INHERITANCE OF ABNORMAL VENATION. 15 
THE DATA CONCERNING INHERITANCE. 
Without reference to the grandparents, the data are summarized in 
table 7: 
TABLE 7. 
Average 
p. ct. of 
abnormal 
offspring. 
Crosses. 
INormalisenormialatescsscocsscccoseosnces 9.6 
Abnormal male X normal female... 35.8 
Normal male X abnormal female... 54.7 
Abnormal <apnormal c.:-ccs«cssssseess 85.9 
In this work a fly is counted as abnormal if there is the slightest trace 
of abnormality in either wing. These results leave no room for doubt 
concerning the heritability of the tendency toward extra veins. 
Tables 8 to 19 show the relation between various ancestors and the 
offspring. The coefficients of association found from these are given 
below the respective tables. Although these coefficients are greater 
than expectation on the basis of Pearson’s Law of Ancestral Heredity, 
they do not negative his conclusions. He was very careful to exclude 
cases in which there is inbreeding or assortative mating. Both were 
largely practiced in these experiments. These coefficients do show, how- 
ever, that change of sex in the ancestry does not uniformly weaken in- 
heritance. Thus, the average coefficient of association between father 
and sons, and mothers and daughters (no change of sex) is 0.78; and 
that between father and daughters, mothers and sons (one change of 
TABLE 9. 
SONS. DAUGHTERS. 
ied ae ag 
3011 1329 4340 
951 2763 3714 
C. A.=0.694. 
TABLE 10. 
SONS. 
pi oer Pea 
N.} 2801 465 
A. 1389 2820 
C. A.=0.819, 
MOTHER. 
M 
Sec 
Cc. A.=0.786. 
TABLE 11, 
DAUGHTERS. 
TR ae 
[aie [se [a 
C. A.=0.864. 
MOTHER 
