TRANSACTIONS OF THE SECTIONS. 83 



bark being removed is tbe destruction of the tree. Plantations are liable to be so 

 injured until they are of more than twelve years' gi-owtli. Should there be auy trees 

 of holly their bark is almost wholly removed. It is in the winter months that the 

 destruction chiefly takes place, especially when the ground is covered with snow. 

 In the examinatiou of hundi'eds of voles obtained from the Urumlanrig plantations 

 the author distinguished two species : the one corresponds to the ArvicoJa pnitends, 

 the other to the A. cujrestis. The former bears but a small proportion in number to 

 the latter. There can be little or no doubt that the enormous increase of voles is 

 owing to the relentless extirpation of rapacious birds, and especially of the 

 weasles. While natm'e gave unlimited fertility to the Eodentia, she boimded their 

 destructive increase by the caruivora ; and it is not wise for man, for the sake of 

 sport, to distm-b that order. Nature will not suffer him with impunity ; the 

 forests will become blighted, and the laud overrun with vermin, unless he ceases to 

 destroy indiscriminately the hawks, the owls, and the weasles. 



On certain Simulations of Vegetable Growths by Mineral Substances. 

 By John Deakin Heaton, M.D. 

 Several observers have noticed the curious arborizations which are developed 

 upon crj'stals of various salts when immersed in a solution of silicate of soda, 

 varyiugin form and other characters. Sulphate of iron seems to be the salt whose 

 crystals, when so immersed, produce the most free and beautiful forms ; and the 

 observations noticed had been made with this salt. If small fraoments of these 

 crystals be dropped into a solution of silicate of soda, formed by diluting the 

 commercial solution with about tAvice its measure of water, and having a density 

 of about 1-065, very beautiful arborizations will soon begin to shoot perpendicidarly 

 upwards, attaining the height of 3 or 4 inches in a few hours, consisting of trunks 

 subdividing and ramifying into branches of the greatest delicacy, and exactly re- 

 sembling a miniature forest of leafless trees, or imitating a mass of confervse, the 

 mode of ramification and the rapidity of growth varying with the density of the 

 solution used. If a much weaker solution be used, formed by diluting that of the 

 strength previously employed with two or three times its own measure of water, 

 and the crystal be suspended by a thread just below the surface, instead of being 

 allowed to drop to the bottom, roots will shoot downwards to the bottom of the glass 

 jar containing the solution, but there will be no growth upwards. By using a 

 solution of an intermediate strength the author had sometimes obtained contorted 

 fibres, like roots, growing downv/ards, and stems growing perpendicularly upwards 

 on the same crystal, suspended in the middle of the solution. The branches which 

 grow upwards, like the ascending stem of a plant, do not owe their tendency to ascend 

 to their having a lower specific gravity than the liquid in which they are formed ; 

 on the contrary, when broken from their support, they at once sink to the bottom 

 of the liquid. The same is true with respect to the downw^ard roots, which sink 

 to the bottom when detached from the crystal on which they form. They are very 

 friable, but have sufficient strength to retain their form for some days if not dis- 

 tiu-bed ; but when lifted out of the liquid, thej' collapse and fall to pieces. Both 

 silex and the salt of iron enter into their composition, as is evidenced by their 

 colour, which is various tints of olive or bluish green, and their- brittle insoluble 

 character. The weaker the solution the more silex and the less iron enters into 

 their composition, the branches being of a paler colour, or almost white, according 

 to the strength of the solution. Examined microscopically, the ultimate ramifica- 

 tions are foimd to be cylindrical, but gradually tapering to fine needle-like extre- 

 mities, and tubular throughout ; the walls being formed of a delicate inciustation, 

 have no appearance of crystallization, but are finely granular. They subdivide like 

 the branches of a tree ; sometimes they are irregularly contorted ; sometimes two 

 adjacent parallel branches unite, and again separate just as we see in the threads 

 of microscopic conferv£S, the tubular formation, however, being continuous through- 

 out. The tubular character is equally apparent in the roots ; but their terminations 

 are more abrupt, sometimes club-shaped. 



These phenomena present strong resemblances to the modes and forms of 

 growth of bodies belonging to the ■vegetable kingdom of organic nature. The 



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