Chap. XII. GENERAL RESULTS. 465 



as 100 to 78 in height, and as 100 to 51 in fertility ; 

 and plants of Eschscholtzia similarly compared were 

 as 100 to 45 in fertility. In comparison with self- 

 fertilised plants the results are still more striking ; 

 thus cabbages derived from a cross with a fresh stock 

 were to the self-fertilised as 100 to 22 in weight. 



Florists may learn from the four cases which have 

 been fully described, that they have the power of fixing 

 each fleeting variety of colour, if they will fertilise the 

 flowers of the desired kind with their own pollen for 

 half-a-dozen generations, and grow the seedlings under 

 the same conditions. But a cross with any other in- 

 dividual of the same variety must be carefully pre- 

 vented, as each has its own peculiar constitution. After 

 a dozen generations of self-fertilisation, it is probable 

 that the new variety would remain constant even if 

 grown under somewhat different conditions ; and there 

 would no longer be any necessity to guard against inter- 

 crosses between the individuals of the same variety. 



With respect to mankind, my son George has en- 

 deavoured to discover by a statistical investigation * 

 whether the marriages of first cousins are at all in- 

 jurious, although this is a degree of relationship 

 which would not be objected to in our domestic 

 animals ; and he has come to the conclusion from his 

 own researches and those of Dr. Mitchell that the 

 evidence as to any evil thus caused is conflicting, but 

 on the whole points to its being very small. From the 

 facts given in this volume we may infer that with 

 mankind the marriages of nearly related persons, some 

 of whose parents and ancestors had lived under very 

 different conditions, would be much less injurious than 

 that of persons who had always lived in the same 



* 'Journal of Statistical Soc' June 1875, p. 153; and * Fortnightly 

 Review,' June 1875. 



2 H 



