Page:Popular Science Monthly Volume 41.djvu/441

Rh tea are used. But the drinking of this tea has been nearly if not quite abandoned. A study of its history has been made by Dr. E. M. Hale, who has examined all the references to it he could find, and has started an inquiry into the reason why it has been abandoned, and the expediency of reviving its use. Its leaf, according to the analysis by Prof. Venable, of the University of North Carolina, contains caffeine. It is not so pleasant in odor and taste as the Chinese tea; but it seems to have some salutary properties which the latter does not possess, and may perhaps be more cheaply obtained. Dr. Hale estimates the extent of the land over which it grows as about forty thousand square miles, and suggests that careful experiments in cultivation and manipulation might result in furnishing our markets with a product that would be found in many cases an acceptable and useful substitute for the more expensive imported teas.

Many-toed Horses.—The derivation of the recent horse's foot with one digit from ancestors with polydactyl feet has been carefully traced by Prof. O. C. Marsh in his published papers on that subject. Several instances have come to the author's knowledge of existing horses presenting more than one toe. Julius Caæar's horse had this peculiarity. Its feet are described by Suetonius as having been almost human, with the hoofs cleft like toes. "It was born in Caæar's own stables, and, as the soothsayers declared that it showed that its owner would be lord of the world, he reared it with great care, and was the first to mount it. It would allow no other rider." The main functional toe of each foot of the horse is the third digit, corresponding to the middle finger of the human hand. In addition to these, two "splint-bones," one on each side of the main cannon bone, are present beneath the skin the remnants of two other toes possessed by ancestors of the horse. One or more of these splint-bones may become enlarged below and support phalanges, forming another digit beside the main one, or, more commonly, developing into a small external toe, with hoof. The occurrence of such extra digits in the recent horse is much more frequent than is generally supposed. Prof. Marsh has examined several living animals presenting this peculiarity, and has received photographs, drawings, and detailed descriptions of others. The extra digit may appear on one foot, when it is smaller than the main digit, and is usually on the inner side on the fore foot. It may often be entirely under the skin, with the only external evidence of it a prominence, in which its form may be made out. A corresponding extra toe may be present on the other fore foot; a second extra digit may exist with the others, but outside the main digit; with the extra inner toes of the fore feet, another of equal or smaller size may be present on one or both of the hind feet, almost always on the inside; in rare cases, both fore and hind feet may each have two extra digits fairly developed, and all of nearly equal size; or sometimes, besides the extra toes already described, which appear to be the second and fourth, the first digit, or pollex, may be represented by its metacarpal, supported by a distinct trapezium, all beneath the skin. A large majority of the polydactyl horses known to Prof. Marsh in this country have been raised in the Southwest, or from ancestry bred there, so that their connection with the mustangs or semi-wild stock of that region becomes more than probable. The fact that the tendency to reversion is much stronger where animals run wild must be taken into consideration in discussing the question of the origin of these animals.

Temperature of Lake Waters.—The investigations of Mr. A. T. Drummond on the temperatures of some Northern lakes and rivers have shown him that the Georgian Bay is, in its main expanse, a large body of cold water whose temperature, at its greater depths, is not much influenced by the heat of summer, while the central and southern basins of Lake Huron, although also receiving surplus waters from Lake Superior, stand in the line of inflow of the warmer waters from Lake Michigan and of their ultimate exit by way of the river St. Clair to the lower lakes, and are consequently somewhat warmer basins. Among the details of observations recorded in his papers, we find that tests at the rapids of the Richelieu River at Chambly seem to show that the motion of the water during the mile of continuous rapid raises the temperature of the water perceptibly. Rapid currents have, however, the effect of equal