CROUPOUS INPLAMMATION. 425 



and so might readily be mistaken for the positive j^art of the 

 structure; the possibility of error can only be excluded by 

 staining the preparation with carmine. The cells are of variable 

 size ; their dimensions increase as they approach the surface ; at 

 the extreme periphery of the membrane they are nearly twice as 

 large as lymph-corpuscles ; farther inwards they become smaller, 

 the smallest ones lying immediately upon the mucous surface ; 

 here too, the degeneration is less marked ; they can hardly be 

 distinguished from the normal cells which are still embedded in 

 the parenchyma of the mucous membrane. This gradual transi- 

 tion naturally masks the boundary-line between the surface and 

 the false membrane, though it never quite obliterates it. It 

 proves most undeniably, however, that the false membrane is pro 

 duced by the secretion of young elements upon the irritated 

 mucous surface, followed by their gradual stiffening, sclerosis, 

 glassy swelling, or whatever term we may choose to apply to 

 their degeneration. Accordingly, the false membrane occupies 

 the precise position which belongs of right to the epithelium ; 

 the degeneration in question taking the place of the normal 

 evolution of epithelial elements. What becomes of the original 

 epithelial investment of the affected region? Has it been 

 simply shed, or does it, too, take part in the formation of the 

 false membrane ? E. Wagner has attempted to solve this pro- 

 blem in a recent and very valuable investigation, and has 

 raised the participation of the epithelium in the morbid pro- 

 cess to the rank of a certaintv. He describes a very sinofular 

 metamorphosis of the pavement-cells (fig. 1 23), in consequence 

 of which the protoplasm disappears at certain points, appa- 

 rently receding to certain branching lines, where it assumes 

 a homogeneous aspect, and refracts light more highly than 

 ordinary protoplasm. The nucleus disappears; the entire 

 cell being represented only by a network of great delicacy, 

 resembling the antlers of a stag in shape. I believe that I have 

 myself seen this metamorphosis — at least in its earlier stages — 

 along the edges of the false membranes ; but I cannot ascribe 

 to it any far-reaching significance as regards their development ; 

 the thin stratum of epithelium does not seem to me to possess 

 sufficient resources of its own for the construction of a false 

 membrane. But I am willing to let the future decide on the 

 precise range of Wagner^ s discovery. 



