78
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Parents cousins. | | | | |
--Totally blind | 1,291| 435 | 78 | 739 | 39
Parents cousins. | | | | |
--Partially blind | 1,236| 409 | 71 | 717 | 39
| | | | |
Parents not cousins.| | | | |
--The blind |53,980| 7,395 | 2,095 | 43,368 | 1,122
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Parents not cousins.| | | | |
--Totally blind |29,892| 3,720 | 1,090 | 24,541 | 541
Parents not cousins.| | | | |
--Partially blind |24,088| 3,675 | 1,005 | 18,827 | 581
| | | | |
Consanguinity not | | | | |
stated.--The blind | 8,256| 390 | 94 | 1,935 | 5,837
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Consanguinity not | | | | |
stated.--Totally | | | | |
blind | 4,462| 223 | 47 | 1,069 | 3,123
Consanguinity not | | | | |
stated.--Partially | | | | |
blind | 3,794| 167 | 47 | 866 | 2,714
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[A] Symbols for Blind Relatives--(a) blind brothers, sisters or
ancestors; (b) blind collateral relatives or descendants.

Of the 2527 blind persons whose parents were cousins, 993 or 39.3 per
cent have blind relatives, 33.4 per cent having blind brothers,
sisters or ancestors, and 3.9 per cent having blind collateral
relatives or descendants. And 9 per cent of the blind who have blind
relatives are of consanguineous parentage, while but 3.1 per cent of
the blind who have no blind relatives are the offspring of cousins.
These figures alone indicate a decided intensification of blindness
through consanguinity, although it should be remembered that a
relationship "works both ways," so that when a brother has a blind
sister, the sister would have a blind brother. This fact has probably
diminished the apparent number of sporadic cases of blindness.

Considered with reference to the degree of blindness the table shows
that 1291 or 51.1 per cent of