CASTLE: THE HEREDITY OF SEX. Ze 
furnished by the recessive parent. If gametes of opposite sex always 
unite in fertilization, and the sex-character borne by the hybrid gamete 
always dominates, the resulting zygotes will be D (R) g:and RQ. 
See Table IV. But if dominance attaches to the gametes of one 
parent as often as to those of the other, the result will be D(R) g + 
D(R)2P+RG4+ RQ. Manifestly neither of these results agrees 
closely with the one observed, which hes between the two. It seems 
probable, then, that if coupling does occur, it occurs not in all possible 
cases, but only in a part of them. 
TABLE IV. 
Sex-distribution among offspring of Aglia tau (R) crossed with its aberration 
lugens (D). Compare Table ITI. 
3 P Calculated Calculated 
1.95 Sex of .| distribution, distribution 
ae gles eo Total R. | Offspring.| coupling in all [coupling in 4 of 
$s iS Nature of 2 3 ee cases. 
8 3 Cross. = Sof A 3 3 DB) 
ar S pga lsoled lp os 19 
Ey reseed Seals 
TEN oes | Rea aa Reeser 
‘Mae DX Ek ? Vall D 0|02 
EV... (1 ])D, (CR) X<CR 86; 1:1] 438/42] 45 |41/45 
IV.,[2]|D(R) X D(R)| 86} 8:1 |21.5)81] 44 | 42/44/42 
IV.,[38]|D(R) XR 75|' 1:1 |87.5|38} 39 | 386/39 
V., [4] |D(R) X D (R)| 102} 3:1 | 25.5) 11) 52 | 50) 52/50 
Wi, | (5) “A 87| 8:1 |21.7/10| 49 | 38/49/38 
Note. Numerals in italics indicating the observed distribution are, for conve- 
nience in comparison, inserted immediately below the calculated numbers. 
Suppose that it occurs in only one-third of them; then the gametes 
of the hybrid will be 2D ¢@+D9+R4+42R2. If such gametes 
meet others all of which are R, as in a cross with a recessive individual, 
and if sexual dominance is possessed in all cases by the gamete of the hybrid 
parent, we get the following distribution of zygotes, 2 D(R) ¢ + D 
(R)? +R G+2RK Q, which, as we have seen, is close to that ob- 
served. Compare Table IV., Generation IV. [1] and [3]. On the other 
hand, the assumption that sexual dominance is possessed as often by 
the gamete of one parent as the other would lead to the result normal 
