CATAREH, 



413 



produced on mucous membranes by cndogenoLis proliferation of 

 the surface epitheb'a. I have ah^eady described this mode of 

 origin in § 68. As regards the exact point where it is produced, 

 our only guide is the arrangement of the brood-cells, as seen 

 in vertical sections. Fig. 121 represents very accurately the 

 mutual relation of j^arts as seen in the ocular conjunctiva. The 

 mother-cells appear m situ, in the outermost layer of the epithe- 

 lial stratum ; below and on each side of them are epithelium- 

 cells, some normal, others which have already entered upoii 

 morbid chano-e ; towards the free surface we note the liberation 

 of pus-corpuscles, and the catarrhal secretion. 



This does not prove that all the pus-corpuscles contained in 

 the catarrhal flux, or that the pus-corpuscles in al! cases of 



Fic. !21. 



Purulent catarrh of tlie conjunctiva, a. Epithelium, h. Con- 

 nective-tissue stratum of the mucosa. 



catarrh, originate in this wise. On the contrary, if we reflect 

 that all young cells have the power of spontaneous locomotion, 

 and that the strong current of transuding fluid ma}- help, but 

 cannot hinder them in their migration, we cannot believe it 

 otherwise than possible, nay, even highly probable, that the 

 elements of the subepithelial embryonic tissue, to which allusion 

 has been already made, penetrate outward between the epithe- 

 lial cells, and so come to be set free. 



§ 353. Mucus and cells are products of the mucous mem- 

 brane ; they represent the increased amount of pabulum which 

 has been supplied to it, after it has undergone a certain elabora- 

 tion into secondary products. The case is different in many 

 catarrhal disorders of the gastro-intestinal tract. The stools of 



