180 CARCINOMATA. 



destructive and malignant growths. Now it has been, and still 

 is usual, to regard a certain morphological peculiarity, what is 

 known as the alveolar type of structure, as essential to the recog- 

 nition of " cancer." This means no more than that we look for 

 the essence of cancerous degeneration in the development of cir- 

 cumscribed deposits of cells, which burrow their way in certain 

 directions, and necessarily convert the residual parenchyma of 

 the organ which is undergoing destruction into a trabecular 

 framework or stroma, the form and size of whose meshes 

 (alveoli) are regulated by those of the cellular aggregates w^hicli 

 they include. It is obvious that this plan of structure is pecu- 

 liarly adapted for the accommodation of large multitudes of free 

 cells ; and such an adaptation w^e must regard (in conformity 

 with what was said in § 121) as the most powerful cause both of 

 the local growth of a tumour and of the infection of the entire 

 organism. This justifies the seemingly arbitrary selection of the 

 alveolar type of structure as the anatomical mark of cancer ; but 

 a new difficulty starts up when we come to reflect that the term 

 " carcinoma" will also have to include the alveolar sarcomata ; 

 tumours, in whose " interpenetration with cellular aggregates " 

 we preferred to see an analogy with the suppuration of inflamed 

 tissues. I accept this consequence as logically inevitable, and I 

 therefore range myself on the side of those who regard " carci- 

 noma" as a term essentially clinical, finding but an imperfect 

 anatomical expression in that alveolar type of structure with 

 wdiich it is invariably associated. 



§ 148. The vast majority of carcinomata originate primarily 

 either from the epithelium which covers the free surfaces of the 

 body, the skin and mucous membranes, or else from the secret- 

 ing glands. They depend upon an abnormal growth of the 

 epithelial tissue. We might go so far as to say that the process 

 which underlies all these carcinomata is an ingrowth of the 

 epithelium into the sub-epithelial stratum of connective tissue, 

 whether of the skin or of a mucous membrane, or into the inter- 

 stitial connective tissue of the orlands. The manner in which 

 this ingrowth takes place differs widely in diff'erent cases. The 

 general impression conveyed by carcinomatous destruction, e.g, 

 the appearances presented by a vertical section under a low 

 power, seems to justify the assumption that it consists in a 

 morbid imitation of that histological process w^hich precedes the 



