348 



THE PRINCIPLES OF HEREDITY 



538. Probably of all practical problems of heredity, that 

 of insanity presents the most menacing aspect. " Insane 

 persons have multiplied a hundredfold with civilization to 

 such an extent that where a few years ago one madman was 

 enough, now 500 are needed. In the United States, while 

 the population doubled in a little more than thirty years, 

 the insane increased sixfold, so that in the last decade the 

 increase in population was 30 per cent. ; and that of the in- 

 sane was 155 per cent. In France there were 131*1 insane 

 per 100,000 inhabitants in 1883, 133 in 1884, 136 in 1888. 

 These figures indicate that the number of the insane is larger 

 in most civilized countries, and is increasing every year." 1 

 " There is now one officially known lunatic to 301 '32 indi- 

 viduals of the general population, as against one to 335 nine 

 years ago, and one to 536 in 1859." 2 " From 1st January 

 1858 to 1st January 1902, the total number of lunatics 

 officially known to the Board . . . has increased from 5,824 

 to 16,288, showing an increase of 10,464. . . . Since 1858 

 the number of lunatics under the protection of the Board 

 has increased 180 per cent." 3 



540. The following are the figures for Ireland : 4 



As in the case of difficult parturition, many explanations 

 have been offered of the increase of insanity. Parental 

 disease and alcoholism have been thought to explain it in 

 part. But the phenomena of adaptation, the falling death- 

 rate, and the lengthened average duration of life indicate 

 clearly that this explanation is not valid. The growing stress 

 of modern life has been thought to explain it. But, while 

 it is possible that certain classes live under conditions of 

 greater strain, it is very doubtful whether the people at 



1 Lombroso. 



2 Fifty-fourth Report of the Commissioners in Lunacy, 1901, England 

 and Wales. 



3 Op. cit., Scotland. 



4 Macpherson, Edinburgh Medical Journal, May 1903, p. 398. 



