Page:Popular Science Monthly Volume 9.djvu/139

Rh the soil. No flint or stone implements are to be found among them, and they produce a flame by rubbing two sticks together. Their intellectual capacity is so small, that they are unable to count or to discriminate colors. They are almost destitute of the religious sentiment, as well as of an appreciation of personal cleanliness, for they habitually eschew ablutions. They abhor theft and lying. But, perhaps the most remarkable trait in the character of the Weddas is the apparent absence of a faculty which is held to be peculiar to the human race that of laughter. It is stated that they regard the expression of mirth by others with surprise and disgust, and that no Wedda has ever been known to laugh.

Lettuce as Food for Silkworms.—A writer in Das Ausland states that, in the summer of 1873, a few silkworms, belonging to his children, were fed with lettuce for some time after being hatched, mulberry-leaves not being obtainable. The caterpillars ate the lettuce ravenously, but, when they were about half-grown, a supply of mulberry-leaves was procured, and this constituted their food for the rest of the season. The moths in due time spun their cocoons as usual, and the next spring the author himself determined to feed the silkworms only on lettuce. The young brood devoured the lettuce in great quantities, care being taken to leave no moisture on the surface of the leaves. The insects grew and went through their metamorphoses in the usual manner; a few only died, and they from carelessness in not wiping the leaves dry. The cocoons were of good quality, and the author intended to exhibit some of them at the Royal Agricultural Hall in Stuttgart. Time alone can determine whether silkworms will degenerate on being fed on lettuce. However this may be, the subject is one that is worthy of investigation.

Dredging for Amber.—According to an official report from Memel, Germany, an establishment has been organized for obtaining amber by dredging in the Kurische Haff, near the village of Schwarzorts, situated about twelve miles south of Memel. It has been known for many years that amber existed in the soil of this place, from the fact that the dredger employed by the Government for clearing away the shallow spots near Schwarzorts, which impeded navigation, brought up pieces of amber, which were duly appropriated by the workmen, and at the time no particular attention was paid to the matter. Some time afterward, however, some speculators associated, and made an offer to the Government not only to do the dredging wherever required at their own expense, but to pay a daily rent, provided the amber which they might find should become their property. This proposal was accepted, and the rent fixed at 15 thalers, and later at 25 thalers, for each working day. The dredging was begun with four machines worked by men, and one worked by horses. Judging from the extended business transactions in this matter, its results must have been extremely profitable. At present, the work is carried on with eighteen steam-dredges and two tug-boats, the whole managed by about 1,000 laborers.

Temperature of Germination.—It is generally supposed that the seeds of plants do not germinate at a temperature lower than 4° or 5° Cent. (40° Fahr.), but certain experiments made by Uloth, and published in the German botanical magazine, Flora, would seem to show that this opinion is erroneous. In Dr. Uloth's experiments the seeds of Acer platanoides and of Triticum germinated at a temperature not exceeding zero C. (32° Fahr.). In the winters of 1871-'72 and 1872-'73, he made the following experiments: He took two boxes and in each had a certain depth of water frozen into a block of ice. In these blocks he made furrows four millimetres deep, in which he sowed seeds of various plants, which were the same for the two boxes. He now covered the boxes with a plate of ice, and stored them away in two separate ice-houses. He then partly filled two boxes with soil, in which he sowed the same kinds of seeds. These boxes he also covered with plates of ice, and stored them in the same ice-houses with the others. Care was taken to have a good thickness of ice (over four feet) surrounding the boxes on every side, so as to provide against any elevation of the temperature. The boxes were placed in the ice-houses in January,