300 DISEASES OF THE NASAL CAVITIES. 



although, indeed, most cases of coryza do depend upon exposure to 

 cold, and particularly upon exposure of the feet. 



Next in frequence, local irritants cause catarrh of the nasal pas- 

 sages, such as the entrance of hot air, dust, acrid gases or foreign 

 bodies ; or the snuffing of tobacco by persons unaccustomed to it ; 

 likewise blows or shocks which the nose may encounter, and often re- 

 peated and violent blowing of the nose, etc. Nasal catarrh may also 

 be an accompaniment of other diseases, ulcers, outgrowths (Neubil- 

 dung), caries, necrosis of the nasal bones. Inflammation from neigh- 

 boring organs often spreads into the mucous membranes of the nose ; 

 thus, a very troublesome and intense coryza always accompanies a boil 

 of the upper lip, and an abscess of the gum of the superior incisors. 

 Nasal catarrh, too, is frequently a symptom of constitutional disease. 

 The coryza which accompanies measles and exanthematic typhus 

 belongs to this class, as do also the milder form of scarlatinous co- 

 ryza, the coryza of congenital syphilis (see syphilis, vol. ii.), and 

 probably also the nasal catarrh, which attacks a great number of per- 

 sons during the prevalence of the influenza-epidemics, forming one of 

 the symptoms of very general catarrh. In some respects, also, the 

 iodine coryza, which constitutes one of the chief symptoms of iodio 

 poisoning, comes in this category. 



The somewhat common opinion, that a cold in the head is conta- 

 gious, is contradicted by the experiments of JFriedrich, who could not 

 succeed hi implanting the disease upon the mucous membranes of 

 healthy persons by transferring to them secretions of persons suffering 

 from catarrh in its several stages. 



ANATOMICAL APPEARANCES. At the commencement of an acute 

 nasal catarrh, the capillaries of the nasal mucous membranes are sur- 

 charged with blood, the tissues are infiltrated, and the membrane, 

 swollen by hypersemia and oedema, gives out a colorless, thin, saline 

 secretion. At a later period, while the hyperaemia and swelling of the 

 mucous membrane diminish, the secretion becomes thicker and less 

 transparent, from a copious admixture of young cells. 



In chronic catarrh the nasal membrane is considerably swollen ; it 

 discharges a secretion, scanty in a few instances, but usually profuse 

 and purulent, from the number of young cells which it contains. This 

 often dries up within the nose into hard, dirty, dark-green crusts, and in 

 some persons it evinces a great tendency to putrefaction without any 

 assignable cause. 



In many instances chronic nasal catarrh produces catarrhal ulcers, 

 the cell-formation not confining itself to the surface, but spreading into 

 the substance of the mucous membrane. They remain superficial, as a 

 rule, but sometimes, particularly in scrofulous and cachectic subjects T 



