I I O THE CAUSATION OF DISEASE. 



again, under a cell-E- concerning the nature of which 

 I do not profess to know anything, a mature tissue takes 

 on a remotely ancestral form — a form, namely, that is met 

 with in the most lowly organisms, as, for example, the jelly- 

 fish ; and in this connection it is interesting to note the ten- 

 dency which the sarcomata show to undergo mucous degeneration. 

 In old age, again, the higher epithelial tissues perish at the 

 expense of those which are merely connecting : under the failing 

 supply of healthy blood, there is a reversion to a simpler tissue. 

 Let it ever be remembered that the human organism contains 

 the potentialities of countless ancestors, and that these poten- 

 tialities may, under fitting conditions of E, be converted into 

 actualities. 



In the Lancet, £so. XXII. vol. i. 1887, will be found an 

 interesting communication by Dr. Gresswell, on the " Origin 

 of Tumours by Reversion." This communication suggested the 

 following remarks from me, which I venture to quote here, 

 since they bear upon the present subject : — 



" I have been inclined, for some little time past, to regard certain 

 new formations as reversions, of limited patches of tissue, to an 

 ancestral type — notably, the enchondromata, myxomata, sarcomata, 

 and the new formation occurring in consequence of inflammation — 

 namely, granulation-tissue, including, of course, the granulomata. 

 It must not be forgotten that the reversion of which Dr. Gresswell 

 speaks is not the ordinary reversion which occurs during the embryo- 

 logical development of an organism, but the reversion of a fully 

 ■evolved and specialized tissue to one of remotely ancestral type. That 

 such a fully developed tissue may thus revert is a well-recognized fact. 

 Dr. Maudesley points out that during the cerebral disturbance which 

 heralds an attack of insanity, the moral faculty — viz., that mental 

 element which has been last acquired — is generally the first to go. 

 This shows a reversion of cerebral tissue to an ancestral type. It is 

 well to bear in mind that the tissues of a fully developed organism 

 have many potentialities which only need fitting opportunities to 

 display themselves. These consist in modifications of cell environ- 

 ment. A good example of such latent capacities is afforded by 

 disease, atrophy, or removal of the ovaries or testicles, when the 

 organism tends to take on certain character of the opposite sex. This 

 shows that each sex contains potentially certain actualities of the 

 ,other, and similarly the most highly specialized organism contains 



