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diathesis, and hereditary predisposition yet each child 

 preserves its own individuality by reason of the differentiation 

 produced by natural variability, to which every organic being 

 is subjected, in addition to heredity. Remembering that 

 each one of us has inherited certain peculiarities physio- 

 logical, psychological and pathological which we, in turn, 

 shall pass on to our descendants, I thus sought to prove the 

 reason why every individual differs in these respects from 

 every other, and why those peculiarities which distinguish 

 us from one another in health should also tend to modify or 

 intensify our relative proneness to certain morbid affections, 

 by the neutralisation or development of the morbid suscep- 

 tibilities or predispositions which have been transmitted to us. 

 Defining diseases, in the abstract, as not entities, but mere 

 groups of modifications of structures already in existence, 

 and of actions always progressing in a vital system in fact 

 particular conditions of the living body, new phases of its 

 vital manifestations, whether of the nature of functional 

 derangement or organic or textural degeneracy I was led 

 to conclude that the differentiation of individuals concerns 

 not only their physical nature and functions, their mental 

 qualities and moral character, but also their morbid 

 processes, whether functional or organic. In other words, 

 as the physiological and psychological nature of every 

 individual inherited and acquired differs from that of every 

 other, so too must every individual differ from every other as 

 to his pathological predispositions. Thus, whether we con- 

 sider man physiologically, psychologically, or pathologically, 

 we find the potency of heredity in his every aspect, and so 

 far as this influence extends there is an exact parallelism 

 between physiology, psychology, and pathology; they are, 

 in fact, names denoting man's organism and dynamism in 



