198 Heredity. 



A peculiar conformation of certain organs of sense, or a total 

 lack of them, are facts at once both of physiological and psych- 

 ological spontaneity. There are some persons whose eyes are unable 

 to discern some given colour blue, red, yellow, etc. Others are 

 born blind of parents possessed of perfect vision. Deaf-muteness 

 in many cases cannot be explained by anything in the parents. 

 Physicians cite many examples of families where the parents both 

 hear and speak very well, while their children are all born deaf 

 and dumb. Finally, the taste and the smell are sometimes struck 

 with anaesthesia, or complete insensibility, which cannot be ex- 

 plained by hereditary transmission. 



We will, in conclusion, glance at psychological idiosyncrasies, 

 and exceptional mental facts. Psychology, even as physiology, 

 has its rare cases, but unfortunately not so much pains have been 

 taken to note and describe them. Not to speak of insanity, 

 idiocy, or hallucination, which may occur, apparently at least, 

 without visible antecedent in the progenitors, there are some 

 purely moral states which are met with in a certain class of 

 criminals murderers, robbers, and incendiaries which, if we 

 renounce all prejudices and preconceived opinions, can only be 

 regarded as psychological accidents, more painful and not less in- 

 curable than those of deaf-muteness and blindness. We have given 

 sundry instances of these anomalies, and of their heredity ; but 

 they also frequently occur in the shape of isolated and nontrans- 

 mitted cases of moral monstrosity. These creatures, as Dr. Lucas 

 says, partake only of the form of man; there is in their blood 

 somewhat of the tiger and of the brute : they are innocently criminal, 

 and sometimes are capable of every crime. l 



IL 



Having shown by facts of every kind that there exist grave 

 exceptions to the law of heredity, we have now to explain them. 

 As we have seen, it is perfectly clear and unquestionable that 

 heredity is the law ; that this cannot be doubted ; and that even 

 in those cases which we qualify as exceptions, the exception is 



1 See several instances of moral monstrosity in the work of Dr. Despine 

 already quoted, vols. ii. and iii. 



