EPITHELIAL CARCINOMATA. 



199 



§ 166. Epithcliomata of the skin and mucous membranes, 

 save when they originate in warts or cauHHower excrescences, 

 (§ 148) always begin as flattened and indurated elevations of the 

 surface. They extend progressively both in depth and in super- 

 ficial area. -Should the growth have reached a certain maximum 

 of development at its place of origin, it breaks open at this point. 

 The surface, somewhat tuberculatcd from the first, grows rough ; 

 erosions, fissures, and holes appear in great numljcrs, and exude a 

 white, inodorous, pulpy fluid, mixed with pus. The tumoiu' 



Fig. tlo. 



Section tlirougli the growing edge of an epithelial cancer of the 

 skin. a. The fully-developed growth ; c^dmdcrs of epi- 

 thelial cells containing pearly nodules (concentric globes), 

 seen in longitudinal section ; h. An enlarged sebaceous 

 gland ; c. Commencing elongation of peg-shaped protru- 

 sions of the epidermis in an inward direction. ^ jj. 



next falls in at its centre ; a hollow is produced, which is hence- 

 forth masked, either by the dried secretions, or, when these are 

 removed, by the sloughy shreds of the original tissue. In this' 

 phase of its development, therefore, the epithelioma presents the 

 appearance of an ulcer with a hard base, and hard, raised edges. 

 At the periphery of the ulcer, we note the constant advance of 

 the infiltration into neighbouring parts ; in its indurated border, 

 we can studv the characters of its maturity ; while towards its 



