THE CAUSATION OF DISEASE. 93 



other cells possess an obvious, discoverable structure, and such 

 being the case, it is impossible to trace the steps of their 

 evolution in any detail, and equally impossible to study the 

 reverse process with any minuteness. But what little we know 

 of the evolution and dissolution of such cells fully accords with 

 the conclusion we have reached ; and could we trace accurately 

 the several phases in the evolution of, say, a liver-cell — (and 

 the process is infinitely more complex than at first sight appears, 

 for, as I have already insisted, every active cell in the body has 

 a highly complex structure, and therefore a highly complex 

 evolution) — all analogy leads us to conclude that we should find 

 the pathological dissolution in very large measure an inverted 

 evolution. 



Hitherto I have spoken only of structural dissolution ; func- 

 tional dissolution has not been mentioned. It should, however, 

 be remembered that function is dependent upon structure : the 

 two, therefore, must stand or fall together. A careful study of 

 the perverted functions of disease and the order of their appear- 

 ance fully bears out the conclusion we have already reached. 

 Indeed, we have in such a study a far more accurate test of its 

 truth, for not only are we able to study the functional changes 

 from day to day, and even from moment to moment — a thing 

 manifestly impossible in the case of internal structural changes 

 — but we have in functional change a far more delicate test of 

 dissolution, seeing that a structural change which is quite 

 outside the reach of microscopic observation is capable of pro- 

 ducing very obvious functional alteration. A large chapter 

 might be written on Dissolution in Disease as manifested by 

 altered function, but there is no need to pursue this subject 

 further. 



lb. We have now to consider the influence of age upon char- 

 acters acquired by the individual himself. The second of the 

 above propositions affirms that ' ' characters acquired by the 

 individual himself tend to disappear in the inverse order of their 

 acquisition." The truth of this proposition is forcibly shown by a 

 study of human nature ; the longer a habit is indulged in, the 

 more difficult it is to shake it off. The latest acquisitions are 

 certainly the most fleeting, and this fleeting tendency of recent 

 acquisitions becomes more and more pronounced as life advances, 



