TABLE XXIII. ------------------------------------------------------------------------------- | |Consanguinity of | | | Parents | Percentages | |--------------------------------------------- | | | Not | Not | | Not | Not Cause of Blindness. |Total.|Cousins|cousins|stated|Cousins|cousins|stated ------------------------------------------------------------------------------- Total |64,763| 2,527|53,980 | 8,256| 3.9 | 83.4 | 12.7 ------------------------------------------------------------------------------- Opacity of the eye |33,930| 1,000|28,797 | 4,133| 2.9 | 84.9 | 12.2 ------------------------------------------------------------------------------- a. Causes affecting cornea|11,380| 444|10,016 | 920| 3.9 | 88.0 | 8.1 (1) Measles | 1,451| 73| 1,267 | 111| 5.0 | 87.4 | 7.6 (2) Scrofula | 1,165| 71| 1,026 | 68| 6.1 | 88.1 | 5.8 b. Causes affecting iris | 1,307| 33| 1,093 | 181| 2.5 | 83.6 | 13.9 c. Causes affecting lens |11,769| 228| 9,467 | 2,074| 1.9 | 80.4 | 17.7 d. Other causes | 9,474| 235| 8,221 | 1,018| 2.5 | 86.8 | 10.7 ------------------------------------------------------------------------------- Nervous apparatus affected| 7,944| 276| 6,980 | 688| 3.5 | 87.8 | 8.7 ------------------------------------------------------------------------------- Unclassified |14,885| 938|12,463 | 1,484| 6.3 | 83.7 | 10.0 ------------------------------------------------------------------------------- (1) Congenital | 4,728| 632| 3,666 | 430|13.4 | 77.5 | 9.1 (2) Other causes |10,157| 306| 8,797 | 1,054| 3.0 | 86.6 | 10.4 ------------------------------------------------------------------------------- Unknown | 8,004| 313| 5,740 | 1,951| 3.9 | 71.7 | 24.4 ------------------------------------------------------------------------------- To quote from the Report: The only specific causes, other than congenital, to which is due a greater proportion of the total cases of blindness among those whose parents were cousins than among those whose parents were not related, are: Catarrh (parents cousins 28.1, parents not cousins 8.7 per 1,000), scarlet fever (parents cousins 10.7, parents not cousins 10.1 per 1,000), scrofula (parents cousins 28.9, parents not cousins 19 per 1,000), and measles (parents cousins 28.9, parents not cousins 23.5 per 1,000). The difference in these proportions is but slight, and the relative number of cases of blindness attributed to each of the other causes is greater among those whose parents were not related.[77] [Footnote 77: U.S. Census, 1900, op. cit., p. 17.]