Page:Proceedings of the Royal Society of London Vol 60.djvu/306

280 1-0832,* while the ratios of 0'4374 to 0'4281 and 0-4488 to 0‘4427, are only 1-0219 and 1-0139 respectively, thus there is still a slight prepotency of paternal influence on stature to be recorded. (See § (4) (ii)-)

Confining onr attention to the differences in stature for fathers and sons corresponding to all m others whatsoever, we have, if be the difference in stature between father and corresponding fraternity of elder sons, D yfbetween father and fraternity of younger sons : Def = 0-5754-0-5719/*/. J)yf- 0-6208-0-5573/*/.

Hence the difference betwen the father and fraternity of younger sons will be greater than the difference between th e father and the corresponding fratern ity of elder sons unless the father be 3-110 inches less, or 1"059 more than the average. B ut 3'11 is about 1"2 and 1-059 about 0'415 times the standard deviation of the stature of fathers, or, fraternities of younger sons are nearer in stature to their father than fraternities of elder sons in about 46 per cent, of cases.

Sim ilarly if Dm, Dym represent the differences of stature of mothers and fraternities of elder and younger sons respectively, we have in inches Bern = 5-8416 -0-5626/*ra. B ym = 5-8870-0-5512/*M.

Thus fraternities of younger sons are always more divergent than fraternities of elder sons from the stature of th eir m others, unless the m other be 3-982 inches less, or 1053 inches more than the average. These are 1-6 and 4-24 tim es the standard deviation in stature of m others; or, only in about 5‘5 per cent, of cases are fraternities of younger sons nearer in stature to their m others than elder sons.

Now, it is difficult to read into these results any evidence for a steady telegonic influence. I t is true th a t the case of younger sons being more like their parents than elder sons occurs in eight times as many cases w ith the father as w ith the m other, but th e broad fact remains th a t in more than half the cases, judged by difference of stature, the elder son is more like the father than the younger son. In fact, examined in this way by difference of stature—not an unnatural manner of first approaching the problem—the true closeness of parent and offspring appears to be quite obscured by some secular, or, at any rate, periodic (see § 3) evolution in stature between successive generations—an evolution which even makes itself felt in the interval between younger and elder sons.

this fraction for the sexual ratio for stature.
 * 13/12 = 1"0833; thus these returns again confirm Mr. Gal ton’s selection of