talline concentric layers, and attain to eighteen or twenty inches in diameter. This, he thinks, is the greatest size they can attain. When so large as this, they press out the sides of the intestine, producing inflammation and violent pain, which causes the animal to roll about in agony, and, sooner or later, kills him. They consist mostly of phosphate of ammonia and magnesia, and the amount of organic matter is not great. This salt the author refers to the grain fed to the animals, and he raises the question whether grain is not for the horse a highly-artificial food. He is of the opinion that repeated doses of very dilute hydrochloric acid, say two to five per cent., in water or spirit, if it can be made to reach them, would quickly destroy the largest of these calculi. The lime in the water drunk by horses has nothing to do with the production of these concretions. It originates in the food, and is, in a large measure, due to a want of salt in the grain. Hence, working-horses that are highly fed should have lumps of salt to lick, and have salt in their food, and plenty of water to drink. The ventilation and drainage of stables is another important consideration. Many valuable beasts, after a hard day's work, pass the night in an atmosphere loaded with fumes of ammonia.
Abnormal Fruits.—Some abnormal fruits of the pear-tree, in appearance like very large acorns, having been exhibited at a meeting of the Academy of Natural Sciences of Philadelphia, Mr. Meehan took occasion to explain that a fruit is a modification of both leaves and branch. When a bud, he said, is being formed in the apple, pear, or similar trees, it may finally be either a flower-bud or a bud producing a new branch. Varying phases of nutrition decide this question. Exactly the nature of this variation we do not know; but we do know that the growth-force in the bud is arrested by some law of nutrition, and, instead of an elongated branch, what would be its series of spirals are drawn together closely, and the whole modified and made to form a flower. Thus, in the pear, it takes five buds to form one full cycle on a branch. When growth is arrested to form a flower, this first cycle is transformed into a five-lobed calyx, and generally this becomes much enlarged and fleshy, and covers all the other cycles of buds, which go to make up the inner layer of flesh terminating in the petals, carpels, or core, and so on. In the case under consideration the arresting force was imperfect. It had succeeded in forming the outer or calycine verticillate series of buds into a fleshy matter, giving what here might be called the cup of the "acorn;" but then the accelerating or branch-producing force gained a temporary advantage, and pushed on, forming the acorn-like centre, but only to be soon again arrested. This abnormal pear was, indeed, nothing more than an effort of the tree to produce a branch after a fruit had been decided on—a struggle which was finally decided in favor of the fruit.
Explanation of the Ball-Paradox.—Reuleaux offers the following explanation of the curious phenomenon of a ball being sup ported in air by a strong air-current directed obliquely upon it at an angle of 35° to 40° from the vertical: The pretty thin air-current, on reaching the ball, is deflected on all sides, and therefore more or less rarefied in its interior. Accordingly, the atmosphere presses the ball in the direction of greatest rarefaction, or the mean force of the rarefactions, toward the orifice. The weight of the ball acts vertically downward. Equilibrium occurs between the obliquely acting force of the current and the two forces just named, when the mean force of the latter is parallel to the action of the current. This can only take place when the ball has its centre under the axis of the current. There are then two forces which put the ball in rotation. If the finger or a rod be brought to the place of supposed minimum pressure on the ball, the latter is forthwith driven off (the vacuum being destroyed), or falls down.
Successful Case of Transfusion of Blood.—A case of successful transfusion of blood is recorded in the Lancet. The patient, a clerk, twenty years of age, was completely demented, hyperæmic, anæsthetic, and cataleptic; refused all food; dribbled constantly. The pulse was very feeble, rate 70, respiration 24. His state was one of profound
