346 THE CAUSATION OF DISEASE. 



growth is derived from a multiplication of cells transported 

 from the primary tumour. Now, if this is true of one form 

 of carcinoma, why may it not also be true of the others, and, 

 indeed, of the secondary sarcomata likewise ? When the carci- 

 noma is reproduced in a tissue containing no epithelia, these 

 cells are probably derived solely from the multiplication of trans- 

 ported cells; but when the secondary carcinoma occurs in a 

 suitable epithelial tissue, the growth may be both by a multi- 

 plication of transported cells and of the normal epithelia of the 

 part. Such a twofold cell-origin is possible with all the sarco- 

 mata, for connective-tissue elements everywhere abound. 



How comes it that a tissue, hitherto normal, suddenly takes 

 on malignant growth ? * The cause must, as we have seen, 

 depend either upon — (i) an innate tendency of the tissue 

 primarily affected to undergo the malignant change inde- 

 pendently of a peculiar E ; (2) upon a distinctly peculiar E ; 

 or (3, and finally), upon abnormal tissue tendency combined 

 with peculiar cell-E. 



Is malignant disease due to an innate tendency on the part 

 of the tissue primarily affected to become malignant, in- 

 dependently of a peculiar cell-E ? Is the process analogous, 

 in fact, to the differentiation of tissue which occurs in the pro- 

 cess of development, a differentiation which certainly takes place 

 independently of distinctly peculiar E ? I say " distinctly 

 peculiar E," for doubtless the nature of individual cell-E plays 

 an important part in development. This fact is sufficiently 

 attested by a study of the laws of correlation, for if one particular 

 part be peculiarly affected in development, others are sym- 

 pathetically influenced, doubtless through the influence of one 

 tissue on the cell environment of others. Sir James Paget, in 

 his clinical lectures, evidently assumes such an innate origin, an 

 origin essentially through S and not through E. For he 

 argues thus : — Some individuals exhibit a tendency to super- 



* I say suddenly, for although Hutchinson has spoken of a pre-cancerous 

 stage — an inflammatory state preceding the actual cancerous change — it must 

 be conceded that there is by no means proof that this always occurs ; malig- 

 nant change may, beyond all doubt, be suddenly set up in a healthy tissue, 

 and this practically always happens in the case of the secondary growths. 



