500 
Katharine Foot and E. C. StrobelJ 
As the formula is always the same in tlie zygotes as in the pa- 
rents, it is evident that in all snbsequent generations the spot will be ab- 
sent in all the females, and present in all the males, which is in accord 
whit the facts; but when we apply the same formnla to the cross between 
variolarius and servtis, the facts are clearly out of harniony with the theo- 
retical demands. 
As Goldschmidt's formula (Xo. 3) is the only oiie that works with 
pure variolarius, we must adopt it for the variolarius female used for the 
cross, thus: ^GGA'A' and as E. servus never has a spot on the male 
genital segment, the formula for servus must be G g A A, as follows ; 
$ variolarius 'S servus 
Soma GGA'A' GgAA 
Gametes G A' G A 
gA 
Zygotes G G A' A (no spot) G g A' A (spot). 
Kesults expected: All the males should have the spot. 
Facts: All the males do not have the spot (2 of the 11 Fi males have 
no spot whatever, and none of the remaining 9 have the spot as stroug 
as variolarius: it is present from a mere indication of a spot, to a spot 
about one third as strong as that of pure variolarius). 
Obviously, it will not help the Situation if we vary the formula for 
the male, and the formula for the female cannot be altered, for it is the 
only formula of Goldschmidt’s that will work for pure variolarius. 
It therefore seems cpiite clear that Goldschmidt’s formulae are ina- 
dequate as a theoretical explanation of the results of our cross-breeding 
experiments with Euschisius. 
In spite of persistent effort we have been unable to harmonize our 
results with any of the ingenious Scheines we have seen offered as theo- 
retical explanations of the transmission of characters that are inherited 
exclusively by one sex, or belong to the so-called sex-linked groups. 
IVe are considering two appearances, the genital spot of variolarius 
and absence of spot of servus, and each of these characters can be trans- 
mitted to the offspring. IVe have shown from the back cross p. 496, that 
one of these exclusively male characters (the genital spot) can be trans- 
mitted directly from the male and therefore through the so-called 
male producing Spermatozoon. Further, the off spring of this back 
cross show, not only the inheritance of the spot from the pure variolarius 
father but they also show the influence of the heterozygous (Fi) niother. 
