Deaf in the Twelfth Census of the United States.[75] This report was prepared under th

By this method he obtained verified returns of 64,763 cases of blindness in continental United States or 85.2 per 100,000 of the total population.

ny of his relatives blind? If yes, what relatives? (Father, mother, grandparents, brothers, sisters, uncles, aunts, and how many of each, so far as known)." The results of this inquiry give us the best and

the 57,726 who answered the question in regard to blind relatives, 10,967 or 19 per cent replied in the affirmative.[76] The blind relatives were divided into two groups

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latives Class (a).[A] Having blind relatives Cla

763 8,629 2,3

5,645 4,378 1,2

29,118 4,251 1

--The blind 2,52

-Totally blind 1,

-Partially blind

-The blind 53,980 7,3

-Totally blind 29,892

Partially blind 24,088

ated.--The blind 8,2

ted.--Totally blind 4

ted.--Partially blind

nd brothers, sisters or ancestors; (b) b

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 consangui

lind of consanguineous parentage are totally blind, and 1236 or 48.9 per cent are partially blind. Among

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

ion of consanguineous parentage than among those blind from specific causes. In Table XXIII a general classification of the causes of blindness is given together

E XX

otal. Consanguinity o

Not stated Cousins N

527 53,980 8,25

33,930 1,000 28,797

cornea 11,380 444 10

451 73 1,267 1

,165 71 1,026

iris 1,307 33 1,09

lens 11,769 228 9,46

,474 235 8,221 1,

ffected 7,944 276 6

885 938 12,463 1

,728 632 3,666 4

10,157 306 8,797

313 5,740 1,95

from th

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, pa

e greatest proportion is

e somewhat increased. Allowing for these the same proportion as for those who did answer the question we should have of all the blind 4.47 per cent as the offspring

rsity of Iowa examined the 181 blind children in the Iowa College for the Blind, and found th

etc., and consider only those who suffered because of congenital conditions, we should find that 14 per cent were the result of cons

hree years before the publi

odying in all 621 cases, of which 167 or 27 per cent were the offspring of consanguineous parents.[79] Retinitis pigmentosa is perhaps more generally attributed to consanguineous marriage than any other specific

general population 852 per million are reported as blind, and 63 per million as congenitally blind. The actual figures for the offspring of cousin marriages are 2527 per million for all blind and 632 per million for the congenitally so. In other words only 0.25 per cent of the offspring of cousin marriages are blind and only 0.05 per cent are congenitally blind. Although the probability that a child

distinct investigations.[81] In this table the percentages of deaf-mute offspring of consanguineous marriage to the total number of deaf-mutes investigated, varies from 30 per cent to none at all. Of

riage problem extending over the period of six successive censal years. Although we can hardly suppose that these figures are accurate in all respects, they throw a great deal of light

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l population Cong

on Average number to a

. Average numbe

78 4,127 628 --

4,096 706 1.2

3,503 647 1.3

3,163 611 1.3

2,570 546 1.4

2,179 489 1.4

om Tab

nsanguineous Marriage and De

are two possible explanations for this phenomenon, both of which may have operated in part; first that in the great emigration the deaf-mutes have been left behind, and second that with the introduction of improved methods of census taking, the returns are more

y in Table XXIV varies less than any other part of the table, and clearly shows a much higher average number of deaf children where the parents were cousins. They reveal the interesting fact that the occurrence of two or more deafmutes in a family is more than twice as probable where the parents are related as where they are not. Table X

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al Deaf mutes to a

amilies in which d

5. 6. 7. 8

ins 127 45 20 10

sins 91 38 24 5

ins 63 30 13 6 1

sins 82 38 19 9

sins 79 34 23 7

A] 2963 347 158 35

A] 2460 305 167 47

A] 2080 281 162 39

[A] 1473 273 134

A] 1219 231 122 34

d Dumb" to a family, "as f

1871 fourth cousins produced more deaf-mutes per marriage than any nearer relationship. In 1881 third cousins produced more than any nearer relationship."[83] Mr. Huth forgets that he is basing these statements on five and nine families respectively, and does not take into consideration the probability that if the returns are biased, as he suspects, this bias would affect the more distantly related,

percentage is fairly typical of each set of returns we may say that from three to six per cent of the Irish deaf-mutes are the offspring of first cousin marriages. If, then,

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Parents. 1871 1

Number of marriages Number of conginital deaf-mutes Average per marriag

128 1.78 74 123

0 89 1.78 29 46

4 40 1.67 9 21

s 5 11 2.20 1

usins 12 19 1.58 n

1.76 113 191 1

2 3,609 1.27 2,474 3,22

896 1.30 2,587 3,420

e Tabl

hat of 544 deaf-mutes, 28 were the offspring of 24 consanguineous marriages.[85] There were 504 families represen

monize with that of the marriage of cousins. The district of Saeterdalen has the greatest number of consanguineous marriages (201 out of 1250), but not a single case of deaf-mutism. Hedemarken, which has the fewest consanguineous marriages has a great many deaf-mutes

age of 20 per cent as of consanguineous origin. Four investigations give the number of children to a fam

E XX

r of Children

ineous marriages.

sh Census

mi 1.7

d 1.5

ann 1.

e that statistics of the deaf have been very poor until recent years. Not

. Alexander Graham Bell. An enumeration of Dr. Bell's services directly, and through the agency of the Volta Bureau, in this cause, cannot be given here.

latives. It is unfortunate that in these returns it is impossible to distinguish between degrees of relationship, but in such an extensive compilation it was doubtless impracticable to

d (d) relatives. These groups are: (a), deaf brothers, sisters or ancestors; (b), deaf uncles, aunts, cousins or other relatives not (a), (c) or (d); (c), deaf child

s which number more than 3000 cases. The extreme variation in the percentages of those who are the offspring of consanguineous marriages cannot be attributed to mere chance. There is clearly some fundamental connection between consanguinity and congenital deafness if 11.8 per cent of all the congenitally deaf are the offspring of consanguineous marriages,

E XX

otal. Consanguinity

Not Stated. Cousins. N

065 75,530 9,69

ernal ear 871 29

ear 34,801 1,238 30,8

al ear 12,295 343 11

05 2,183 25,281 3

272 7,544 2,2

,424 285 6,647

4,210 222 3,683

304 10,450 94

81 2,666 327

91 83 3,741 16

38 2,369 954

3,242 40 2,897

1,710 11,322 1,4

atives. In Table XXIX the close connection between deaf relatives of these groups and consanguinity is shown. For the sake of simplicity no account is taken of (c) relatives (deaf children), and (d) relatives (deaf h

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[A] Total. Consanguinit

Not Stated. Cousins. N

065 75,530 9,69

,911 73,639 2,9

6 154 1,891 6,7

,660 1,850 18,83

8,821 2,061 54,801

s 25,851 2,171 22,5

ves 4,117 412 3,58

ives 17,543 1,438 15

tives 4,191 321 3,7

ves 54,630 1,740 51,

eaf brothers, sisters and ancestors;

, for few people are well enough informed in regard to their ancestry to answer this question definitely. Not one man in thousands can even name all of his great-grandparents, to say nothing of describing their physical or mental traits. Others may have understood the inquiry to refer only to living relatives and therefore have omitted almost all reference to their ancestors. These possible errors might easily explain all the excess of the percentage of consanguinity among those reported as having no deaf relatives over the probable percentage of consanguineous marriage in the general population. But this very probability that comparatively few deaf ancestors have been reported increases the probability that the greater part of the (a) relatives were b

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[A] Total. Consanguinit

Not Stated. Cousins. N

710 11,322 1,44

1,647 11,110 6

044 63 212 76

,295 986 3,961

a) relatives 860 126

elatives 7,273 535 6

others, sisters or ancestors; (b) deaf uncl

14.6 per cent were the offspring of cousins, while of those having (a) relatives 18.6 per cent were the offspring of consanguineous unions. Thus it would seem to be a more reasonable conclusion that where two or more deaf-mutes appear in the same family, at least a tendency toward deaf-mutism is hereditary in the family and is intensified by the marriage of cousins, rather than that consanguineous marriage is in itself a cause. The fact that in many cases the relationship would "work both ways" would

ered the inquiry as to deaf relatives, it will be seen (Table XXXI) that while of all the deaf less than one third are returned as having d

still more striking. Table XXXII shows that 66.5 per cent of the congenital

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s. Total. Consanguinit

sins Total Cous

ed 80,481 3,911 73,

,660 1,850 18,83

58,821 2,061 54,8

es 25,851 2,171 22

tives 4,117 412

tives 17,543 1,438

latives 4,191 321

ives 54,630 1,740 5

ers or ancestors; (b) deaf uncles, aunts, cousins,

E XX

s. Total. Consanguinit

sins Total Cous

ed 13,428 1,647 11,

5,295 986 3,96

) relatives 860 1

relatives 7,273 535

ers, sisters or ancestors; (b) deaf uncles

eous parentage as among the offspring of unrelated parents. This is not inconsistent with the Irish returns which show the

relatives, 437 or 1.4 per cent reported deaf children and 30,897 or 98.6 per cent reported no deaf children. Of the totally deaf 2.4 per cent had deaf children, and

E XX

ives. Percentage ha

f. Partially deaf.

r (d) 1.4

2 3.3

1.1 1.4

d) 6.3 6.

o (a) 2.2

o (d) 1.4

(d) 0.9

nd (d) 9.5

t no (b) 5.5

t no (a) 2.5

(a) or (b) 2

t no (d) 1.9

(b) or (d) 1

(a) or (d) 1

or (d) 0.9

t given where base

ancestors; (b) deaf uncles, aunts, co

the 242 persons who have (a), (b) and (d) relatives, 23 or 9.5 per cent also have (c) relatives. A consanguineous marriage within a family tainted with

iage in ten as productive of deaf offspring. The total number of children of these marriages was 6,782, of which 588 were deaf. These 3,078 marriages represented 5,199 deaf married persons as compared with the 31,334 reported in the Twelfth Census, or about one sixth. Increasing the 300 families who had deaf children in the same ratio we have 1800 as compared with the 437 r

consanguineous marriages of the deaf are larger. The following table which combines several of Dr. Fay's tables sets forth the main results of his wo

E XX

. Number of marriages Marriages resu

Number Number De

ins 7 4 57

sins 5 3 6

sins 1 1

14 3 21.

aunt 1 1

elated 3 2

uineous 31 14

r no information 3,04

3,078 300 10

have reached by other means, namely that where a tendency toward deafness exists, a consanguineous marriage is more likely to produce deaf children than a non-consanguineous marriage. If more figures were

g plural deaf offspring, than ordinary marriages, and two thirds of the congenitally deaf offspring of consanguineous marriages do have deaf relatives, it doe

is not removed by the elimination of the congenitally deaf. Many instances are known where successive generations in the same family have developed deafness in adult life, often at about the same age and from no apparent cause. The following case well illustrates this point. It is furni

the parents of healthy children. A-- was troubled with deafness as long as I can remember, and this physical trait he transmitted to all of his children, though some of the

isappeared entirely in the next generation with a non-consanguineous marriage. The inheritance of tendencies or w

fness is produced. We are not all built like that wonderful one-horse shay that was so perfectly made in all its parts that when at last it broke down it crumbled into dust. When an accident

deed the true cause at all. It may be the cause simply in the same sense that the pulling of a trigger is the cause of the expulsion

to look for a cause of the defect in consanguinity itself? When two explanations are possible, the simpler explanation is the more probable, other factors being equal; but in the present prob

a great majority of the deaf in the United States. The 89,287 deaf would mean an average of 12 deaf persons to every 10,000 inhabitants and the 14,472 congenitally deaf, 2 persons to every 10,000. Assuming then, as before[93] that 1,000,000 persons in continental United States are the offspring of consanguineous marriages within the limits of the

by Dr. Bell in 1891, as to the probable results o

latives, will probably not increase his liability t

atives, will probably increase his liability to

d relative, especially if that relative should happen to be on the deaf side of the family. For example: If his father has deaf relatives and his

iage in such a family would probably be beneficial, by increasing and intensifying these desirable characteristics in the offspring. On the other hand, if a large proportion of the members of a family betray weakness of constitution-for example: if many of the children die in infancy, and a large proportion of th

account of deafness, but on account of the danger of weakening the constitution of the offspring. Remoteness of blood is eminently favorable to the production of vigorous offs

tend to revert to the common type of the race. Deafness and other defects would be most likely to disappear from a family by marriage with a person of different nationality.