PLEURA 



4707 



PLINY 



small telescope. Legends state that the seven 

 stars are the daughters of Atlas and the nymph 

 Pleione, who were transformed into stars by 

 the gods and placed in the sky. There are 

 various versions of the legend. One states that 

 the seven committed suicide out of grief be- 

 cause of the death of their sisters, the Hyades. 

 Another states that the death of Atlas, who was 

 turned into a mountain at sight of the head of 

 Medusa, led to their suicide. The six visible 

 - are named Electra, Maia, Taygeta, Al- 

 rie, Celaeno, and Merope. The invisible 

 one, Sterope, is said to hide herself in shame 

 because she alone of the seven married a mor- 

 tal. 



The Pleiades may easily be recognized on 

 any clear night. They are situated in the neck 

 of Taurus, and are usually regarded as the cen- 

 tral constellation of the Milky Way. See map, 

 page 445. 



PLEURA, plu'ra, THE, from a Greek word, 

 pleura, meaning side or rib, is a double sac of 

 thin, watery (serous) membrane. The inner 

 bag, called the pulmonary pleura, covers the 

 lung; the other, the parietal pleura, lines the 

 cavity of the chest, the thorax. When in a 

 healthful condition the two sacs touch each 

 other, and a fluid, as in other serous mem- 

 branes, moistens them continually, so the mo- 

 tion of the lungs against the thorax in breathing 

 is smooth and painless. There are two pleura, 

 tin- right and left. They touch at the middle 

 of the sternum, or breastbone, and so form a 

 wall for the other organs of the chest. Inflam- 

 mation of the pleura causes the disease known 

 as pleurisy. See PLEURISY; MEMBRANES. 



PLEURISY, plu'risi, inflammation of the 

 serous membrane that lines the inside of the 

 t and covers the lungs (see PLEURA). In 

 1th, these two surfaces of the membrane, 

 being smooth and moist, glide over each other 

 with every breath we take, without any per- 

 tibk movement. When the pleura is in- 

 flamed the surfaces become dry and rough and 

 rub together with every breath, causing intense 

 pain in the side. Chills and fever, difficult 

 breathing and a short, dry cough are all charac- 

 teristic symptoms of an attack of pleurisy. In 

 a few hours a small quantity of fluid is poured 

 out in the pleural sac, which in favorable cases 

 ves pain and is absorbed. Sometimes, 

 however, the effusion is so large as to compress 

 the lung, and continued inflammation in such 

 cases may cause the development of malignant 

 fluid, resulting in serious com- 

 plications. Physicians usually distinguish these 



forms as dry pleurisy and pleurisy with effu- 

 sion. 



An attack of dry pleurisy is treated by rest 

 in bed, hot baths, the application of a mustard 

 plaster and strapping the chest to limit the 

 breathing movements. Pleurisy with effusion 

 sometimes requires the operation of tapping 

 the chest to draw off the fluid. In most cases 

 a physician should be called at once. The 

 malady is often the result of exposure to cold, 

 but sometimes it occurs as a complication of 

 pneumonia or tuberculosis. 



PLINY, plin'i, the family name of two dis- 

 tinguished Roman writers, uncle and nephew, 

 known respectively as the Elder and the 

 Younger. 



Pliny the Elder, whose name in Latin is writ- 

 ten GAIUS PLJNIUS SECUNDUS, was born in A. D. 

 23 and died in 79, during the famous eruption 

 of Mount Vesuvius. From Northern Italy, 

 where he was born, he went to Rome while 

 but a boy, and because he came of a wealthy 

 family received the best education the city 

 afforded. As a soldier in the wars with the 

 Germans he distinguished himself, but his at- 

 tempts to practice law were unsuccessful, and 

 he withdrew to his estates at Novum Comum. 

 In 71 he was in Spain as procurator, and on re- 

 turning to Rome two years later he adopted 

 his nephew, who became known as Pliny the 

 Younger. Under the Emperor Vespasian, 

 Pliny's personal friend, he received various of- 

 fices and commissions. Whether at home or 

 traveling from place to place, Pliny never 

 ceased his systematic studies, but read and took 

 notes constantly, and his fund of information 

 has been the marvel of later ages. In 79 he 

 was in command of the Roman fleet, close 

 enough to see the eruption of Vesuvius which 

 destroyed Pompeii and Herculaneum ; and anx- 

 ious to observe as closely as possible the effects, 

 he landed at Stabiae. There he met death from 

 the vapors following the eruption. His nephew 

 describes his death in two letters to Tacitus. 



Pliny wrote, in thirty-one books, a continua- 

 tion of an earlier history of Rome, and various 

 other works; but the only one which survives 

 is his Natural History. This was compiled from 

 the notes which he made from readings and ob- 

 servations, and includes not only botany and 

 zoology, but geography, astronomy and me- 

 teorology. It has no great scientific merit, but 

 contains much information on ancient life* and 

 ideas' which is not elsewhere available. 



Pliny the Younger (62- ? ), whose name in 

 full was GAIUS PLINIUS CAECIUUS SECUNDUS, 



