200 EPITHELIAL CARCINOMATA. 



centrcj we mark tlie disintegration of the morbid growth, and 

 the phenomena of repair, wdiich are occasionally very distinct. 



In considering the development of this variety of cancer, it 

 is convenient to distinguish between its first beginnings and its 

 subsequent extension. Thin vertical sections through the raised 

 border of an epithelioma of the skin, are best adapted for the 

 more accurate determination of its point of origin (fig. 63.) Pro- 

 ceeding from without inwards in our examination of this section, 

 from c to a, the first indication we have of the beginnings of the 

 morbid growth, is a striking enlargement of the sebaceous glands 

 (c). These increase in length and breadth ; their cascal ends 

 becoming irregularly nodulated and clubbed. At the very edge 

 of the tumour (h) we have a colossal example of this change ; 

 and a dispassionate investigation leads us to conclude that the 

 tubuli of the swollen gland difi:er in no respect from the adjoin- 

 ing protrusions of the cancroid growth (a). This resemblance is 

 especially due to the fact that during the elongation and thicken- 

 ing of the fundus of the gland, its character as a secreting organ 

 is Avholly lost; we miss the central cavity and the oil-globules; we 

 can see nothing but closely aggregated epithelial cells, and these 

 of such dimensions as far exceed the normal standard of the 

 sebaceous epithelia. 



These considerations make it credible that epithelioma of the 

 skin may originate in the sebaceous glands ; but on the other 

 hand, we must not forget that this " origin from sebaceous 

 glands" must be regarded as only a part of the entire phe- 

 nomenon, which consists in a thorough dislocation of the houndary- 

 line (Grenzverrlickung) heticeen epithelium and connective tissue. 

 On the one hand, we owe to Thiersch* the account of an epithe- 

 lioma which sprang demonstrably from the sudoriparous glands ; 

 on the other, we may see in any and every epithelioma, that it is 

 not the glands alone which take part in the formation of the 

 cancroid protrusions. Club-shaped processes of epithelium burrow 

 into the underlying tissues from the deepest points of the epithe- 

 lial stratum, from those convexities of the rete Malpighii which 

 lie in the inter-papillary furrow^s ; and it is this phenomenon, 

 to which the elongation of the existing epithelial protrusions 

 {i.e. the glands) is quite subordinate, which stamps a common 



* Thiersch, Der Epithelialkreha. Leipzig, Eugelmanu, I860. 



