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nutrition, I may mention in the first place, as of most 

 importance, inheritance; then age, sex, physiological con- 

 stitution, errors of development and pathological processes, 

 and psychical influences. Of these I am more concerned, 

 on the present occasion, with inheritance, the influence of 

 which is so emphatic and unmistakable as to often render 

 all other possible causes as of no account. It should be 

 remembered that hereditary constitutional maladies may be 

 indiscriminately inherited from either parent, but that when 

 both parents have the power of transmitting the same con- 

 stitutional condition or anomaly, the transmission becomes 

 almost absolutely certain. Heredity is the rule ; non- 

 heredity the exception. The exception may be illustrated 

 by the following facts : The influence of an affected parent 

 may be neutralised or rendered dormant by that of the 

 other one : by atavism or reversional heredity a whole 

 generation may be passed over, the inherited influence 

 reappearing as potently as ever in the next : some members 

 of a generation may be affected, others spared, owing to the 

 influence of one parent being transmitted to certain mem- 

 bers, whilst that of the other is transmitted to others, or 

 that of fathers to sons, of mothers to daughters, or of 

 fathers to daughters, and of mothers to sons. As Immer- 

 mann says : " The parents need not always exhibit visible 

 signs of their constitutional vice at the moment of concep- 

 tion : a general disorder of nutrition which is latent in them 

 is as capable of being transmitted as one that is apparent. 

 The inherited vice often remains latent in the infant, and 

 does not show itself until a later period till the age at 

 which it showed itself in the parent. Hence, it follows that 

 age as well as sex may favour or oppose the influence of 

 heredity ; that it is more correct to speak of the constitu- 



