CELL 



1247 



CELLULOSE 



penances which, as a monk, he had imposed 

 upon himself, and he had founded a monastic 

 Order known as the Celestines. One of his 

 first acts was to issue a decree declaring that 

 any Pope had the right to abdicate, and in 

 December of the same year in which he was 

 elected he took advantage of this right and 

 resigned his high office. His reason was that 

 he wished to return to his devotions and 

 severities. Boniface VIII, his successor, feared 

 that a strong clerical party might grow up 

 about Celestine, so he had the latter placed 

 in prison, where he died. 



CELL, sel, in biology the "start in life" of 

 every living thing the unit of structure. Not 

 much more than one-thousandth of an inch 

 in diameter, a cell is a soft mass of living, 

 jelly-like matter, albuminous, like the white 

 of an egg. This is called the protoplasm. In 

 it, as a central organ, is a roundish structure, 

 like the yolk of an egg, called the nucleus.. The 

 nucleus is generally more solid than the rest 

 and sometimes has within it a smaller body 

 called the nucleolus, and all this is usually 

 surrounded by a cell-wall. The protoplasm 

 possesses life-giving properties ; the duty of the 

 nucleus is to govern the reproduction of the 

 cells. The cell multiplies by the division of 

 the whole cell into two. This process begins 

 at the nucleus, when the cell reaches a certain 

 size. Then the two parts grow to the size of 

 the first, and each repeats the process. This 

 is continued, cell on cell, until there results 

 the completed animal or plant. The lowest 

 forms of plants or animals, however, are always 

 a single cell (see PROTOPLASM). 



Cells, singly, are nearly spherical in outline, 

 but when pressed by other cells, they may 

 take on modified forms spindle-shaped, cylin- 

 drical, star-shaped, or they may appear as 

 polygons. 



CELLINI, chelle'ne, BENVENUTO (1500- 

 1571), the most distinguished goldsmith of the 

 Italian Renaissance, famed also as a sculptor, 

 engraver and writer. In his youth he began 

 to study the art of the goldsmith in his native 

 city of Florence, but was driven out of that 

 place as the result of a duel. Because he was 

 quick-tempered and quarrelsome he had to 

 move frequently, so he lived at various times 

 in Rome, Florence and other Italian cities, and 

 at one time was in France. His whole life 

 was a series of adventures. 



Under the patronage of Pope Clement VII, 

 Cellini became the greatest worker in metals 

 of his time. Later he was invited to the court 



of Francis I of France, and for that ruler 

 modeled the famous bronze figure, Nymph 

 of Fontainebleau, now in the Louvre. The best 

 example of his work as a sculptor is the bronze 

 statue of Perseus with the Head of Medusa, 

 a gruesome subject, which still adorns one of 

 the museums of Florence. Richness of decora- 

 tion and elaboration of detail characterize 

 nearly all of his productions, and these quali- 

 ties give to his work as a goldsmith marvelous 

 beauty. His famous Autobiography, begun 

 in his fifty-ninth year, is one of the master- 

 pieces of the world's literature. 



CELLULOID, sel'uloid, an attractive artifi- 

 cial substance extensively used as a substitute 

 for ivory, bone, hard rubber and coral. Having 

 such a close resemblance to these in hardness, 

 elasticity and texture, sometimes only experts 

 can detect it. Celluloid is composed of cellu- 

 lose, or vegetable fibrine, reduced by acids to 

 a substance resembling soluble cotton (see 

 GUNCOTTON); camphor is then added, and the 

 compound is molded by heat and pressure to 

 any desired shape. The manufacture of this 

 much-used substance is simple and interesting, 

 but sometimes injurious to the workmen, 

 through the acids used. The finished product 

 is not as safe as the things it resembles, for 

 the touch of a lighted match or a spark will 

 set it aflame. It explodes with a flash, like 

 gunpowder. Celluloid is used chiefly for but- 

 tons, handles for knives, forks and umbrellas, 

 billiard balls, backs of brushes, piano keys, 

 napkin rings, opera-glass frames, pipe-stems, 

 films for cameras and other small articles. It 

 can be variously colored. 



CELLULOSE, sel'yulohs, a substance found 

 in all plants except a few of the lowest kinds. 

 It forms the walls of the plant cells which 

 contain the living protoplasm. Cotton fibers 

 are composed almost entirely of cellulose, and 

 so are hornets' nests. It is also abundant in 

 flax fibers (and therefore in linen), and in 

 straw. Wood is largely cellulose, and the wood 

 pulp used in making cheap white paper is 

 nearly pure cellulose. 



Cellulose contains the same proportions of 

 its elements, carbon, hydrogen and oxygen, as 

 does starch. Like starch, also, it can be con- 

 verted into the sugar glucose by treatment 

 with sulphuric acid. It is classed among the 

 carbohydrates. Cellulose swells when wet, and 

 that prepared from corn pith is sometimes 

 used as a lining in warships to prevent leakage 

 when a shell pierces the side of the vessel. It 

 will not dissolve in hot water (as starch does), 



