IV ORIGINAL CA USES OF INSANITY 201 



influence of peculiarly favourable conditions, reaches a higher 

 development ; in another, under unfavourable conditions, 

 leads to psychical degeneration. 



" Whether consanguinity in marriage^ is to be regarded as a 

 factor in hereditary degeneration must for the present remain 

 undecided. The experiments of breeders of animals, who, it 

 is true, breed only from perfect individuals, as well as the 

 pedigree of the Ptolemies, go to disprove it. It is possible 

 that it remains for a long time without effect, so long as the 

 pairing individuals continue free from degenerative tendencies. 

 If this is not the case, rapid degeneration soon occurs — 

 albinism, deaf muteness, idiocy, sterility. 



"Lastly, there can be no doubt that everything which debili- 

 tates the nervous system and the generative powers of the 

 parents, be it immaturity or too advanced old age, previous 

 debilitating diseases (typhus, syphilis), mercurial treatment, 

 alcoholic or sexual excesses, overwork, etc., may give rise to 

 neuropathic constitutions, and thereby indirectly to every 

 possible nervous disease in the descendants. 



" The importance of heredity in our province becomes 

 particularly clear when the fate of families afflicted 

 with psychical disease is followed through several genera- 

 tions." 



"A genealogical table, compiled from my own observations, 

 will exhibit this : — 



1 Darwin, EJien Blutsverwandter, German by v. d. Velde, 1876 ; Devay, Du 

 Danger des Mariages consanguins, Paris, 1857 ; Baiidin, Ann. d'Hyg., second 

 ser. xviii. p. 52 ; Mitchel, ibid. 1865 ; Allg. Zeitschr. f. Psych. 1850, p. 359. 

 According to Beauregard {Ann. d'Hyg. 1862, p. 226), from 17 marriages between 

 relations 95 children were born, of whom 24 were idiots, 1 deaf, 1 a dwarf, 37 

 entirely normal. 



2 Cf. the interesting tables of Bird, Allg. Zeitschr. f. Psych. 7, p. 227 ; Tagnet, 

 Ann. Med. Psych. July 1877; Doutrebente, ibid. September, November 1869, 

 {Schmidt's Jahrb. 145, p. 3). 



