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32. The white-flowered Thijlle with round woolly heads. 33. The Pyrenean woolly Thiflle, with glomcrated purple flowers. 34.. The common Carduus or polycantha. 35. The Spanifh polycanthus, with very fhort leaves, armed with very long prickles. 36. The yellow ccntaury-like corn Thijlle. This has been called by many, the yellow knapweed with prickly heads. 37. The hoary fez-Thi/lle, with very tall ftalks. 38. The hoary cretic Thijlle, with a yellowifh purple flower. 39. The hoary Portugal- Thijlle, with ulaied ftalks, and woolly heads. 40. The prickly round-headed Thijlle, called by feme the globular-headed jacea. 41. The fuccory leaved purple Spanifh Thijlle. 42. The hairy jagged-leaved Thijlle, with white flowers. 43. The powdered or dufty Thijlle. 44. The knapweed-leaved Thijlle, with fmall heads and three- pointed fcales. 45. The rockett- leaved Maltefe Thift le, with yellow flowers. 46. The Maltefe Tbiftle, with conglobated heads. 47. The Portugal-77>//7/<?, with large hairy corono- pus leaves, and yellow flowers. 48. The PortugaI-7"/;//?/?, with hairy, rigid, coronopus-leaves, and faffron- coloured flowers, 49. The yellow Portugal- Thiflle, with fmooth and rigid coronopus-leaves. 50. The rape-leaved cretic Thijlle, called by fome the prickly cyanus, and prickly knapweed of Crete. Tmrn, Inft. p. 440. feq.
Gentle Thistle, Cirjium, in botany, the name of a genus of plants, the characters of which are thefe : The flower is of the flofculous kind, being compofed of a number of oblong flofcules, divided into many Segments at their edges, and placed on the embryo feeds. Thefe are all contained in a icaly but not prickly cup ; and the embryos finally become feeds winged with down ; to this it is to be added, that the leaves are furrounded with foft prickles. The diftinguifhing characters of the Cirfiitm and jacea are therefore thefe : The Cirjium has prickly leaves, and not prickly cups, and the jacea lias no thorns either on the leaves or cups. The fpecies of Cirjium, enumerated by Mr. Tournefort, are thefe: r. The great Cirjium with afphodel-roots. 2. The great Cirjium, with a large fmglc head, and purple ftamina. 3, The great Cirjium, with a large fingle head, and white ftamina. 4. The great Cirjium, with a fingle large head, and hoary divided leaves. 5. The great Cirjium, with a fin- gle large head, and with green fmooth leaves much divided. 6. The hoary large Cirjium, with fingle heads, with large fcales. 7. The Cirjium with fmall fingle heads. 8. The Cirjium with fmooth leaves and compact flowers. 9, The Cirjium with harrow and undivided leaves. 10. The com- mon narrow-leaved Cirjium. 1 1. The broad-leaved meadow Cirjium, with afphodel-roots. 12. The afphodel-rooted meadow Cirjium, with finely divided leaves. 13. The pur- ple-flowered Cirjium, without a ftalk. 14. The lilver-fpotted Cirjium. 15. The purple -flowered hcld~CirJiu?n, with creep- ing roots, and fow-thiftle leaves. 16. The white-flowered Held-Cirjium, with creeping roots, and fow-thiftle leaves. 17. . The creeping-rooted fow-thiftle -leaved fe\d-Cirfium, with tuberous ftalks. 18. The common many-headed meadow Cirjium. 19. The broad-leaved Cirjium, with burdock heads. 20. The low narrow-leaved Cirjium. 21. The mercury -leaved alpine Cirjium. 22. The Cirjium with very large leaves, of the fhape of thofe of the ferratula. 23. The many-headed Cirjium, with a winged ftalk, and finuous leaves. 24. The alpine Cirjium, with lefs divided leaves, armed with very frequent and long prickles. 25. The three- headed alpine Cirjium. 26. The purple- flowered acanthoide alpine Cirjium. 27. The acanthoide mountain Cirfium, with yellow flowers, 28. The many-headed meadow alpine Cir- jium, with afphodel-roots. 29. The many-headed alpine Cirfmm, with fmall purple flowers, and prickly ftalks. 30, The tall Pyrenean Cirjium. 31. The oriental Cirjium, with jagged leaves. Town. Inft. p. 447.
Torcb-TmsTLE. See the article Torch.
G/j^-Thistle. See the article Echinopus.
Thistle Fly, in natural hiftory, a fmall fly produced from a fly-worm, hatching in the protuberances of the carduus has- morrhoidalis. In the protuberances of this Thijlle, while they are clofed in all parts, the worm of this fly, from whofe injuring it, at the time of depofiting the egg from which it was hatched, the protuberances arofe, undergoes its laft transfor- mation. It here makes of its ownfkin a fhell, inform of an egg, within which it puts on the nymph ftate. When this nymph becomes a living fly, the lead part of its difficulty is the finding its way out of this fhell ; it has a much ftronger prifon than that, and before it can obtain its liberty, mult force its way through the much more clofely compacted fibres of the protuberance of the vegetable. It has, however, no other means of doing this difficult work, but that of inflating its head, and throwing out the bladder or muzzle with which all thefe creatures are provided in this ftate. See the articles Nymph, Museau, and Thistle-GV//j-, infra. This is a difficult operation, and many of the creatures perifh in the attempt; but what much forwards the fuccefs of it, in many cafes, is, that the ftalk of the Thiflle often becomes naturally half rotten before the time of the "fly's egrefs. Reau- mur, Hift. Inf. vol. 4. p. 338.
TmsTLE-Galls, a name given by the more accurate authors to 'the protuberances on the ftalks of a fpecies of Thijlle, called
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by authors, carduus btzmorrhoidalis, from thefe tubercles, which are fuppofed to refemble thofe of the hemorrhoidal veins, in pcrlbns fubjecf to the piles. Thefe have been fup- pofed a natural production of the plant ; but they are far other- wife. The whole hiftory of them is, that the juices of this plant, being peculiarly agreeable to the worms or a certain fpecies of fly, that creature always depofks its eggs on the ftalks i and the young ones, when hatched, gnaw their way into the fubftance of the ftalk, and the copious derivation of the juice, occafioned by their fucking, produces the turbercles which are found on it. See Tab. of Infecls, N^. 28. Thefe tubercles are of a roundifh or oblong figure, and are of various fizes, from that of a pea to the bignels of a nutmeg ; they are much harder than the reft of the ftalk, approaching to a woody ftrudture ; when cut open, they are found to con- tain each feveral oblong and narrow cells ; thefe have no com- munication with one another, and are each inhabited by a fmall white worm, which has two hooks at the head ; with thefe it breaks the fibres of the plant, in order to get at its juices. When it has arrived at the time of its change into the nymph ftate, it ceafes to eat, and drawing up its body much fhorter than ufual, its fkin hardens, and forms a dell, under whicli it changes into a very beautiful two- winged fly. The wings of this animal are of a very lingular appearance ; they are whitifh and transparent in the middle, but furrounded at the edges with a border of black in the form of a chain of figures like the letter Z. When the fly is i'eca in fome lights, the white parts of the wing is loft, and the whole appears a circle of thefe notched figures.
The body and breaft of this fly are of a beautiful black, with fome flight variegations of yellow ; and the fhoulders are ele- gantly ftreaked with the laft colour. The anterior part of the head is white, which gives the creature a very fingular ap- pearance, and its back part is edged with a fine yellow down or hairynefs. The antenna; are reddifh ; and the legs are in part black, and in part of a fine clear brown. In obferving the changes of the worms of thefe galls, there are often ob- ferved fome which go through them in a different manner from, the reft, and finally produce a very different fpecies of fly. Thefe are the progeny of the eggs of fome other fpecies of fly, whofe worm being carnivorous, is lodged by the art of its parent, while it is yet in the egg ftate in the fubftance of this gall, there to prey upon the defenceless inhabitants. There are many other fpecies of galls, the inhabitants of which are expofed to the fame fort of enemies. In thofe it is com- mon to find the proper inhabitant and the devourer in the fame cell ; the one feeding on the juices of the plant, the other on its juices ; but this is not the cafe here, thefe worms imme- diately deftroying the proper inhabitants, and being found al- ways alone in their cells. Reaumur, Hift. Inf. vol.6, p. 221.
THLASIAS, a term ufed by the antients to exprefs an eunuch made by a compreffion or contufion of the tefticles, not by the cutting them out.
THLASIS, a word ufed by the antients to exprefs either a con- tufion without a wound, or a wound made by fome blunt in- ftrument, which contufed the parts.
THLASMA, a word fometimes ufed like tblafis, to exprefs a contufion either with or without a wound j fometimes applied particularly to a recefs of the cranium inward without a fracture, an accident principally affecting children.
THLASPEOS Semen, in the materia medica, the name of a feed produced by the common tblafpi arvenfe Jiliquis laiis, or com- mon treacle muftard. See the article Thlaspi, infr. It is a plant of about eight inches high ; the leaves are broad and oblong, and the flowers are white, and each compofed of four leaves. The feed-veftels are broad asd flat, and the feeds fmall and dark coloured. It grows wild in England, but is not very common.
The feed mould be chofen clean and frefh, of a reddifh caft, and very ftiarp, and biting on the tongue. Great care ihould be taken in the buying this feed, becaufc it is often adulterated, and the feeds of common garden crefTes are too frequently fold in its place. It is an ingredient in feveral of our fhop compo- sitions, and is efteemed attenuating, deterfive and aperient, and is faid to promote urine, and the menfes, and to expel the after-birth. Lemery, Diet, of Drugs.
THLASPI, Treacle MuJlard, in botany, the name of a genus of plants, the characters of which are thefe: The flower con- ftfts of four leaves, and is of the cruciform kind. Thepiftil arifes from the cup, and finally becomes a roundifh fruit, of a flatted fhape, and ufually terminated all round with a foliaceous edge fplit at the extremity, and divided by an intermediate membrane into two cells, which ufually contain a number of flat feeds. To thefe marks it is to be added, that all the Tblafpii have whole, not divided leaves, in which they evi- dently differ from the najlurtium, or crefs kind. The fpecies of Thlajpi, enumerated by Mr. Tournefort, are thefe: r. The common Tblafpi. 2. The fmaller hoary- leaved Tblafpi. 3. The Held-Tblafpi with broad pods. 4. The hairy podded Tblafpi. 5. The Tblafpi with heart- fafhioned pods. 6. The fecrodo-Thlafpi, or Tblafpi fmel- ling ftrongly of garlick. 7. The larger perfoliated field- Tblajpi. 8. The fmaller perfoliated fe\d-Tblafpi. 9. The little red-flowered rock-Tbiafpi. 10. The purple-flowered 3 alpine
