LUNGS, DISEASES OF THE. The highly organised structure of the lungs and the incessant exercise of their important function, frequently under noxious circumstances, render these organs perhaps the most liable to disease of any in the body. Exposure to damp and cold, sudden atmospherical changes and transitions of temperature, want of proper nourishment, inattention to personal clennlinese, and some of the mechanical employmnents in which the confined and heated atmosphere of workshops is impregnated with minute particles of foreign substances, such as steel, wool, &c., may be considered as amongst the chief excitiug causes of this e:cteusively prevailing class of diseases. The subject may be conveniently divided into those affections which are acute and rapid in their progress, and those in which their course is Blower and the changes of structure more gradually effected.
In inflammation of (i.e lungs (pneumonia peripueunionin) the air. cells and parenchymatous structure of the organ are the seat of the disease. This affection is generally preceded in a greater or less degree by shivering and such other febrile symptoms as commonly usher in any febrile attack. Soon afterwards pain and a sense of oppression are felt in the chest, with hurried respiration and a short dry cough. The pain is sometimes severe, sometimes it is described as of a dull and obscure kind and deeply seated. If the pleura, or investing membrane of the lungs, participate in the affection, it is geuerally severe. At first there is little expectoration, but this increases in the progress of the disease, and the sputa acquire a reddish or rusty colour from the admixture of small quantities of blood. They also possess an unusual viscidity and tenacity, sometimes to such a degree that the vessel into which they are received may be inverted without their falling out ; they also contain numerous minute bubbles of air, which are prevented from escaping by the consistence of the secretion.
If the disease continuo unchecked, the difficulty of breathing becomes much greater, and the respirations, which in the natural state are about 20 in a minute, increase in frequency to about 40 or 60.
Sometimes there is little cough throughout the disease, but most commonly it increases as the disease advances, and the sputa becomes more deeply tinged with blood. The features subsequently assume a livid appearance ; the breathing gets more oppressed ; expectoration is effected with difficulty; the powers of life fail, and the patient dies from the lungs being no longer able to carry on their function.
When a favourable change takes place in the course of the disease, either spontaneously, or from judicious medical treatment, it is generally attended by perspiration, the expectoration loses its rusty colour and unusual tenacity, the urine becomes turbid, and sometimes there is diarrInea. Andral and other authors are of opinion that improvement is most likely to take place at certain times—critical days. The diagnosis of this disease has received most important assistance from nuscultatiou, and in many instances it has been detected by its aid, where formerly it would have been overlooked. The assistance afforded by the auscultatory signs will perhaps be better understood if we defer them until we have spoken of the changes of structure in the lungs occasioned by inflammation.
In the early stage of pneumonia the inflamed part acquires an unnatural density mid heaviness from the unusual accumulation of blood in it, and if a portion of lung so ciretunstauced be examined after death, pressure with the finger on its surface leaves an indenta tion which is not fulled up, ns would, immediately be the case in a healthy state of the part. When it is cut into, n bloody frothy fluid exudes freely from it, mid the surfaces present rt deep blood-red colour, and if a portion be squeezed betwceu the finger and thumb a crackling noise is heard indicating the presence of air. In n more advnneed state, the lung is found still more dense, nrul does not crepitate when rulucezed, ',bowing that air is 110 longer admitted. Aa in this condition it somewhat resemblia liver, it has been termed the stage of Arpatisa lion. When the disease has proceeded still further, suppuration may be found to have taken place. Pits is then