the blind of consanguineous parentage
are totally blind, and 1236 or 48.9 per cent are partially blind.
Among those whose parents were not cousins, 55.4 per cent were totally
and 44.6 per cent were partially blind.

Of the 2527 blind of consanguineous parentage, 632 or 25.0 per cent
were congenitally blind, of whom 350 or 55.4 per cent also had blind
relatives of the degrees specified. Not counting those who did not
answer the question in regard to blind relatives, we have 615 cases of
which 51.5 per cent had blind relatives of class (a), and 5.4 per cent
blind relatives of class (b). Taking the 53,980 blind whose parents
were not so related the number of congenitally blind was 3666 or but
6.8 per cent, of whom 1023 or 27.9 per cent had blind relatives.
Omitting as before the "blind relatives not stated," we have 23.4 per
cent who had blind relatives of class (a), and 4.3 per cent relatives
of class (b).

On the hypothesis that consanguinity in the parents intensifies a
tendency toward blindness we should expect to find among the
congenitally blind a larger proportion of consanguineous parentage
than among those blind from specific causes. In Table XXIII a general
classification of the causes of blindness is given together with the
consanguinity of parents. Specific causes in which the percentage of
consanguinity differs in a marked degree from the average, are given
parenthetically.

TABLE XXIII.
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| |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)