482 THE RESPIRATORY SYSTEM. 



points of lodgment of tubercle bacilli, which have been gathered from 

 the pulmonary air spaces from the pharynx or elsewhere. 1 



The Lungs. 



Malformations. 



One or both lungs may be wanting or only partially developed. One lung is some- 

 times converted into a number of sacs formed of dilated bronchi, while the lung paren- 

 chyma is undeveloped. 



The lobes may be subdivided by deep fissures, accessory lobes may be present, or 

 an accessory lung may be present. An accessory lung in the abdominal cavity has been 

 described. 2 There may be with absence of part of the wall of the thorax hernia of the 

 lung. There may be transposition of the lungs, with similar changes in the position of 

 the heart and the abdominal viscera. 



INJURIES PERFORATIONS. 



Severe contusions of the thorax may produce rupture of the lungs, 

 with extravasations of blood into the pleural cavities. 



The lungs may be wounded by a fractured rib and by penetrating 

 weapons and projectiles. Such injuries often lead to bleeding into the 

 lung tissue followed by inflammatory changes. The lungs, however, 

 exhibit a considerable degree of tolerance for such injuries. 



Collections of pus in the pleural cavities, the mediastinum, the liver, 

 the spleen, the kidneys, and the peritonal cavity may perforate the lungs. 

 See also Hydropneumothorax. 



DISTURBANCES OF CIRCULATION. 



Anaemia. The lungs may be anaemic in connection with a general 

 anaemia of the body ; or from compression of a part or a whole organ, as 

 by pleural exudates, tumors, or new-formed fibrous tissue ; from occlu- 

 sions of blood-vessels or in atrophy of these in emphysema. 



HYPER^MIA AND (EDEMA. 



Hyperaemia may occur as the result of the inspiration of irritating 

 gases ; from the presence of toxic substances in the blood ; in early phases 

 of inflammation, or as the result of such an occlusion of vessels in one 

 part as causes its accumulation in another. 



On the other hand, hyperseinia of the lung is often due either to some 



1 Consult for summary of lesions of bronchial lymph-nodes Hall, Philadelphia Medical 

 Journal, December 1st, 1900, bibliography. See also concerning tuberculosis reference 

 JSorthrup and Bovaird, p. 398. See also statistics of Hand, Phila. Path. Soc., March, 

 1903. For an excellent resume concerning normal and pathological tracheal and bron- 

 chial lymph-nodes, see Mar/an in Bouchard and Brissaud's "Traite de Medecine," t. 

 vii., p! 525; also Zuber in Graucher, Comby, and Marfan's "Traite des Maladies de 

 1'Enfance," t. iv., p. 235. 



2 Consult Vogel, Virch. Arch., Bd. civ., p. 235, 1899, bibliography. 



