Murray on Atmospheric Electricity. 561 



tians, and is now preserved in the Kaaba of Mecca ; which stone, he says, 

 is one of the objects of adoration by the adherents of Ismaelism. It is sup- 

 posed by Burckhardt to be a piece of basalt, but probably an aerolite. The 

 author also describes what are called Ceraunkim scintre, or lightning tubes, 

 formed, it is supposed, by the descent of the thunderbolt in the earth vitri- 

 fying the sand through which it passes. One is mentioned of the length of 

 nearly thirty feet. 



Mr. Murray next adverts to the agency of electricity on vegetation. 

 That plants are susceptive of its influence is a reasonable, and a very gene- 

 rally received opinion ; but that it eifects all that has been attributed to its 

 agency, as causing the direct and retrograde motions of the sap in vegetables, 

 is perhaps still doubtful. Our author adopts M. Dutrochet's theory of the 

 motion of the sap. This is quite natural ; as no one but a profound electrician 

 can possibly understand such a theory. Here, it appears, Mr. Murray sur- 

 renders his own penetration and judgment entirely. He says, quoting M. 

 Dutrochet, " The roots absorb water, with such soluble matter as may be 

 present ; this flows upwards to the leaves, through the lymphatic tubes of 

 Decandolle, and which are found both in the soft and hard wood : this fluid 

 solution, as it ascends, absorbs laterally a portion of the already elaborated 

 and assimilated sap, to form the leaves." What leaves? those already 

 expanded, or such as are reposing in the bosom of the buds ? Mr. Murray 

 proceeds : " Being carried up to the leaves in spring, the sap there under- 

 goes a chemical change, by evolving oxygen by day, and carbonic acid gas 

 at night : thus assimilated, it again returns, descending through the bark 

 and soft wood, and giving off laterally in its descent elaborated sap, finally 

 changed into bark and wood." In other words, simple water, impregnated 

 with soluble matters existing in the soil, after being mixed with the essen- 

 tial sap of the tree, is afterwards changed into ligneous fibre ! Had M. Du- 

 trochet said that such supplies of watery food assisted to expand the lig- 

 neous vessels, and the various parts of the vegetable being, he would have 

 been easily understood ; because he, as a chemical and botanical philoso- 

 pher, as well as the no less enlightened Mr.Murray, should, nay, must, know 

 that all the fibrous structure of a plant is in existence for years previously 

 to the reception of that food which expands them into full developement. 

 The most gigantic oak, and every part of it, was once contained in the 

 narrow bounds of an acorn. Vegetable growth is only the enlargement of 

 preexisting components, urged forward by a combination of heat, light, and 

 moisture, assisted no doubt by the restless currents of electricity. The 

 *' organisable properties " of a homogeneous fluid is an imaginary assump- 

 tion that has too long diverted the students of vegetable physiology from 

 the truth. To a mind unfettered by specious theories, it appears an impos- 

 sibility that the simple element of water, united with gum, resin, sugar, or 

 any other quality essential to a plant, should ever become changed into the 

 fibrous or woody components of plants. Our author next speaks of, but 

 without describing, " the radiated tracheae of the wood." That there is a 

 lateral transfusion of both sap and air through the vascular or porous fibrous 

 tissues of both bark and wood, cannot be denied ; but if Mr. Murray means 

 that what are called the " medullary rays " in the grain of the wood are tubu- 

 lar tracheae, it is an oversight ; for, in fact, these rays are vertical partitions, 

 of extremely close texture, and are the glossy waves which are exposed by 

 the saw and plane in working panels in joinery. The bladder, fixed to the 

 end of a bleeding vine, swelling till it bursted, appears to be nothing more 

 than its being surcharged by the sap and gaseous air, evolved by the fer- 

 mentation and expansion of the juice of the tree. 



Among other effects attributed to electric action is noticed the very 

 common one of dead disbarked twigs of some kinds of trees bearing a 

 curious fringe of slender icicles in frosty weather. It it always seen in 

 beech woods ; and sometimes, though rarely, on the twigs of hornbeam and 

 alder. It is only seen on half-rotten wood, from which the bark h^s fallen 



