T 11 Y 



4-20 



T I A 



by di*wtion, and are held together by fine cellular tissue 

 continued from that which invests the whole glund. The 

 tubules va; . rom half a line to three lines in dia- 



meter, and have simple or complex cavities filled with a 

 nirrky flu; ' "<>|-r , T/if .Imttnmy of thf 



Tfiymu* Gland) says that the lobules are arranged in 

 spiral lines so that the eland may be unravelled into a sort 

 of knotted rope of lobules, which are wound around a 

 central cavity or reservoir, with which the cavities of the 

 lobules communicate. But the existence of such a cen- 

 tral cavity is not generally admitted. 



The fluid contained in the cells of the thymus gland is, 

 in \oung and healthy animals, opaque and creamy. It 

 has been particularly examined by Mr. Gulliver (Appendix 

 to Gerber's General Anatomy), who has found that both in 

 its chemical composition, and in the abundance and struc- 

 ture of the globules which it contains, it closely resembles 

 the fluid of the lymphatic elands. 



Of the function of the thymus gland scarcely anything 

 probable is known. Whatever it be, it is performed most 

 actively during fcetal life and the first year of extra-uterine 

 life : for during this time the thymus gland grows at the 

 same rate as the rest of the body, its cells are full of fluid, 

 and the fluid is thick and abundant in globules. From the 

 end of the first to the end of the third year its size does 

 not materially vary; but after this time it gradually di- 

 minishes, and after the twelfth or fourteenth year it is rare 

 to meet with more than a slight trace of it. It is also of 

 considerable size and is full of fluid in hybernating animals : 

 and this, together with its activity during foetal life, has 

 suggested that its office is in some way connected with the 

 preparation of the blood, when respiration is either inac- 

 tive or has not commenced. But, in these same circum- 

 stances, digestion is not going on, and it is therefore just 

 as probable that the thymus gland may have the office of 

 preparing a fluid and' globules, like those of the chyle, 

 from the materials which have served for the nutrition of 

 the body and have been re-absorbed ; in other words, that 

 its function is analogous to that of the lymphatic glands. 

 This was the opinion of Hewson (Experimental Eiiifn 

 it is supported by the observations of Mr. Gulliver and 

 many others, and is on the whole more probable than any 

 other yet advanced. 



The thymus gland is rarely diseased. The only affec- 

 tions of it yet described are an unnatural enlargement of 

 it, and its persistence in the dimensions which it has in 

 fcetal life. When it is enlarged there is generally a more 

 than usual development of all the lymphatic glands; and 

 not unfrcquently there are at the same time signs of serious 

 general disorder of the health, such as rickets, hydro- 

 cephalus, &c. It has been supposed, especially by the Ger- 

 man pathologists, that a peculiar affect ion of the respira- 

 tion, which has been called Thymic Asthma, is the gene- 

 ral result of enlargement of this gland; but the connec- 

 tion of the two affections is not yet clearly established. 



THYO'XK. [HOI.OTHURIA, vol. xii., p. 2<j<>.] 



THYROID GLAND is an organ situated in the middle 

 and fore part of the neck, in front and by the sides of the 

 thyroid cartilage of the larynx (from which it has its 

 name), and of the cricoid cartilage and the upper part of 

 the trachea [LARYNX], to which it is closely fixed by 

 cellular tissue. It is composed of two chief lateral por- 

 tions or lobes, and a smaller portion or isthmus connect- 

 ing them. A fourth portion, which is long and slender, 

 ned the middle column or horn, usually passes 

 upwards from the isthmus in front of the larynx. The la- 

 teral lobes are of a somewhat pyramidal form, about two 

 inches long, and an inch wide at their bases. The whole 

 gland is proportionally larger in the embryo than in the 

 adult, and in women than in men. 



The substance of the thyroid gland is firm, fleshy, and 

 vry vascular. It receives a copious supply of blood from 

 two superior and two inferior thyroid arteries ; the former 

 are branches of the external carotid, the latter of the snb- 

 clavian arteries; their branches communicate freely in the 

 jliiud, and they are accompanied by veins and lymphatics 

 .responding size. The interior of the gland contains 

 mimci'UM very minute cells, lined by polished membranes, 

 and in young persons filled by a clear albuminous fluid, in 

 which, or in the walls of the cells, there are numerous 

 granular corpuscles. 



Of the function of the thyroid gland no more is known 

 than of those of the spleen and thymus gland, between 



which it seems, in structure, to hold an intermediate 

 place ; resembling the spleen in its va*cularity. which is 

 far greater than u required for \\> nutrition, and the thymus 

 in tin- existence of cells cont.iiiimg a fluid, and in its dcve- 

 lop.nciit during early life. \Vhiit has been said of their pro- 

 bable functions might be repented hen 1 . 



The thyroid ghrul is subject to several chances of struc- 

 ture, most of which, being attended with enlargement, are 

 comprehended in the name of bronchocele or gottre 

 [DKII.M HOCKLK], to which the reader is referred. In many 

 cases the cells of the gland are enlarged, and its structure, 

 which in health is with difficulty discernible, may in these 

 be easily demonstrated. 



THYSANO'PODA. [STOMAI-ODS, vol. xxiii., p. 81.] 



TIA'HA niijm or rn'iftac ,. a high kind of hat, which was 

 in antient times worn by the inhabitants of Middle and 

 :n Asia, especially bv the Persians, Paithian-. Ar- 

 menians, and Phrygians, 'flu-re were two kinds of 1' 

 the upright tiara was only used by kings, priests, and oilier 

 persons of the highest rank, and the upper part had Ire 

 quently the shape of a crown; the tiara worn by other 

 people was of a son and flexible material, so that it hung 

 down on one side, as in the case of the so-called Phry- 

 gian bonnet. (Hesychius and Suidas, s. r. j-capa.) The 

 tiaras of persons of high rank were of the most costly 

 colours, such as purple, and adorned with gold and pre- 

 cious stones. (Ovid, Metnnwrph., xi. 1H1 ; Valerius 

 Klaccus, vi. 699 ; compare Dictionary of Greek and Rom. 

 Aiitiq., under 'Tiara.') 



In modern times the term tiara is applied to the head- 

 dress of the popes, which is worn on solemn occasions, and 

 consists of a triple crown. Hence it is also used in a figu- 

 rative sense to designate the papal dignity. 



TIA'RA, Mr. Swainson's name for a genus of ' Mitrinse," 

 his term for the subfamily of testaceous mol'usks. the 

 shells of which are termed ' Mitres' by collectors. fVoLU- 

 nn.t:.] N.B. This generic name comes too near to FIAKM. 



TIARl'NI, ALESSANDRO, one of the most celebrated 

 painters of the Bolognese school, was horn at Bologna in 

 l.~>77. He first studied under Prospero Fontana. and, after 

 Fontana's death in l"i!)7, under Hartolonico (Vsi : but 

 having in a quarrel discharged a pistol or similar weapon 

 at a fellow-scholar, without however doing him any injury, 

 he was obliged to fly from Bologna. He went to Flui 

 and there engaged himself with a port rait -painter, for 

 whom he painted hands and draperies, and some of his 

 performances having attracted the notice of Domenico da 

 Passignuno, he was admitted by that painter into his studio 

 as a scholar. Tiarini remained with Passignano seven 

 years, and by (hat time acquired so great a reputation, that 

 he received invitations from Bologna to return to that city. 

 In Bologna his works excited universal admiration for their 

 invention and earnestness of character, and for their bold- 

 ness of foreshortening, correctness of design, and propriety 

 of colouring: the tone of Tiarini's pictures is sombre : he 

 used little red, and avoided gay colours generally. His 

 works, which are very numerous, consist chiefly in oil- 

 paintings; he executed comparatively little in fresco: 

 tln>>e in public places alone, in Bologna and its vicinity, 

 and in Mantua. Modcna, Kcggio, Parma, Cremona, and 

 Pavia, amount to upwards of two hundred: their subjects 

 are generally of a melancholy or serious nature. The fol- 

 lowing are the most celebrated : A Miracle of St. Domi- 

 nic, in the Capella del Rosario, in the chinch of San Do- 

 menico at Bologna, painted iu competition with Lioncllo 

 Spada, in which the saint restores a dead child to life ; the 

 exhumation of a dead monk, in the convent of San Mi- 

 ehele in Bosco ; and St. Peter repenting his Denial of 

 Christ, standing outside the door of the house of the high 

 1'iiest, with the Mocking of Christ in the background, 

 illuminated by torchlight. 



LudovicoCarracci. MUM style Tiarini ultimately adopted. 

 was a great admirer of his works : when hi first' saw Tia- 

 rini's picture of the Miracle of San Domenico, he is re- 

 ported to have exclaimed that he knew no living master 

 that could be compared with Tiarini. ."M. ini's 



pictures, out of Bologna, have been attributed to one or 

 other of the Carrac.ci : such was tin case with the cele- 

 brated Deposition from the Cross, now in the Gallery of 

 the Academy of Bologna, formerly in the church of 'the 

 college of Montalto : it is engraved in the work of Rosas- 

 11111:1, I-ii Pmacoteca della Ponteficia Accadenua delle 

 Belle Arti in Bologna.' 



