208 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
the normal disparity between the sexes is naturally accentuated. Never- 
theless, the differences between calculated and observed ratios are small 
in all the crosses except [6] and [7]. Even in these two cases calculated 
and observed results are qualitatively harmonious. Both indicate a 
large excess of males; but the observed excess is larger than the 
expected one, especially in cross [7]. 
2. CouPLING OF CERTAIN SEX AND SOMATIC CHARACTERS IN THE 
GERM-CELLS. 
In certain other crosses among Lepidoptera, males and females occur 
in their normal proportions, approximate equality, but there is a ten- 
dency for the offspring which resemble one parent to be predominantly 
of one sex, those which resemble the other parent being predominantly 
of the other sex. In the following crosses between a species and its 
melanistic aberration, Standfuss (96) notes the predominance of males 
among the offspring having the aberrant form, while females predomi- 
nate among those which have the species form. 
Offspring like Offspring like 
aberration. species. 
dS 4 d S 
Psilura monacha)x< ab.zatima . . .  .0- > 18 5 2 20 
Alia tau b> Cab. Iugens.. 2 4s 2 ss 186 | 113 43 89 
Grammesia trigrammica X ab.bilinea . . . 14 14 13 20 
Angerona prunaria X ab.sordiata . .. . 24 18 3 10 
Boarmia repandata X ab.conversaria . . . 4 2 10 18 
In these cases, there is clearly an imperfect correlation between the male 
sex-character and the aberrant form-character. Is such correlation con- 
sistent with the doctrine of gametic differentiation? It is; correlation, 
or “coupling,” between members of different pairs of characters is a 
recognized Mendelian phenomenon. Thus, Correns (:00) has shown that 
in crossing Mathiola incana with M. glabra, those hybrid plants which 
have villous leaves always bear pink flowers, and those which have 
glabrous leaves bear white flowers. Leaf character and flower color are 
in this case perfectly correlated, or ‘‘ coupled,” so that they cannot be sepa- 
rated in heredity. Similarly, though less perfectly, in the butterfly crosses 
