RESPIRATION. 



293 



areolnr tissue, being accumulated at individual 

 spots, is important and worthy of great atten- 

 tion, on account of the facility with which it 

 interferes with the calibre of the tubes, 



Chronic inflammation of the bronchial mem- 

 brane gives rise, especially in parts abounding 

 in glands, to glandular hypertrophy, mucous 

 poll/pi, epithelial growths, sponyy and velvety 

 thickening, relaxation of the muscular and 

 fibrous elements, follicular ulceration, &c. 



The pathological conditions of the broncho- 

 pulmonary mucous membrane differ in no 

 respect from those of any other membrane of 

 this class. 



In plastic or exudative bronchitis are cha- 

 racterised by a morbid action of a croupous 

 nature. 



In bronchial croup the tubular exudations 

 from the larger bronchi present a calibre in- 

 versely proportional to their thickness, and 

 those thrown off from the finer ramifications 

 occur as solid cylinders. 



Asthmatic affections may either have their 

 exciting cause in the lungs or in the condition 

 of some remote organ. They partake of a 

 nervous and muscular character, and are 

 frequently caused by a collapse of a portion 

 of the lung. The collapsed part operates as 

 an excitor of the muscular spasm. 



English pathologists recognise the follow- 

 ing forms of disease proper to the parenchyma 

 of the lungs: Pneumonia, or inflammation 

 of the cell-tissue of the organ ; gangrene ; 

 hemorrhage; cedema ; emphysema; phthisis; 

 cancer. 



Inflammation of the vesicular tissue of the 

 lungs is marked by the exudation of the co- 

 loured elements of the blood. This fact was 

 once supposed to prove the absence of epi- 

 thelium in the air-cells. This inference is 

 erroneous. 



Inflammation of the lung is divided into 

 three stages, according to the consistency or 

 physical condition of the exuded product. 

 The first is that of engorgement ; the second 

 is that of hepatisation ; the third is that of 

 grey hepatisation. 



Gangrene of the lungs occurs under two 



O 



anatomical forms, the diffused and the cir- 

 cumscribed. 



Cancer of the lung, most commonly of the 

 encephaloid species, occurs in the forms of 

 secondary nodules and primary infiltration, 

 accompanied or not by tuberous formation 

 on either mediastinum about the main right 

 bronchus (Walsh). 



The anatomical changes which occur in the 

 lungs in phthisis are referrible to three main 

 stages, corresponding habitually to certain 

 varieties in the symptoms, and always to 

 modifications in the physical signs. The 

 first stage is that of deposition and induration; 

 the second that of softening; the third that 

 of excavation. 



The exact seat of pulmonary tubercle has 

 proved, from the dawn of pathology to the 

 present time, a controverted point. The 

 question is whether the deposit of the morbid 

 product occurs first on the free surface of the 



air-vessels into the substance of their walls, 

 or between them into a supposed inter- 

 vesicular tissue. From Morton and Bayle 

 to Rokitansky and Lcbert, advocates for each 

 of these "seats of election" have contended 

 in turn. The free or aerial surface of the 

 air-cells is now the commonly accepted si- 

 tuation of the tuberculous deposit. 



The nature of the tuberculous matter is 

 not less disputed ; witness the following defi- 

 nitions : 



Tubercle is a specific exudation (Ancell). 



Tubercle is a degraded condition of the 

 nutritive material (Dr. C. J. B. Williams). 



Tubercle is composed of the products of 

 inflammation (Reinhardt). 



Tubercle is composed of the dead-tissue 

 elements (Henle). 



Tubercles themselves consist of abnormal 

 epithelial cells (Dr. W. Addison). 



Tubercles are composed of metamorphosed 

 organised elements ; a metamorphosis co- 

 ordinate with the fatty and the waxy de- 

 generations (Virchow). 



Tubercle is a product secreted from the 

 blood by the epithelium lining the air-cells 

 (Schroeder Van der Kolk*). 



The mechanism of emphysema is still sub 

 judicc. Some authors, with Laennec, ex- 

 plain it on the supposition that the walls of 

 the air-vesicles yield under the force of the 

 air when the expiratory current is impeded. 

 Another class of writers attribute it to an 

 excess in the inspiratory force. Mr. Rainey 

 contends that the parietes of the air-cells 

 suffer a change of structure by fatty dege- 

 neration, and that this change stands to em- 

 physema in the relation of a causal condition. 

 Dr. Gairdner affirms that emphysema of one 

 portion of the lung cannot occur unless a 

 collapse has happened in another part. Em- 

 physema fills up pneumatically the space lost 

 by the collapse, and no more. The chest 

 can only be filled; it cannot be inflated 

 beyond a given inspiratory limit. The air- 

 passages of the emphysematous portions are 

 free, not obstructed. If already the cavity 

 of the thorax be uniformly filled, it is certain 

 that emphysema is rendered physically im- 

 possible. Emphysema is plenum counter- 

 balancing collapse a vacuum. 



It is yet by no means determined to what 

 extent, if at all, the shedding or desquamation 

 of the epithelium of the air-passages takes 

 place in disease. 



( Thomas Williams?) 



STOMACH AND INTESTINE. 



(Syn. Stomach, formerly Maw, Eng. ; J\I(igen, 

 Germ.; ffro/j.a.xoCi yaar^p, Gr. ; Stomachus, 

 Vcntncnhis, Lat. ; Stomaco, Ventricolo, Ita!. ; 

 Estomac, Fr. ; Efitomnco, Sp. ; Intestine or 

 bowel, formerly gut, tr'rpe, enlrail, Eng.; Dunn., 



* See British For. Med. Cliir. Rev., for January 

 April, July, 1853; in which Nos. respectively three 

 excellent articles by Paget, Jenncr, and Sieveking, 

 will be found. 



u 3 



