1210 } REPORT—1883. 
parentage and the zero value of the ancestry. Its combination with the mid- 
parental deviate will be as if, not pure water, but a mixture of wine and water in 
some definite proportion had been poured into the wine. The process throughout 
is one of proportionate dilutions, and therefore the joint effect of all of them is to 
weaken the original wine in a constant ratio. 
We have no word to express the form of that ideal and composite progenitor, 
whom the offspring of similar mid-parentages most nearly resemble, and from 
whose stature their own respective heights diverge evenly, above and below. He, 
she, or it, may be styled the ‘generant’ of the group, I shall shortly explain 
what my notion of a generant is, but for the moment it is sufficient to show that 
the parents are not.identical with the generant of their own offspring. 
The average regression of the offspring to a constant fraction of their respective 
mid-parental deviations, which was first observed in the diameters of seeds, and 
then confirmed by observations on human stature, is now shown to be a perfectly 
reasonable law which might have been deductively foreseen. It is of so simple a 
character that I haye made an arrangement with one movable pulley and two 
fixed ones by which the probable average height of the children of known parents 
can be mechanically reckoned. This law tells heavily against the full hereditary 
transmission of any rare and yaluable gift, as only a few of many children would 
resemble their mid-parentage. The more exceptional the gift, the more exceptional 
will be the good fortune of a parent who has a son who equals, and still more if he 
has a son who overpasses him. The law is even-handed; it levies the same heavy 
succession-tax on the transmission of badness as well as of goodness. If it dis- 
courages the extravagant expectations of gifted parents that their children will 
inherit all their powers, it no less discountenances extravagant fears that they will 
inherit all their weaknesses and diseases. 
The converse of this law is very far from being its numerical opposite. Because 
the most probable deviate of the son is only two-thirds that of his mid-parentage, 
it does not in the least follow that the most probable deviate of the mid-parentage is 
8, or 1} that of the son. Thenumber of individuals ina population who differ little 
from mediocrity is so preponderant that it is more frequently the case that an ex- 
ceptional man is the somewhat exceptional son of rather mediocre parents, than 
the average son of very exceptional parents. It appears from the very same table 
of observations by which the value of the filial regression was determined, when it 
is read in a different way, namely, in yertical columns instead of in horizontal lines, 
that the most probable mid-parentage of a man is one that deviates only one-third 
as much as the man does. ‘here is a great difference between this value of 3 and 
the numerical converse mentioned above of 3; it is four and a half times smaller, 
since 4}, or 3, being multiplied into 4, is equal to 3. 
Let it not be supposed for a moment that these figures invalidate the general 
doctrine that the children of a gifted pair are much more likely to be gifted than 
the children of a mediocre pair. What it asserts is that the ablest child of one 
gifted pair is not likely to be as gifted as the ablest of all the children of very 
many mediocre pairs. Howeyer, as, notwithstanding this explanation, some sus- 
picion may remain of a paradox lurking in these strongly contrasted results, I 
will explain the form in which the table of data was drawn up, and give an 
anecdote connected with it. Its outline was constructed by ruling a sheet into 
squares, and writing a series of heights in inches, such as 60 and under 61,61 and 
under 62, &c., along its top, and another similar series down its side. The former 
referred to the height of offspring, the latter to that of mid-parentages. Hach square 
in the table was formed by the intersection of a vertical column with a horizontal 
one, and in each square was inserted the number of children out of the 930 who 
were of the height indicated by the heading of the vertical column, and who 
at the same time were born of mid-parentages of the height indicated at the side 
of the horizontal column. I take an entry out of the table as an example. In 
the square where the vertical column headed 1 69- is intersected by the horizontal 
1 A matter of detailis here ignored which has nothing to do with the main 
principle, and would only serve to perplex if I described it. ; 
———— NT eer. ee eee 
