412 MUCOUS MEMBRANES. 



ordinary mucus, of minor physiological importance, with which 

 the mucous membrane, even in its normal state, is coated. 

 We are familiar with "mucous catarrhs" in which mucus is 

 secreted in excessive quantity. Tliey chiefly affect such parts 

 of the tract as are distinguislied by their wealth in muciparous 

 glands, e.g. the pharynx, air-passages, stomach and large 

 intestine. We know, however, that the faculty of producing 

 mucous is not peculiar to the acinous glands ; but that mucous 

 metamorphosis of the protoplasm is to the epithelial cells of 

 mucous membranes, what horny transformation is to the cor- 

 puscular elements of the epidermis (cf. § 40) ; hence we are not 

 ■surprised to find mucous catarrh, and mucoid elements in the 

 catarrhal secretions, of mucous membranes which, like that of 

 the bladder, are destitute of glands. 



An over-production of " corpuscular " elements upon a 

 mucous surface, presupposes a degree of irritation more intense 

 than that which gives rise to the simple mucous variety of 

 catarrh. Here we must distinguish between epithelial and 

 PURULENT catarrh, according as epithelial cells or pus-corpuscles 

 predominate in the secretion. I say predominate ; since both 

 are usually present together. A catarrh exclusively epithelial 

 may be seen on the mucous lining of the tongue, the " fur " 

 being nothing more than an exuberant desquamation of pave- 

 ment epithelia, such as are proper to this region of the mucous 

 tract. With regard to the origin and secretion of these cells, I 

 refer the reader to the details given in § 83. There is no 

 reason to suppose that the epithelial cells which are produced in 

 excessive amount, originate according to other than the usual 

 laws ; from this point of A'iew therefore, epithelial catarrh may 

 hQ regarded as a simply hyperplastic process. 



But what are we to say when we find pus-corpuscles in the 

 catarrhal secretion, when the catarrh is purulent ? Are the pus- 

 cells also to be regarded as products of the subepithelial con- 

 nective tissue ? Against this view, which was formerly generally 

 received, it may be urged, that it is always possible, either by 

 scraping, or in vertical sections, to demonstrate an epithelium 

 which difters little, if at all, from the normal type, in mucous 

 membranes which are in a state of well-marked purulent 

 catarrh. Recent researches indeed, in which Remak^ BiM, and 

 myself have taken part, point to the conclusion that pus may be 



