period during which it has already been proved by Mr. Buckland and Mr, Youl that the development of salmon may be safely retarded by ice. A large quantity of the ice surrounding the ova remained till the end of the voyage, so that the temperature of the ice-houses must have been kept very low throughout the voyage. The cases in which they were packed are described as "sodden," so that they did not suffer from dryness. Probably want of ventilation caused the failure of the experiment.
Ancient Glaciers of the Sierra Nevada at Lake Tahoe.—In the American Journal of Science for August is an interesting paper, by Prof. Joseph Le Conte, on the ancient "Glaciers of Lake Valley," in which is situated the well-known and beautiful Lake Tahoe. The great glacier which filled all the lower part of the valley had its source in the snow-fountains among the mountain-peaks at its southern end. The valley is a trough between two ridges of mountains near the top of the Sierras. It is 20 miles wide, 50 miles long from north to south, and is 3,000 to 3,500 feet deep; its lower half is filled with the waters of Lake Tahoe. This lake occupies an area of about 250 square miles, and is 1,640 feet deep.
On either side of the lake are mountains, but those which still show best the glacial sculpturings are on the westerly side. Some of these rise 3,000 feet above the level of the lake, and are between 9,000 and 10,000 feet above the level of the sea. The surface of the lake is at nearly as great an elevation above tide as the summit of Mount Washington. The ice at its greatest development filled the valley—a vast mer de glace—to a height of 300 or 400 feet above the present lake-level, and was therefore about 2,000 feet thick. It moved northward, and was discharged upon the plains; some of it evidently moved down the cañon through which the Truckee River now flows.
This glacier was fed by tributaries from the mountains, and these continued to flow after the great mer de glace had ceased to exist. Enormous mounds of débris, glacial moraines, occur between the lake-margin and the mountains, cut with wonderful regularity by water; and toward the southwestern portion of the lake occur those exquisite lakelets which add to the charm of the region. Of these. Fallen Leaf Lake, Cascade Lake, and Emerald Bay, are of wonderful beauty. The green waters of Emerald Bay contrast with the clear blue waters of Lake Tahoe. Lake Valley, in which Lake Tahoe lies, may not have been wholly scooped out by glacial action. Prof. Le Conte suggests that an area of depression may have been formed in the process of elevation of the mountains, which was enlarged and deepened by erosion.
American Grape-Vines and the Phylloxera.—Four years ago Prof. Riley went to France to study, on the spot, the grape-Phylloxera. Some of the scientific results of this visit—as the establishment of the identity of the European insect with that found in our own vineyards, and the American origin of the Phylloxera—are known to our readers; but the practical results are highly interesting and important. His experience, here, having taught him that some of our indigenous vines offered greater resistance to the insect than the European varieties, and that, with European vines, there was no hope of discovering a remedy which would prove practicable and satisfactory on a large scale, and under all conditions, he advised the French grape-growers, as one of the most promising means of restoring the ravaged vineyards, to import American vines, either for their fruit or as stocks for the French varieties. Results are fast justifying this advice. The insect continues to broaden the area of its devastations; and in many sections of Southern France, where but a few years ago the whole country was one great vineyard, the ground is now either entirely or partly devoted to other crops, to which it is poorly suited, or the vineyards are rapidly perishing. In spite of the large national reward for a remedy—in spite of the well-directed and persistent efforts of the government, and of the Academy of Science, to discover one—nothing but submersion, which is practicable to but a limited extent, proves effectual, and by degrees the fact is being acknowledged that all other remedies are futile. The American vines, however, are fast gaining ground, and the people begin to look to them as a means
