MISCELLANY. 



121 



has hitherto been extracted, being silicates 

 of nickel and magnesia, while the others are 

 arsenio-sulphurets. They are found in ser- 

 pentine rocks, which are very abundant in 

 various parts of the island, associated with 

 diorites, amphibolites, etc. Sometimes they 

 appear on the various rocks as a beautiful 

 green coating ; sometimes they penetrate 

 the rocks, giving them a more or less in- 

 tense color; sometimes they form therein 

 threads, which may assume the importance 

 and regularity of veins ; and sometimes, 

 again, they occur in pockets. As might 

 have been expected, the nickel is associ- 

 ated with iron, chrome, and cobalt, these 

 metals, especially the two former, being 

 very abundant ; their stratification is analo- 

 gous to that of nickel, except where cobalt 

 is met with. The latter metal is associated 

 with manganese, forming pure masses, of 

 greater or less extent, in the midst of fri- 

 able arenaceous rocks, composed of feld- 

 spathic and magnesian detritus. 



Ige of Trees in Relation to Time of 

 Leafing. In the course of a discussion, in 

 the Paris Academie des Sciences, of the 

 question whether the annual buds of a tree, 

 as it grows old, preserve the characters of 

 youth or share in the old age of the indi- 

 vidual which produces them, it was stated 

 that, according to observations made by 

 Prof. Decaisne on the JRobinia pscudacacia 

 (common locust) of the Museum d'Histoire 

 Naturelle, the time of leafing does not vary 

 with age. At Pisa, results a little different 

 were obtained ; there the gingko (Salisburia 

 adiantifolia) and the walnut have been 

 found to produce their leaves earlier in the 

 season from year to year as they have ad- 

 vanced in age. On the contrary, the vEs- 

 culus hippocastanum, or horse-chestnut, is 

 more tardy in proportion as it grows older. 

 M. de Candolle, who was present at the 

 meeting of the Academy, quoted observa- 

 tions carefully made every year since 1808 

 on two chestnut-trees at Geneva ; these 

 trees have leaved invariably between the 

 ninety-third and the ninety-sixth day of the 

 year. He further quoted the instance of a 

 vine growing at Ostend. This vine has 

 been observed during thirty-three years, 

 and during the first eleven years it leaved 

 on the one hundred and twenty-seventh day 



of the year; in the second period of eleven 

 years, on the one hundred and twentieth ; 

 in the third, on the one hundred and sixth. 

 Thus there would 'seem to be a continuous 

 progression, the vine becoming more pre- 

 cocious in proportion to its advance in age. 



Effects of Electricity on Particles sus- 

 pended in Liqnids. Some interesting ob- 

 servations by Holtz on the effects of elec- 

 tricity on particles suspended in liquids are 

 recorded in Poggcndorff's Annalen. In 

 giving an account of these observations, 

 Holtz remarks that the " migration " of par- 

 ticles suspended in a liquid, subjected to 

 electric currents, has long been known, and 

 was thoroughly investigated by Quincke. 

 But in all cases of such motion Holtz finds 

 that there is, at the same time, a clinging 

 of particles to one of the poles. This is 

 sometimes so evident that one might con- 

 struct an electroscope on this principle for 

 ascertaining the polarity. Especially no- 

 table is the tendency of semen lycopodii 

 in insulating liquids, particularly sulphuric 

 ether, to cover the negative pole with a 

 thick coating; while sulphur, cinnabar, or 

 sulphide of antimony, in the same liquid, 

 only coats the positive pole. A simple 

 medicine-glass suffices for the experiment, 

 a conductor or half-conductor being intro- 

 duced through the stopper. The glass is held 

 in the hand, and the conductor brought to 

 an electric machine ; the phenomenon then 

 occurs. It is better, of course, to have the 

 bottom perforated for insertion of the sec- 

 ond pole, or to use an open glass, with the 

 two poles pushed down into it. Either a 

 frictional or an influence machine may be 

 used. 



Have Bees a Sense of Hearing ? Though 

 the best observers deny to bees the posses- 

 sion of a sense of hearing, a writer in 

 Newman's Entomologist relates an instance 

 in which a hive of bees appear to have 

 heard the summons of their queen. A 

 swarm of bees had been gathered into a 

 hive, which was allowed temporarily to rest 

 upon a table. On lifting the hive, in order 

 to set it upon the hive-board, the portion of 

 the table on which the hive had stood was 

 found to be covered with bees, which soon 

 began to run about, from their having been 



