474< General Notices. 



MISCELLANEOUS INTELLIGENCE. 



Art. I. General Notices. 



THE vital Membrane of a dicotyledonous Stem. — What is here and elsewhere 

 advanced by us, in opposition to what we have respectfully called the Knightian 

 creed, but which, with equal justice, we might have called the DeCandollean, 

 or Poiteauian, &c, cannot be well understood by our readers, unless we make 

 the following declaration. 



We believe that the vital or living membrane of a dicotyledonous stem is 

 a distinct organ, from whence all other growth proceeds : it is the origin of 

 every annual layer of wood, and of every layer of liber. It has three very 

 visible states of existence during the growing season ; first, as a thin gum or 

 mucilage ; next, of a thicker consistence in summer, when it receives the 

 name of cambium ; and, ultimately, becomes perfect wood and liber in the 

 autumn. Its structure of cells, tubes, and fibres appears to be complete from 

 the first, though it is not till near the end of the growing season that the 

 various parts of the organisation become visible. A few of the most recently 

 deposited layers of alburnum and liber, together with the vital membrane 

 itself, are the principal channels for the upward flow of the sap, out of which 

 are attracted the elementary gases necessary for the enlargement of the walls 

 of the cells and tubes, and for engrossing the ligneous fibres. The rapidity 

 of the flow of sap is always in proportion to the perspiratory powers of the 

 leaves and rising shoots ; for, unless there is an escape, and consequent vacuum 

 formed above, no supply can follow from below. 



That the vital membrane, in whatever stage of its annual growth it may be, 

 covers the whole exterior of the last year's alburnum, is perfectly evident, 

 and it may always be detected if looked for by frequent incisions. During its 

 growth it exhibits its entirety as a united slough or organised body, by pro- 

 truding from its station round the lips of a wound to heal it. If a band be 

 tied tightly round a stem or branch, the living membrane will endeavour to 

 escape from under the compression, by swelling into ridges on each side. It 

 sometimes appears oozing out at the base of cuttings, before its fibrous parts 

 are resolved into roots. It begins swelling at the base of a lofty tree as 

 soon as it does at the top ; and, in short, shows itself in so many different 

 ways, as leaves no doubt of its identity as a distinct member of the stem, 

 separate, and not at all to be identified with the sap, whether in its crude or 

 elaborated state. 



The above is but a very loose representation of our ideas on this very 

 curious subject. It is intimately connected with the business of pruning 

 trees, or we would not have mentioned it at all. In order that what we have 

 said may give no offence, we wish to have it understood as hypothetical only, 

 and as such recommend it to the notice of our young readers. Our old 

 friends, whether practical or scientific, do not like to be persuaded out of 

 their senses, nor to have the trouble, by abandoning their early-adopted code 

 of opinions, long and fondly cherished, to embrace another which has too 

 much novelty and obscurity about it. (M., in Gard. Gaz., Aug, 20. p. 542.) 



A Potting-Bench Chopper. (Jig. 51.) — One of the greatest improvements of 

 the present day in pot culture is the use of turfy, rooty, and comparatively 

 rough soil, instead of the finely-sifted mould which was formerly considered a 

 desideratum in potting and shifting greenhouse and hothouse plants. Among 

 other interesting objects which we saw at Dropmore, about a fortnight ago, 

 was the stout chopper, fig. 52. The length of* the blade is about 9 in., and 

 the diameter of the head of the hammer, attached to its back, is swelled out 

 from the back of the blade to about ljin. The blade is used for chopping up 

 turf or rooty peat, and the hammer for breaking any small stones that may be 

 in it ; for breaking pieces of free-stone or bone to be added to the soil ; and 

 for breaking fragments of pots, or other materials, to be used in drainage. It 



