PLESSIS-LES-TOURS 



PLEURISY 



237 



much shorter than in Ichthyosaurus (q.v.). In the 

 abdominal region the extremities of each pair of 

 ribs are connected below by the development of 

 the hasmal spine. The scapulae are of moderate 

 size and widely separated. The two pairs of limbs 

 correspond closely in structure. The humerus and 

 femur are comparatively short and distally much 

 expanded ; the radius and ulna, tibia and. fibula 

 are short and flat ; the ' hand ' and ' foot ' are long, 

 the phalangeals being increased in number beyond 

 the normal complement. The limbs were covered 

 with integument so as to form simple undivided 

 paddles, as in the turtle. Plesiosaurus was un- 

 doubtedly aquatic, and probably haunted the 

 shallow seas and estuaries of Mesozoic times. Its 

 remains have been met with frequently in a fine 

 state of preservation, some almost perfect skeletons 

 having been obtained from the Lias of England. 

 Several genera of Plesiosauridae have been deter- 

 mined. One of these, Cimoliosaurus, met with 



Plesiosaurus dolichodeirus. 



In the Jurassic and Cretaceous strata of Europe, 

 North and South America, and New Zealand, 

 attained a length of between 30 and 45 feet. Plio- 

 saums was another genus, with a shorter neck (the 

 vertebra; twelve in number) and a comparatively 

 larger head than Plesiosaurns. In this genus the 

 lower jaw was sometime* nearly 6 feet long. See 

 the Manual of Paloeontology, by Nicholson and 

 Lydekker (1889). 



Plessis-les-Tonrs. See TOURS, Louis XI. 



Plethon, GEORGIOS GEMISTOS, a Greek scholar, 

 was most probably a native of Constantinople, and 

 found employment in the Peloponnesus under the 

 'despots' Manuel and Theodore Palieologus. He was 

 sent as a deputy to the council held at Florence in 

 1439, and here, if he did little for the union of the 

 Eastern and Western Churches, he did much to 

 spread a taste for Plato. He returned to Constant- 

 inople, and died there about 1455. See vol. i. 

 of F. Schultze's Geschichte der Philosophic der 

 Renaissance (Jena, 1874). 



Pleth'ora ( Gr. , ' fullness ' ) designates a general 

 excess of blood in the system. It may arise either 

 from too much blood being made or from too little 

 being expended. The persons who become plethoric 

 are usually those in thorough health, who eat 

 heartily and digest readily, but who do not take 

 u flic ient bodily exercise, and do not duly attend 

 to the action of the excreting organs. With them 

 the process of blood-making is always on the 

 increase, and the vessels liecome more and more 

 tilled, as is seen in the red face, distended veins, 

 ami full pulse. The heart is excited and over- 

 worked, and hence palpitation, shortness of breath, 

 ami probably a sleepy feeling may arise ; but 

 these symptoms, instead of acting as a warning, 



too often cause the abandonment of all exercise, by 

 which the morbid condition is aggravated. The 

 state of plethora thus gradually induced may be 

 extreme without any functions materially failing, 

 and yet the subject is on the verge of some danger- 

 ous malady, such as apoplexy, or stmctural disease 

 of the heart or great vessels, or of the lungs, 

 kidneys, or liver. 



Pleurisy, or inflammation of the investing 

 membrane of the lung (pleura), is one of the most 

 serious diseases of the cliest. It is very often, but 

 by no means invariably, associated with inflamma- 

 tion of the substance of the lung, commonly known 

 as Pneumonia (q.v.). Pleurisy without pneumonia 

 is much more common than pneumonia without 

 pleurisy. When both are present, but pneumonia 

 preponderates, the correct term for the affection is 

 pleura-pneumonia, although it is frequently spoken 

 of simply as pneumonia, probably in consequence 

 of the remedies being applied mainly to it, as the 

 more important of the two elements 

 in the compound malady. 



The pleura being a serous membrane, 

 its inflammation is attended by the 

 same course of events as have been 

 already described in our remarks on 

 the two allied diseases, Pericarditis 

 and Peritonitis. The inflammation is 

 of the adhesive kind, and is accom- 

 panied by pain, and by the effusion of 

 serum, of fibrinbus exudation, or of 

 pus into the pleural cavity. In the 

 last case it is called empyenia. In 

 consequence of the anatomical rela- 

 tions of the pleura one part of the 

 membrane (the parietal) lining the 

 firm walls of the chest, while the 

 other part (the visceral) envelops the 

 soft and compressible lung, and these 

 opposed surfaces being freely mov- 

 able on one another it follows that 

 different effects may be produced by its 

 For example, the visceral layer 



very 



inflammation. 



may be glued to the parietal layer, so as to prevent 

 all gliding movement between them, and to 

 obliterate the pleural cavity (similarly to what 

 often happens in Pericarditis, q.v.); or the two 

 surfaces which are naturally in contact may be 

 abnormally separated by an effusion of serum 

 between them ; or, from a combination of these 

 results, the opposite surfaces of the pleurae may be 

 abnormally united at some points, and abnormally 

 separated at others. 



The general symptoms of pleurisy are rigors, 

 pain in the side, fever, difficulty and rapidity of 

 breathing, cough, and an impossibility of assum- 

 ing certain positions ; and of these the most 

 marked is the pain or stitch in the side, the Point 

 de cote of the French writers. The pain, often 

 very severe, and often limited to one small spot, 

 is usually at the lower part of the affected side ; 

 but is occasionally felt in other parts as in the 

 shoulders, in the hollow of the armpit, beneath the 

 collar-bone, along the breast-bone, even in the 

 loins, simulating lumbago ; or, in the abdomen, so 

 as to suggest peritonitis or hepatitis. In some 

 cases it is altogether absent. The pain is increased 

 by percussion, by pressure between the ribs, by a 

 deep inspiration, by cough, &c. ; and the patient is 

 often observed never to draw more than a short 

 and imperfect inspiration. Cough is not invariably 

 present, although it is an ordinary symptom. It 

 is small, suppressed as far as possible by the 

 patient, and is either dry or accompanied by 

 the expectoration of slight catarrh. If much 

 frothy mucus is brought up it is a sign that 

 Bronchitis (q.v.) is also present, and the appear- 

 ance of rust-coloured sputa indicates the co-exist- 



