Page:Popular Science Monthly Volume 47.djvu/881

  seeds of many kinds will germinate and grow into independent plants if sown immediately after removal from the parent. This may be readily observed in wheat, and the same property is found occasionally in various other plants. Sometimes the seeds of pulpy fruits germinate in the fruit. The vitality of certain seeds is not impaired by floating and being partially submerged in sea water for as long as a year. Plants are growing at Kew from seeds that have been thus exposed. Some seeds will bear immersion in boiling water for a short time; but seeds of all kinds will bear for a considerably longer period a much higher dry temperature than they will soaking in water of the same temperature. Dry grain is equally impervious to cold. Some of the fir trees, especially of North America, bear the seed vessels containing quick seeds of many successive seasons; and only under the influence of forest fires or excessive drought do they open and release the seed. The unopened cones of thirty years have been counted on some fir trees; and it is averred that the seed vessels of some proteaceous trees do not open to shed their seed, under ordinary conditions, until the death of the parent plants. The stories of the germination of "mummy wheat" have not been confirmed; but kidney beans taken from the herbarium of Tournefort are said to have grown after having been thus preserved for at least a hundred years. Wheat and rye are said to have preserved their vitality for as long a period. Seeds of the sensitive plant germinated at the Jardin des Plantes, Paris, when sixty years old. If seeds retain their vitality for so long periods under such conditions, it is quite conceivable that seeds buried deep in the earth, beyond atmospheric influences and where there is not excessive moisture, might retain their germinative power for an indefinite period.

Cultivation of Dates at Tafilet.—The cultivation of dates and leather work form, according to Mr. Walter B. Harris, the sole industries of Tafilet, Morocco. The water for irrigating purposes is brought by many canals from the Wad Biz to the palm groves. The soil under the trees is carefully dug, and divided by low raised banks into squares from ten to twenty yards in extent. Into these, by removing a small part of the bank into which the water flows—for the canals are raised above the general level of the soil—a connection is formed with the canal and the land flooded, the water being allowed to proceed from square to square by removing portions of the dikes. The object of this irrigating of the patches separately is to avoid waste, only the portion which actually requires water receiving it; these squares are cultivated with lucerne, wheat, and barley where the shade of the palms is not excessive, and maize and palms, the latter of which are not so common as in other parts of the desert, for the dates take their place as the staple article of food of the people. Besides the palm supplying the people with provision, the coarser species of dates are employed for fodder, and constitute the chief food of such cattle as there are, and of horses and donkeys. The finer qualities are exported to Fez and Morocco City by caravan, the pack animals bringing in return wheat and European manufactures and rough iron. About ninety per cent of the export of Tafilet dates from Morocco go to London.



the construction of the new speedway at High Bridge, New York, a bed of quicksand was encountered, which much impeded the work. The difficulty was obviated by the artificial refrigerating process. A row of four-inch pipes was sunk a few feet apart to the depth of forty feet. These pipes were capped at the bottom, and inside them were inserted smaller pipes open at the bottom. Cold air was forced from a condenser through the smaller pipes into the larger and thence returned to the condenser. The air was cooled by expansion to a temperature of about—45° C, thus freezing the surrounding mud and wet sand, and checking the flow into the excavation.

of Liverpool, proposes to avoid the hardship of having—in the future—to remove from the marine service persons who may be found defective in vision by making the tests for their admission more stringent. He therefore suggests new rules providing that no boy or man shall lie allowed to enter the service until his form vision and color vision have been tested and found sufficient; that their certificate of eyesight be exhibited by seamen before they are permitted to sign articles; that color-blindness and defective vision be made in themselves reasons for breaking indenture 