-grown.

Fig. 18. Longitudinal section of the same.

X400. The arrows indicate the direction of the point of the leaf.

AQUEOUS PHENOMENA OF THE PRAIRIES.

BY PROF. H. W. PARKER.

THE igneous scenes of the prairies have become very common place in description. But where is there any account, either scien tific or popular, of the interesting aqueous phenomena, in winter and in summer?

How it may be in the region protected on the north by the Lake Superior highlands and affected by the air of the lakes, the writer does not know, except that the temperature is much modified. But in central Iowa intense cold is of frequent occurrence, and there are conditions along with it that often bring out the splendors and wonders which we associate with arctic scenes. Parhelia, or mock suns, at morning or evening, are common; without exaggeration it may be said that they equal the real sun in brilliancy, and are indeed blinding to the sight. After witnessing them, an eastern man regards all that he has seen of this phenomenon at the east as insignificant. So likewise, mock moons, and both lunar and solar halos, crosses, and far-extending complicated circles of light, with bright spots at the intersections, may be mentioned as sights by no means unusual, and often of great magnificence and duration, continuing a good part of the day or night. The writer remembers, for example, a circle passing through the sun and reaching horizontally quite around the sky, making part of a cross inscribed within another circle around the sun, there being also four tangent circles at the ends of the cross; and this was visible for several hours before and after midday. The cloudless sky of the West conspires with spicules of frozen vapor, to render these effects not rare; for the West, at least beyond the vicinity of the lakes, is bright and sunny at all seasons.

Feathery crystals, frequently of great size and beauty, and completely clothing every exposed object, are sometimes to be seen