Page:Cyclopaedia, Chambers - Supplement, Volume 1.djvu/778

 GAL

GAL

as exactly circular, as if a round piece of the leaf had been taken Out in each place by an inftrument. Mr. Reaumur, to whom the world owes the difcovery of this fmgular fpecies of gall, was led to the obferving it by meeting with leaves

thus pierced, and then examining others, till he found fome which had on them the hex galls, which give origin to thefe holes. '

Thefe are very frequently found in confiderable numbers, twenty or thirty being not uncommon on a fingle leaf. There 'are obferved in thefe places round fpecks, or parts of the leaf, of the fame fize with the holes in the others, which are of a brownifh colour, looking very different from the reft of the leaf, and arefurroundedbyanedge, or border, fome what thicker than the leaf, and of the fame brownifh colour j in the midft 'of thefe little brown fpots there always ftands a fmall pro- tuberance, which rifes above the furface of the leaf, as well on the under as on the upper fide ; this is the gall ; it is of the figure of a conic box, with a conic cove r, and is of the hardnefs of wood.

The place where this box is largeft, is where the lid joins 'on to the body, and this is always in that part where it 'touches the leaf. If this gall, or box, be opened, there is always found in it a fmall white worm, produced from the egg of a fly. The manner in which this gall detaches itfelf Jfom the leaf, is this : when the creature has fucked its nou- rifhment from the leaf for a confiderable time, the little brown fpot, in the midft of which the gall is placed, grows dry, and fhrinks, fo as to lofen itfelf in a great meafure from the ring, or border, which is fixed to the reft of the leaf, and every way furrounds it. While it is in this ftate, the creature makes fome violent motions toward the efcaping out of it, in order to getting under ground, to pafs into. the chryfalis ftate ; the confequence of thefe motions is the loofening the gall wholly from the leaf, fo that it falls out with the circular dry'd piece of the leaf, and the animal finds itfelf on the earth, into which it immediately creeps, as ibon as it has dif- engaged itfelf from its cover.

As this is the cafe, it is no wonder that the worm is always found in its own form, not in that of the chryfalis, when the gall is fixed in the leaf; and the confequence of the falling out of feVeral of thefe circular pieces from the leaf is, that there arc left fo many circular holes in it, each furround- .ed with a brown and thick' ring, which connected the leaf to the fmall piece which held the gall, while that remained frefh and fuccident. Reaumur, Hift. Inf. Vol. 6. p. 207.

Bramble Galls, a fpecies of galls found on the branches of the common wild bramble. Thefe are often no other than tumefactions of the ftalk, for the fpace of an inch, or thereabout, which fornetimes' form only fo many thick cylindric pieces ; at other times they are of the fhape of an olive, and fornetimes they affect only one fide of the branch : in all cafes, however, the tumid part, or gall, is much harder than tiie other parts of the bran'ch, which are in their natural ftate, Thefe galls are very common in.' June and July, ami in the other fummer months, and when cut, either longitudinally or tranfverily, they are found to be inhabited by a great number of worms of an oblong figure, and yellow colour ; thefe live in the interftices, which they make between the woody fibres, and thefe interftices they alio make them- felves, by eating away the fubftanceofthe wood ; for if the galls arc opened when old, they are found to have a large cavity filled with the fragments of the woody fibres, which the worms have eat to pieces ; and there are ufually twenty or thirty worms in every gall.

Thefe differ extremely from the worms of the common oak galls, not only in colour, but in ftructure and parts. The common ones have all two little hooks at the head, in the manner of many of the maggots of the common flies ; but thefe, on the contrary, have a fharp point of a brown colour, and of the hardnefs of horn, coming from the extremity of the head, with this they tear and break the woody fibres, and there is near its end a flit, which is evidently the mouth of the creature, and which ferves for the receiving and con- veying into the ftomach the fragments of wood, which it breaks off with the point.

In fome of thefe galls there are frequently found another fort of infect, which is a white worm, fomewhat different from the former, and is not the proper inhabitant of the gall, nor intended to feed on the wood, but has hooks and teeth, in the manner of many of the common flefh eating mag- gots. This is a deftroyer, that gets by accident into the lodg- ing of the other worms, and feeds on them. Mr. Reaumur is of opinion, that the yellow worms, which are the proper inhabitants of the gall, turn into two winged flies, and the devourers of them into fome of the four winged kind ; but this is only a conjecture founded on analogy, as he acknow- ledges that he never actually faw the changes of either. The proper inhabitants of this gall are evidently the progeny of a fly, which has a power of lodging her eggs in the fub- ftance of the wood, by means of the borer ia her tail. Reaumur, Hift. Infect. Vol. 6. p. 194.

Broom Galls. See the articleBRooM.

Lime Galls. See the article Lime.

Mujhroom Galls. See Mushroom.

Germander Galls. See Germander gttlls,

Goofeberry Galls. See Gooseberry.

Grape Galls. See Grape;

Oak leaf Galls. See Oak leaf galls,

Rofe Galls. See Rose.

Willow Galls. See Willow.

IPlndGALt. See Wind.

GA-Lh-mfecl, in natural hiitory, the name of a clafs of infects fo called, from their refemblancc to fmall galls, or vegeta- ble protuberances of a like kind upon trees. They are in- deed fo like thefe fubftances, as to have been by many mi- ftaken for them, and thought not of the animal, but of the vegetable kingdom. Thefe infects pafs a very great part of their life, even many months together, faftened ao-ainft the leaves or ftalks of plants, without any appearance of life or motion, and this is the time in which they acquire their ftated growth. They are in this ftate as immoveable as the branch they are fixed on, and feem to make a part of it. Their exterior form ia remarkably plain, and fimple, and the more the creature increafes in growth, the lefs appearance of life it fhews j and even when it has acquired its maturity, and is in a condition to depofit its eggs for the propagation of its fpecies, it then appears kaft of all of an animal form, and more, than in any other ftate, refembles a gall, or fuch vegetable protuberance. Not only the vulgar and incurious have been deceived by this appearance, but the accurate count Marfigli, among others, after very attentively examining- the gall-infers of one fpecies, remained femingly convinced that they were real vegetable excrefcences.

The gall-ivfefis are ufually found on the ftalks and branches of trees, ftirubs, and perennial plants. There are fo far from being particular trees or plants allotted for their production, that very few are without them, and even the fame fpecies are found on very different fpecies of vegetables. The figures and colours of thefe animals enable us to diftinguifh feveral diftinct kinds of them ; they are all very fmall, even at their full growth, and fome of them, in their perfect ftate re- femble little round balls, faftened to the branches of trees &c. by a very fmall part of their furface. Of thefe round ones fome fpecies never arrive at a fize beyond that of a pepper corn; others acquire that of a large pea; other fpecies of them are of the figure of a fpherc, part of which has been cut off, and thefe are fixed on the trees by the part feemintdy cut; others are of the figure of elongated fphercs, the greater axis of which is raifed above the branch; others are'fomc- what flatted, and more pointed at one end than at the other * others are of the figure of a kidney, and thefe are fixed by the part where the cavity is ; others refemble in figure, the half of an oblong fpheroide, and thefe alone furniih a large num- ber ; thefe are divided, as it were, along their larger axis, and have fome fort of refemblance to a boat turned upfide down.

There is nothing fmgular or ftriking in their colour; fre- quently they are of a paler, or deeper chefnut brown; fome of them are redifh ; and others have fomcthing of a violet -tinge; fome alfo are of a good black, and others of a yellow ground, undulated and ftreaked with brown; fome are alfo brown, veined with white.

Thefe creatures have fo little to attract the obfervation even of the curious, that they might probably have remained much longer unregarded, were it not that they multiply fo exceflively faft on fome fruit trees. The peach trees, in par- ticular, are fornetimes in a manner covered with them, and thefe of more than one fpecies; fome 'of the globular kind and. others of the boat figure. The branches thus covered look rough and fcabby, and the gardeners, fenfible that what- ever the things were, they muft be nourifhed at the expence of the juices of the tree,' have attempted to deftroy them. The leaves and fruit of thefe trees is often blackened by the wet that has run off from thefe infects; and our orange trees, which are frequently full of them, ftrftftirred up the at- tention of the more careful obfervers of them to clear them away : thefe are principally of that kind, whofe form is that of the inverted boat. MciTrs. de la Hire and Sedileau, were at the pains of making a fet of obfervations, of a very curious kind, concerning them : thefe gentlemen call this fpecies the orange tree bug, a name by which the gardeners alfo call them, tho' they have nothing in common with any known fpecies of that animal. See the Memoirs of the Academy of Paris, 1692. If many of the fpecies of thefe little animals, however, do mifchief to our fruit trees, there are fome other kinds of them, the value and ufe of which may very well make us amends; fince it is from one fpecies of thefe little creatures that the inhabitants of many places make fuch great gains gathering a harveft of them without the trouble or experice of lowing or cultivating. The kermes, fo well known by name though fo little truly underftood, is of this kind, to which both the phyfician and the dyer are fo greatly obliged. The greater part of the animals of this clafs acquiTe their full growth about the middle of May, or beginning of June at the utmoft; at which time of the year the branches ot peach trees, efpccially fuch as are but ill taken care of, arc found to abound with two kinds of them, the one round like a pepper corn, the other of the boat fhape. They are fornetimes

brown.