3'2'2 OBSERVATIONS ON VEGETABLES. 



off without the least inconvenience. So oaks may be barked 

 while the leaf is budding ; but, as soon as they are expanded, 

 the bark will no longer part from the wood, because the sap 

 that lubricates the bark, and makes it part, is evaporated off 

 through the leaves.* 



RENOVATION OF LEAVES. When oaks are quite stripped of 

 their leaves by chaffers, they are clothed again, soon after 

 midsummer, with a beautiful foliage ; but beeches, horse- 

 chestnuts, and maples, once defaced by those insects, never 

 recover their beauty again for the whole season. 



ASH TREES. Many ash trees bear loads of keys every 

 year ; others never seem to bear any at all. The prolific ones 

 are naked of leaves, and unsightly ; those that are steril abound 

 in foliage, and carry their verdure a long while, and are 

 pleasing objects, -j* 



BEECH. Beeches love to grow in crowded situations, and 

 will insinuate themselves through the thickest covert, so as to 

 surmount it all : are therefore proper to mend thin places in 

 tall hedges. 



SYCAMORE. May 12. The sycamore, or great maple, is 

 in bloom, and, at this season, makes a beautiful appearance, 

 and affords much pabulum for bees, smelling strongly like 

 honey. The foliage of this tree is very fine, and very orna- 

 mental to outlets. All the maples have saccharine juices. 



GALLS OF LOMBARDY POPLAR. The stalks and ribs of the 

 leaves of the Lombardy poplar are embossed with large 

 tumours of an oblong shape, which, by incurious observers, 

 have been taken for the fruit of the tree. These galls are full 

 of small insects, some of which are winged, and some not. 



* A correspondent, in Loudon's Magazine, proposes a theory of the 

 ascent of sap. " The theory which I wish to prove," says lie, " is the 

 following : The sap, in its descent in the stem, becomes deprived of 

 some of its constituents, more especially of its aqueous part : this depriva- 

 tion is effected by the vital principle of the plant decomposing the aqueous 

 parts, and assimilating the resulting gases to its own constituents. As 

 the assimilation takes place, a partial vacuum is formed by the change 

 of gas to a solid form ; and this vacuum is immediately tilled with sap 

 rushing into it, according to the well-known law of the tendency of fluids 

 to rush into any cavity deprived of the presence of air" ED. 



f Great irregularity exists in the fall of the leaf in ash trees. Many 

 trees will already have cast their foliage, when others in the same hedge-row 

 eem scarcely to have at all suffered from the chilling influence of autumnal 

 winds. This cannot be attributed to difference of exposure, as we have 

 observed them almost alternately with each other, in full leaf and 

 denuded, for miles along a road side. ED. 



