PUSTULE. — SMALL-POX. 



349* 



of a new horny lamina. The horny layer continues very thin 

 for a long time, and we know how easily a renewal of the flux 

 may rupture the delicate membrane and so re-establish the 

 disease as soon as it is cured. It is worth notice that in cases 

 of permanent recovery the deepest cells of the rete Malpighii 

 exhibit a striking tendency to become infiltrated with pigment 

 (fig. 110) ; this manifests itself to the naked eye as a brownish 

 staining, diffuse or circumscribed, of the affected patch of 

 skin. 



§ 295. — h. The second variety of exanthematic pustule — 

 the 2^ocJc — is undoubtedly the most interesting of all cutaneous 



Fig. 110. 





^^:: 



Vertical section through the skin after chronic eczema. 

 a. Horny lamina; b. Mucous layer of the epidermis; 

 c. Pigmented layer of columnar cells ; d. Papillary body ; 

 e. Cutis traversed by streaks of pigment. 



eruptions from a histological point of vie\^'. The pock is at one 

 period of its existence a simple pustule, but that is before it has 

 attained maturity ; moreover it arrives at this stage by so 

 peculiar a road, that it is entitled on both grounds to an 

 independent position. 



The pock originates as a papule on a very hypersemic base. 

 This proposition, which is repeated by all text-books, may be 

 allowed to pass unchallenged, if we choose to term every hard, 

 nodular elevation of the cutaneous surface a papule. But it 



