OCR Rendition - approximate

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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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