THE SKIN. 581 



traversing the cement-substance, the formerly so-called "thorns," become 

 thickened. The underlying papillae are slightly enlarged in all diameters, 

 partly owing to a dilatation and engorgement of their capillary blood-vessels, 

 partly through a peculiar change of the bundles of the connective tissue and 

 the bioplasson bodies between them. The latter look slightly enlarged, and 

 in many instances coarsely granular ; the former are partly transformed into 

 bioplasson. In other words, where before bundles built up by a glue-yielding 

 basis-substance were present, the reticulum of the living matter, before hidden 

 in the relatively solid basis-substance, becomes visible again through a lique- 

 faction or dissolution of this substance. No other proof of the presence of 

 an exudation in this stage can be obtained, except the liquefaction of the 

 basis-substance. This stage of inflammation is termed "papular." 



Next, in the middle of the papule, on one or on several spots, the exuda- 

 tion makes its appearance ; the outer or epidermal layer at no time partici- 

 pates in the morbid process. In some epithelia we notice an enlargement of 

 the meshes of the living reticulum ; the latter is first stretched, afterward torn 

 apart, the granules being suspended in the liquid exudation. Where epithelia 

 were present before, a small, irregular cavity is visible. If several such 

 cavities have formed in a papule through a continuously increased accumula- 

 tion of the exudation and destruction of the epithelia, the separating layers 

 of the epithelia become compressed and produce septa, traversing the cavities. 

 Such septa vary greatly both in number and width. The neighboring epithelia 

 have a coarsely granular appearance. Many of them have lost the inclosing 

 cement-substance, and are thus transformed into clusters, in which, through 

 a considerable increase of the living matter, new shining lumps of different 

 size appear, which are still in continuity with the neighboring reticulum 

 by means of delicate threads the so-called endogenous formation of new 

 elements. The result of this process is the formation of an irregular cavity 

 in the middle of the greatly widened rete mucosum, traversed by septa of 

 compressed epithelia, and filled with an exudation, in which there are sus- 

 pended numerous delicate granules, generally termed coagulated albumen, 

 and a varying amount of irregular threads in the form of a felt- work, the 

 coagulated fibrine. A few scanty plastids are also suspended in the exu- 

 dation, perhaps remnants of the destroyed epithelia, perhaps immigrated 

 inflammatory or colorless blood-corpuscles. 



In this condition of the rete mucosum, the underlying connective tissue 

 exhibits considerable changes. The papillae have disappeared, evidently 

 through the pressure from above. The transformation of the connective 

 tissue into bioplasson has advanced, in some instances, to such a degree that 

 the uppermost layers of the derma are replaced by numerous indifferent, or 

 medullary, or inflammatory corpuscles, as a rule, clustered together. All 

 these elements, however, are in an uninterrupted connection with each other 

 through delicate filaments of living matter, fully analogous to those of the 

 epithelia, and thus the inflamed tissue, though reduced into its medullary con- 

 dition, still represents a tissue. The stage of the disease in which the changes 

 just described had taken place is known as the vesicular stage of small-pox. 



Lastly, pus-corpuscles appear in the cavity within the rete mucosum. 

 The main mass of these doubtless arise from the epithelia traversing and 

 bbunding the cavity. Through the increase of living matter in the large num- 

 ber of epithelia, shining lumps appear, first homogeneous-looking, afterward 

 through the intermediate stage of vacuolation transformed into nucleated plas- 





