Page:Cyclopaedia, Chambers - Supplement, Volume 2.djvu/135

 OAK

OAK

o.

OfCyd) —It was not, ftrictly fpeaking, the letter O, but, the figure of a circle O, or double COi by which the modern antients, in mufic, ufed to exprefs what they called tem- ■bo perfetto, or triple time. Hence the Italians call it circdo. This circle was fometim.es pointed, and fometimes barred, thus

-f=* or thus, — (B—

But thefe equally fignified a triple time, Brojjard. The feven anliphones, or alternate hymns of feven verfes, &c. fung by the choir in the time of Advent, was formerly called 0, from their beginning with fuch an exclamation. OAK, quercm, in botany. See the article Quercus. Holm-O^K. See the article Ilex. OAK-ffpphh a name given to the common galls, ufed in dying.

See the article Gall. OAK-leaf galls. Thefe are of feveral kinds ; the remarkable fpecies called the mufhroom gall, is never found on any other vegetable fubftance but thefe leaves ; and, bende this, there are a great number of other kinds.

The double gall of thefe leaves is very lingular in that, as the generality of productions of this kind affect, only one fide of a leaf, or branch, and grow all one way ; this kind of gall ex- tends itfelf both ways, and is feen on each fide of the leaf, in form of two protuberances, oppoiitc the one to the other. Thefe are of differently irregular mapes, but their natural fi- gure feems that of two cones, with broad bafes, and very ob- tufe points, though fometimes they are round, or very nearly fo. See Tab. of Infea S ,N° 25.

Thefe make their firft appearance on the leaf in April, and remain on it till June, or longer. They are at firft green, but afterwards yellowifh, and are fofter to the touch than many other of the productions of this kind : they are ufually about the fize of a large pea, but fometimes they grow to the bignefs of a nut. When opened, they are found to be of that kind, which are inhabited each by one infect only, and each contain one cavity. The cavity in this is, however, larger than in any other gall of the fize, or even in many others of three times the fize ; the fides of it being very little thicker than the fub- ftance of the leaf.

It would be natural to expect, in this large lodgment, a large infect, but what is ufually found is only a fmall brownifh fub- ftance, of a kidney -like fhape, looking like the feed of fome plant. This is hard and motioniefs ; but is, however, the chryfahs of an infect which may be found living "m the gall, when opened in an earlier feafon, and is a fmall white worm, owing its origin to the egg of a fly. This creature has a me- thod of depofiting its eggs within the fubftance of the leaf, and the young ones, when hatched, eating on each fide, form the double tumor.

The life of the creature in this ftate is but fhort, and its dura- tion in the chryfalis confiderably long. The ihell under which it panes this ftate is not made in the manner of that of moft other worms, of its own fkin, but is formed of the woody fi- bres of the ribs of the leaf, which it gnaws into fmall pieces, and forms into that fhape by means of a vifcous humour, fe- creted from its own pores. At length the fly makes its way out of this cafe by breaking off one end of it, and then eats itfelf a paiTage through the gal!, and flies at large. The flies hatched of thefe infects are very fmall, yet Mr. Reaumur has obferved them fo carefully, as to be able to diftinguifh three or four kinds of them.

The moft common fly produced of thefe galls, is a very beau- tiful fmall one, of the four-winged kind. Its bod,' and breaft are black; its wings gawfy, and colourlefs ; and its antennas confiderably long, and of the conic, granulated kind. The body of this fly \s very fhort. A fecond fpecies is very diffe- rent from this firft ; it is of a brown colour, much longer bo- died, and has antennae of the club kind. There is another which refembles this in fliape, but its body is of a fine mining green, with an admixture of a gold colour ; the wings of this exhibit all the rainbow colours in the manner in which they are feen on a bubble of foap fuds.

It is not eafy to afccrta'm the origin of the feveral fpecies of flies, which are, at times, feen in this manner to come out of the fame fpecies of galls. It feems the common courfe of na- ture, that only one fpecies of infe& forms one kind of gad; yet it may be, that two or three kinds may give origin to the fame kind. There is, however, another occafion of our fee- .', * n g different fpecies come out of different galls of the fame kind ; and this is the effect of the enemies of the proper inhabitants.

It might appear that the parent fly, when me had formed a gall for the habitation of her worm offspring, had placed it in an impregnable fortrefs : but this is not the cafe ; for it fre- quently happens that a fly as fmall, perhaps, as that which gave origin to the gall, produces a worm which is of the car- Suppl. Vol. II.

nivorous kind, as the other feeds on vegetable juices. This little fly, well knowing that where there is one of thefe pro- tuberances on a leaf, there is a tender and defencelefs infect within, pierces the fides of the gall, and depofits her egg within it. This, when it hatches into a worm, feeds uponthc pro- per inhabitant, and, finally, after devouring it, partes into the chryfalis ftate, and thence appears In the form of its parent fly, and is feen making its way out of the gall, in the place of the proper inhabitant.

On opening thefe leaf galls, which are properly the habitation only of one animal, it is common to find two, the ftrongcr preying upon the body of the other, and fucking its juices as it does thofe of the leaf; often it is found wholly employed in devouring its unoffending neighbour at once: this is probably the cafe when its time of eating is nearly over; and, in fine, when we And the gall inhabited by only one infect, or con- taining only one chryfalis, as it ought in its natural ftate to do, we are never certain that this is the proper inhabitant, as it may be one of thefe deftroyers who has eaten up the other, and fupplied its place. Reaumur's Hift. Inf. Vol. 6. p. 197, feq. Oak puceron, a name given by naturalifts to a very remarkable fpecies of animal of the puceron kind. The generality of fuch animals live on the furface of the branches and leaves of trees, and plants ; but thefe bury themfdves in the clefts of the oak y and fome other trees, and getting into the crevices, where the bark is a little feparated from the wood, they there live-ateafe, and feed to their fill, without being expofed to their common enemies.

Thefe are the largeft of all the fpecies of f.ucerons ; the winded ones are nearly of the fize of a common houfe fly, and the naked, or fuch as have no wings, though lefs than thefe, are yet greatly larger than any other fpecies oipucerons ; the winged and naked kinds in thefe, as well as in the other fpecies of pit- cerons,are all mothers, and great number of young ones maybe preffed out of the body of either kind, when gently fqueezed. The winged ones are black, and the others of a deep brown, or coffee-colour; they have the moft remarkable trunk of any animal in the world ; it is more than twice the length of their bodies, and has not its origin at the extremity of the head, as in other infects, but is fixed into the bread near the origin of the firft pair of legs. When the creature is walking, it car- ries this ftrait along the belly, and trailing a confiderable length behind it, but with the point turned up, that it may be out of the way of accidents, and be ready to fuck. When the crea- ture has a mind to fuck a part of the tree that is juft before it, it draws up, and fhortens the trunk, till it brings it to a pro- per lengthy and direction ; but when it fucks in the common way, it crawls upon the inner furface of the bark, and the turned up end of the trunk, which refc-mbles a tail, fixes itfelf againfi the wood that is behind it, or contiguous to its back, and fucks there. The extremity of this trunk holds fo fail by the wood, that v^hen it is pulled away, it frequently brings a fmall piece of the wood away with it.

The ants are as fond of thefe as of the other fpecies of pucerons, and that for the fame reafon, not feeding upon them, but on their dung, which is a liquid matter of a fweet tafte, and is the natural juice of the tree, very little altered. Thefe creatures are the fureft guides where to find this fpecies of puceron ; for if we at any time fee a number of thefe crawling up an oak to a certain part, and there creeping into the clefts of the bark, we may be auured that in that place there are quantities of thefe oak pucerons.

The mechanifm by which this trunk of the oak puceron is fhortened, is like that by which we alter at pleafure the length of our telefcopes which are compofed of fever.il parts running one into another. This trunk is, in the lame manner, com- pofed of three joints, which, at the pleafure of the animal, are received more or lefs into one another's cavities, and, in all ftates, are fo flexile, that the animal can bend, and direct them to any part at pleafure.

The laft joint of the trunk, or that which is fartheft from the body is terminated by a very hard and (harp point; it is made only to pierce into the fubftance of the hard wood, and as, if this had been hollow, it muft have been both weaker, and thicker, both which arc- great difadvantages in regard to its ufe, nature has made it folid. In this it departs from the general nature of other trunks of infects, which are always open at the end: but inftead of that, this has an oblong flit on its upper part, a little above the end ; by this means, it is able at once forcibly to enter the wood, and to imbibe its juices, t his flit is not to be perceived without the largeft magnifiers, but there is always to be feen a drop of tranfparent liquor on the place where it is, if the crea- ture be a little fqueezed when newly taken oft" from the wood. This whole trunk is beautifully tranfparent, and there are two long bodies like hairs feen within it. It is hard to guefs at G g the