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96

Life and Letters of Francis Galton

there will be a great bias in the returns owing to the limited number of gametic constitution* in the sires. The following table gives the results as

Table of Colour Inheritance in Horses.

 
 

No. of

Observations

Colour

of Dam

Colour

of Sire

Percentages of Colour in Offspring

Chestnut

Bay

Brown

Black

A (i)

68

Chestnut

Chestnut

100

 

-

-

(ii)

1900

Bay

Bay

10

81

6

3

(iii)

19

Brown

Brown

-

42

52

5

(iv)

25

Black

Black

-

4

28

68

B

407

Chestnut

Bay

33

61

4

2

 

366

Bay

Chestnut

30

63

3

 

C

52

Chestnut

Brown

-

86

11

2

 

69

Brown

Chestnut

16

65

10

9

 

7 2

Chestnut

Black

6

76

15

3

 

57

Black

Chestnut

30

40

 

30

E

221

Bay

Brown

1

79

14

6

 

450

Brown

Bay

6

66

18

10

F

156

Bay

Black

3

60

30

7

 

268

Black

Bay

7

53

16

24

G

5.5

Brown

Black,

-

22

38

40

 

6

Black

Brown

-

16

50

33

Percentages taken only to whole numbers.


published by Galton. In the first line of the series of rows, A (i), we see that for 68 cases of chestnut mated with chestnut all the offspring were chestnut. Galton does not comment on this, but it . was the source of considerable later controversy. A certain number of matings of chestnut with chestnut taken from Wetherby's Thoroughbred Studbook gave the same result as the first row of Galton's matings; but a longer series, wherein it was pointed out that the Studbook did contain some instances of chestnut mated with chestnut not producing chestnut, was rejected on the ground that these instances must be due to error of record, a most circular process of reasoning.

It is clear from B where we are dealing with a fairly adequate number of crossings both ways that (i) there is not a predominance of sire or dam for chestnut with bay matings, and (ii) bay may contain a factor of chestnut. If we work out from B the number of bays with a factor for chestnut we find them to be 31.5 °/0, while 68.5 °/o lack that factor. Applying these percentages to the 1900 bay and bay matings in A (ii) we should


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