496 Miscellaneous Intelligence. 



crease still further, or whether it will be more proper to fell it. 

 An exact ai^e cannot be assigned for each species ; but it has been 

 observed, that an elm situated in an insulated plantation may be 

 felled with advantage when between seventy and eighty years of 

 age. 



III. Sigjis of decay in a tree. When a tree becomes crowned, i.e. 

 when the upper branches die, it infallibly indicates, especially for 

 isolated trees, that the central wood is undergoing alteration, and 

 the tree passing to decay. When the bark separates from the 

 wood, or when it is divided by separations which pass across it, 

 the tree is in a considerable state of degradation. When the bark 

 is loaded with moss, lichen, or fungi, or is marked with black or 

 red spots, these signs of alteration in the bark justify suspicions of 

 alterations in the wood within. When sap is seen to flow from 

 clefts in the bark, it is a sign that the trees will soon die. As to 

 wounds or gutterings, these defects may arise from local causes, 

 and are not necessarily the result of old age. — Bihlioth. Phys. 

 Econom. 1826, p. 13. 



10. Structure of Plants. — M. Raspael has endeavoured to ascertain 

 what alterations are occasioned in a lengthened time by water, 

 acids, and heat, upon feculous teguments, and, consequently, 

 upon all vegetable tissues, which, according to him, are merely 

 vesicles similar to the teguments. The following are some of the 

 results which M. Raspael says he has obtained. After an ebul- 

 lition continued for eighteen hours, the teguments began to appear 

 as a layer of granules : continuing the ebullition, these granules 

 were successively detached from each other until the liquid no 

 longer offered traces of teguments, but merely globules from 

 the.-^A^th to 4^^th of a millemeter in diameter. These resisted 

 ebullition during eight hours per day, for a whole month. The 

 experiment was made in vessels almost close. 



The liquid being put into a flask half filled with air, was left ; 

 the granules required fifteen days for their precipitation, whilst the 

 untouched feculous integuments were almost entirely precipitated 

 on the third day, according to the quantity of fecula submitted to 

 ebullition. The liquid part of the contents of the flask did not 

 cease to colour iodine till a month after; the precipitated part con- 

 tinued to become coloured purple by iodine. Water without ele- 

 vation of temperature is competent to disintegrate the globules 

 composing feculous teguments, but requires two or three months to 

 manifest the action. 



Muriatic acid, out of contact of air, produces the same effect, 

 but only after a month's action, provided the experiment has not 

 been exposed to heat or light, the only difference in the experiment 

 is, that the globules become black and charred, but still remain 

 vesicular. 



