106 PROCEEDINGS OF THE AMERICAN ACADEMY 



If these tliree suicides had been brothers and sistei's, their case would 

 have been put down as a strong instance of family insanity. Then 

 may not the repetition of suicide or other insane acts by membei's of 

 the same family be the result of this sympathetic propensity, or blind 

 imitativeness, roused into keener action by the example being set near 

 home, rather than the result of inherited mental disease ? If so, how 

 forcible is the lesson that we ought in every way to discourage and dis- 

 prove this doctrine of the hereditability of insanity ! Other cases are 

 not wanting. One was reported to the Paris Academy of Medicine, 

 that, a soldier at the Hotel des Invalids having hanged himself on a 

 post, his example was soon followed by twelve other invalids, and only 

 by removing the fatal post was the suicidal epidemic at last arrested. 



Thus far we have treated only of insanity. But the question is a 

 broader one. Do any peculiarities of mental or bodily organization, 

 appearing for the first time in one generation, tend to perpetuate them- 

 selves by the law of hei-editary descent ? Besides the specijic traits, 

 which every animal has in common with the species to which it belongs, 

 it has also individual traits or peculiarities, always prominent enough 

 to enable us easily to distinguish every individual from its fellows of the 

 same kind, even if they are the offspring of the same parents, and some- 

 times so strongly marked as to deserve the name of monstrosity or dis- 

 ease. Does nature tend to perpetuate or efface this distinction between 

 specific and individual traits ? The question is one of great importance 

 and the highest generality, affecting the basis of zoological science. If 

 this distinction is feebly marked and transitory, then there is no fixed 

 system or plan in the animal kingdom, and nothing for science to do 

 except to chronicle a succession of fleeting peculiarities and shifting 

 boundaries. If, on the other hand, the distinction is bi"oad and stable, if 

 what Blumenbach calls the nisus formativus necessarily tends to per- 

 petuate the species by restricting the law of hereditary transmission to 

 the specific traits, and excluding it from the individual peculiarities, 

 then the dominion of law, the unchangeable purposes of the Creator, 

 extend alike over the inorganic and the organic kingdoms, and nature 

 becomes one consistent, permanent, and intelligible whole. Undoubtedly 

 apparent exceptions occur, through a complexity of circumstances which 

 science cannot always unravel. Sometimes a specific trait is wanting, 

 and the result is a monstrosity, a lusus nalurce. ; but nature takes care 

 to kill out such monsters, usually in the first generation. Sometimes an 

 individual peculiarity of the parent, not so strongly marked as to deserve 



