Page:Popular Science Monthly Volume 4.djvu/655

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crevice are seldom discolored more than an inch in depth, and the mineral adheres but slightly.

The dry dust of the mine is very inflammable, and two accidents from explosion have occurred. The asphalt contains about 76 per cent, of carbon, and yields about 100 gallons of oil per ton.

Agasslz's Successor.—It is rare that the mantle of the father sits worthily on the son. Especially is this true when the father has been signally eminent in pure science. Happily, indeed, is it for America, and for biological science, that the vast plans of the late Agassiz are to be continued, as far as possible, on the grand scale upon which his great mind projected them. The worthy successor of Prof. Agassiz is his son Alexander, whose name, in zoological investigation, is already acknowledged as a bright light in the Old World and the New. One of the most thoroughly worked-out monographs, so far as it is carried, and the most sumptuously gotten up, is the one recently published by Mr. Alexander Agassiz, containing his researches and memoirs on the Echinoderms, and which won for him the first award of the Walker prize of $1,000, by the Boston Society of Natural History. Mr. Alexander Agassiz is to succeed his father in the conduct of the Penikese Normal School of Natural History. That great institution, the pride of Massachusetts, and the envy of the savants of the Old World, "The Museum of Comparative Zoology," at Cambridge, Mass., has been placed under the direction of Alexander Agassiz and Mr. Cary, "both of whom are thoroughly conversant with Prof. Agassiz's plans with regard to the museum, and familiar with the collections." Thus, while all must lament, as a great loss, the demise of that wonderful man, yet a deep solicitude has been removed from many minds as to the fate of the professor's plans.

Lime-Soils and the Potato-Rot.—A writer in the Chemical News is led, by analysis of diseased and sound potato-tubers, to ascribe the potato-rot to a deficiency of lime and magnesia in the soil. Different observers state the percentage of magnesia in the ash of sound tubers at from five to ten per cent.; in the diseased tubers analyzed by the author it was only 3.94 per cent. Analysis of sound tubers shows over five per cent, of lime, but in the ash of diseased tubers the author found only 1.77 per cent. A similar observation was made some years ago by Prof. Thorpe with regard to diseased and healthy orange-trees; in the former there was a deficiency of lime and magnesia.

It was shown, by the late Dr. Crace Calvert, that lime is one of the few known substances that are capable of altogether preventing the development of fungi in organic solutions. He does not give any experiments relating to the action of caustic magnesia on fungi; but doubtless that action will be found to be similar.

"Here, then," observes the author, "is a curious and significant fact. Diseased potatoes are deficient in lime-salts, and lime prevents the development of fungi. May not the development of fungi in the vessels of plants be furthered by this deficiency? The circumstances are such as scarcely to leave room for doubt. So far, then, theory and practice agree: lime has been found by experience to be useful in preventing the disease, and it is likely that magnesia will be found to have a similar effect"

Clay Wasp-Nests.—All the American species belonging to the genus Polistes (wasps) have been considered paper-nest builders; but P. K. Uhler, at the Portland meeting of the American Association, described a species which build nests of clay. This wasp is of dark-brown color, with yellow bands across the abdomen, and with yellow feet. The insect builds a nest of cylindrical shape; and a number of these cylinders were found in the stump of a decayed tree, in Charles County, Md. The central cavity of the stump—which was about five inches in diameter—contained thirty-three of these peculiar structures. They were of yellow clay, generally about half an inch in diameter, and varying from two to five inches in length.

The nest, or more properly the receptacle for the egg and young, is constructed in the following manner: The adult wasp works some wet clay into an oval pellet, and carries it to the place where the nest is