Page:Popular Science Monthly Volume 4.djvu/781

Rh the consumption of beer is steadily increasing in spite of the advance in prices, and he is convinced that this state of things will continue, no matter what weight of argument may be brought against it. "Condiments of this kind," says he, "are often, no doubt, the occasion of real waste, but yet the majority of mankind can always, to their great profit, find, by observation and self-control, the proper amount of them to consume"

Sensation and Motion in Plants.—Treating of the vital phenomena which are common to plants and animals, the eminent French physiologist, Claude Bernard, observes that Linnæus's criterion of animality, viz., sensibility and mobility, is not in accord with facts. There are many plant-forms on the boundary between the animal and the vegetable worlds, for instance, the zoospores of the algæ, which have the power of motion. Then the antherozoids, particularly the œdogonium, studied by Pringsheim, manifest the faculty not only of motion in general, but even of motion toward a definite object—in other words, show all the appearances of voluntary movement. As instances of mobility in plants, the author further cites the movements of the stamina of the Berberis (barberry), the Drosera, the Dionæa muscipula (fly-catcher), and the oscillating sainfoin (Hedysarum gyrans).

Sensibility too is found in several plants. The Mimosa pudica (sensitive-plant) is the most prominent instance of this. This plant reacts against any irritation by folding up its leaves, which again are spread out soon after the exciting cause is removed. It is a curious circumstance that most of the agents which excite sensibility in animals have a like effect on the mimosa: thus it is affected by sudden shock, by burning, by the action of caustic, by electrical discharges, etc. Nay, the same agents, such as chloroform and ether, which deaden sensibility, or assuage pain in animals, destroy the mimosa's power of reaction. Vegetal anæsthesia is produced by the same means as animal anæsthesia.

There are other plants besides the Mimosa pudica which manifest this curious property of reacting against irritation, for instance, the leguminosæ of the genera Smithia, æschynomene, desmanthus, Robinia pseudacacia and the Oscalis sensitiva of India. From all this it follows that the power of movement and sensibility are functional properties which cannot strictly serve as a distinction between the vegetable and animal worlds.

Is Sex determined by Nutrition?—Mr. Thomas Meehan exhibited to the Philadelphia Academy of Natural Sciences specimens of the Juglans nigra (black walnut), with a view to showing that sex in plants is the result of the grade of nutrition, the highest grades of nutrition or vitality producing the female sex, and the lower grades the male. Examining a black-walnut tree at the flowering season, even the superficial observer will perceive three grades of growing buds. The largest buds make the most vigorous shoots. These seem to be wholly devoted to the increase of the woody system of the tree. Lower down the strong last-year shoots are buds not quite so large. These make shoots less vigorous than the other class, and bear female flowers on their apices. Below these are seen numerous small, weak buds, which either do not push into growth at all, or, when they do, bear simply the male catkins. As some naturalists hold that the feeble condition of these lower shoots is the result of their bearing male flowers, Mr. Meehan invited attention to the specimens themselves as conclusively proving the contrary. He was fully satisfied that any one, who would go out into the woods and fields for facts fresh from Nature, would see that there is not so great expenditure of vital force in the production of male flowers as there is in that of female flowers, and thus all he had advanced on this subject was fully sustained.

It will be remembered that, in our June number, we recounted the observations of Mrs. Mary Treat on the subject of controlling sex in butterflies, from which it appeared that butterfly-larvæ developed into male or female butterflies according as they were stinted in food, or liberally supplied with it. Besides the very interesting observations of Mr. Meehan, we have now further confirmation of Mrs. Treat's results in a paper communicated to the Philadelphia Academy by Mr. Gentry. The latter author, in the