BLASTOGENIC VARIATIONS. 15$ 



little more in detail than we did in the last chapter, and 

 it will then be obvious that a character becomes more 

 and more fixed in the offspring, the more and more fully 

 it is represented in the parents, grandparents, and more 

 remote ancestors. Thus, according to the law, offspring 

 receive a half of their heritage from their parents, a 

 quarter from their grandparents, and so forth. But of 

 what is this half and this quarter made up ? Obviously 

 half of the parental half heritage, or a quarter in all, 

 was received from their parents, and a quarter of a half, 

 or an eighth in all, from their grandparents, and so on; 

 whilst, as regards the quarter heritage received by the 

 offspring from their grandparents, a half of it, or an 

 eighth in all, was received from their parents, and so 

 on. By tracing back the heritages in this way, it is 

 therefore possible to calculate the absolute amounts of 

 any character or strain present in offspring, as distin- 

 guished from the relative amounts; relative, that is, to 

 those present in the parents and other ancestors. For 

 instance, supposing the parents and parents only had 

 been selected in respect of any particular character, the 

 condition of the previous ancestors being entirely un- 

 known, then, as we have already seen, the offspring will 

 exhibit these exceptional characters in only .6 of their 

 full strength, or will have regressed to this extent to- 

 wards the general mean of the race. Supposing the 

 grandparents have been selected in respect of the same 

 characters, as well as the parents, then Pearson * has 

 calculated that the offspring will exhibit the characters 

 in .8049 of their full strength; if the great-grand- 

 parents also, then in .9027 of their strength; and if still 

 *Proc. Roy. Soc., Ixii, p. 39! 



