T I S 



499 



T I S 



Two Sicilies, but principally in the environs of Naples, 

 daring the years 1789 and 1700 ; now in the possession of 

 Sir W. Hamilton, published by William Tischbein, direc- 

 tor of the Royal Academy of Painting at Naples.' The 

 text, which is in French and English, is by Italinsky. 

 Tischbein published other works, and etched also several 

 plates, after Paul Potter, Roos, Rosa di Tivoli, Rem- 

 brandt, &c. As a painter his drawing was correct, and 

 his expression and colouring good, and he excelled in 

 drawing animals. He died in 1829. There were many 

 other artists of this family, of various degrees of merit, 

 but they are unknown beyond their own circles. 



(Fiissli, Allgemeines Kiinstler Lexicon; Kugler, Hand- 

 buck der Geschichte der Malerei.) 



TI'SIAS. [ORATORY.] \ 



TISSAPHERNES. [CVRUS THE YOUXGER.] 



TISSOT, SIMON ANDREW, an eminent Swiss phy- 

 sician, was born at Lausanne, in the canton de Vaud, in 

 1728. He studied first at Geneva, and then at Montpellier, 

 from 1746 to 1749, where he took his degree of Doctor of 

 Medicine. He then returned to Switzerland and settled at 

 Lausanne, where he joined to an extensive practice a con- 

 siderable degree of theoretical knowledge. His reputation 

 spread rapidly through Europe in consequence of his me- 

 dical publications, and caused him to be consulted from all 

 parts. He was also offered at various times several im 

 portant situations at different foreign courts and univer- 

 sities, all which he declined, and remained satisfied wilh 

 the respect and comfort which he enjoyed at home, and 

 with the office of professor of medicine at the college of 

 Lausanne. However, in 1780, he could not resist the warm 

 solicitations of the emperor Joseph II., who conferred on 

 him the professorship of clinical medicine at the university 

 of Pavia. Being thrown thus late in life into so difficult a 

 post, and being naturally of a modest and shy disposition, 

 he did not at first answer the expectations formed of him. 

 However there soon after broke out in the province an 

 epidemic bilious fever, as to the treatment of which the 

 physicians of the place were not agreed. On this occasion 

 the Count de Firmian, the celebrated minister under the 

 archduke, gave orders that Tissot's directions should be 

 followed, as he had treated a similar disorder with great 

 success in the canton of Le Valais in 1755. His system 

 was again successful, and the students not only celebrated 

 his triumph with ffites, but, wishing to render the memory 

 of it more durable, they caused a marble inscription, be- 

 ginning with the words Immortali Pra'<-rptt>ri, to be 

 placed under the portico of the school. After holding his 

 professorship for three years, Tissot obtained permission to 

 retire from office. During his stay in Italy he had made 

 use of the vacations to travel through the finest parts of 

 that country, and was everywhere received with the most 

 marked and flattering attention. Pope Pius VI. signified 

 his desire of seeing so estimable and eminent a man ; he 

 accordingly received him with much kindness, excused 

 him i as being a Protestant) from the ceremonial customary 

 at presentations at the Papal court, and made him a pre- 

 sent of a set of the gold medals struck during his pontifi- 

 cate. 



Having always lived economically and without any dis- 

 play, Tissot had saved while in Italy a sum of money suf- 

 ficient for the purchase of a country-seat, which he in- 

 tended to be the retreat of his old age. He had only 

 engaged himself in the Austrian service for a very limited 

 period ; he had now finished the medical education of a 

 favourite nephew ; and, lastly, as he himself with charac- 

 teristic playfulness expressed it, having received the title 

 of ' Immortal,' he thought it prudent not to run any risk 

 of descending from such a height, and of outliving (as he 

 might easily do) his apotheosis. He was succeeded in his 

 professorship at Pavia by the celebrated J. P. Frank, and 

 tlii-d unmarried, on the 15th of June, 1797, in his native 

 land, at the age of sixty-nine. A complete list of his works 

 : .en in the ' Biographic Mcdicak',' from which work 

 the abb ve account is taken : of these the following are the 

 interesting : ' Tentamen de Morbis ex Manustupra- 

 tione Ortis,' Louvain, 8vo., 1760; which was translated 

 into French, and has been frequently republished. 'Dis- 

 gertatio dr Uiliosix, sen Historia Epidemiae Lau- 



aanensis anni 1755,' Lausanne, 1758, 8vo. ' Avis au Peuple 

 l.anaanne, 1761, 12mo., which was translated 



into no loss than seven different languages, and in loss 

 i six years reached the tenth edition. It has since been 



frequently reprinted, and contributed more than any of his 

 other works to make the author's name known throughout 

 Europe. It served also as the model and foundation for 

 many similar popular works in more recent times. ' De 

 Valetudine Litteratorum,' Lausanne, 8vo., 1766, which was 

 translated into French, and frequently reprinted, and of 

 which the latest and best edition is that by F. G. Boisseau, 

 Paris, 1826, 18mo., with notes by the editor, and a 

 memoir of the author. ' Essai sur les Maladies des Gens du 

 Monde,' which has also gone through several editions. There 

 is a complete edition of his works by J. N. Hall6, in 11 

 vols. 8vo., Paris, 1811, with notes by the editor and a me- 

 moir of the author. Besides these original works Tissot 

 edited at Yyerdun, 1779, in three volumes 4to., the treatise 

 of Morgagni, 'DeSedibus et Causis Morborum per Ana- 

 tomen Indagatis,' to which he prefixed a history of the 

 Life and Works of the author. 



TISSUES, VEGETABLE. The various organs of plants, 

 as the leaves, flowers, roots, stem, &c., are composed of 

 certain ultimate structures, which are called elementary 

 organs or vegetable tissues. Most parts of a plant, when 

 cut into, present to the naked eye an almost perfectly ho- 

 mogeneous character ; and it is only by calling to our aid 

 the microscope that we can distinguish the various struc- 

 tures of which they are composed. On taking a leaf or a 

 portion of the stem of one of the higher plants, and sub- 

 mitting it to the microscope, it will be found to consist, 

 1, of a thin transparent homogeneous membrane, which is 

 arranged in the form of cells or cylindrical tubes; 2, of 

 fibres, which are arranged in a spiral form in the interior 

 of the cells or tubes ; and 3, a fluid of varying density, 

 filling the cells and existing between them, and containing 

 in it globules of various sizes and kinds. These parts 

 constitute what are known respectively as ' elementary 

 membrane,' ' elementary fibre,' and 'organic mucus.' Ele- 

 mentary membrane, and the fluid from which it is developed, 

 are the only two which are constantly present in all plants. 

 Fibre is only found in the higher forms of plants. 



The primary form in which organization appears is that 

 of a simple cell containing or surrounded by a fluid ; and 

 however complicated may be the forms which the tissues 

 of plants may assume, they mostly originate in this primi- 

 tive form. Some late researches on the development ot 

 tissues in animals seem to lead to the conclusion that, 

 some of these tissues are formed from a primitive fibre ; 

 and from analogy it has been supposed that the same may 

 occur in vegetable organization. Whether however the 

 coll or the fibre shall be determined to be the primitive 

 form of tissue in the animal kingdom, there can be little 

 doubt that the cell is so in the vegetable kingdom. 



The development of the cell itself is a subject of much 

 interest, and great light has been thrown on this obscure 

 department of physiology by the late researches of Dr. 

 Schleiden. It was long since observed by Robert Brown 

 that in the cells of the tissue of Orchidaceous plants there 

 was an opaque spot, or ' areo/a,' in the interior of the cell : 

 Schleiden, finding this spot very constant in the cells of 

 certain plants, concluded that it must have some important 

 relation to them, and submitted it to a very strict exami- 

 nation. He found that these bodies were the original 

 particles from whence the cells were formed ; hence he 

 called them cytoblasts. The best parts of the plant for 

 observing the phenomena to \yhich these bodies give 

 rise are, the large cell which exists between the embryo 

 and the membranes of the seed, and in which the albu- 

 men is subsequently deposited, the embryonal sac, and 

 the end of the pollen-tube, from which the embryo itself 

 is developed. In the gummy fluid that exists in these 

 parts in the process of growth a number of granules are 

 developed, rendering this transparent homogeneous fluid 

 opalescent, or almost opaque. It is among these granules, 

 which assume a brownish-yellow colour under the influence 

 of tincture of iodine, that the cytoblasts make their appear- 

 ance. Whilst in this state the cytoblasts increase con- 

 siderably in size, becoming larger than the granules of the 

 gum; and as soon as they have attained their full size, a, 

 delicate transparent vesicle rises upon their surface : this 

 is the young cell, which at first represents a very flat seg- 

 ment of a sphere, whose plane side is formed by the cvto- 

 blast, and the convex side by the young cell, which is 

 situated on it, somewhat like a watch-glass on a watch. 

 In its natural medium it is almost distinguished by this 

 circumstance alone, that the space between its convexity 



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