354 MOHBID ANATOMY OF THE SKIN. 



description. Bdrensprung\s exudation is not sometliing amor- 

 phous — not coagulated albumen or fibrin; it is made up of 

 corpuscular elements — of pus-cells. We must recollect that even 

 in the catarrhal variety of suppm'ation, the papillary body was 

 abundantly permeated by young cells, some portion of which 

 emigrated and were thrown off. In the present case, this in- 

 filtration is excessive in amount; the cells accumulate in such 

 enormous numbers in the interior of the papillae, that they not 

 only mask, but compress, and so cause atrophy of all the other 

 structures, the connective-tissue fibres, the vessels and the nerves. 

 The blood cannot gain access to the infiltrated part ; hence its pallor. 

 The annexed drawing (fig. 112) shows this state of things tolerably 

 well. The vessels have been injected with gelatine and carmine. 



^ - _ - ^^^ , JM 







Diphtheritic pock. a. The normal skin surrounding it, which 

 is successfully injected. For further details see text. y^. 



Wherever the blood failed to penetrate during life, the injection 

 lias also failed to enter ; so that to right and left of the pock vre 

 see the capillary loops of the papilla well filled (« a), while the 

 pock itself contains no trace of them. It looks as if a semi- 

 circular piece of the cutis with its papilljB had been cut out of 

 the capillary netvv'ork. The whole of this portion is infiltrated 

 with pus- corpuscles in the way described above, and may be 

 regarded as already dead: the only question is how long the 

 fibres of the connective tissue, and the obliterated vessels which 

 it contains, and wliich connect it with the neighbouring parts, 

 will resist disintegration. They last longer in adults than in 

 young people. In the former case an adherent slough is formed in 

 the cutis ; in the latter, the infiltrated part soon melts into pus ; 

 this dries into a crust; in either case however a superficial 

 defect of the cutis remains — an ulcer — which heals by the second 

 intention, and leaves a permanent scai*. 



