18 SPOLIA ZEYLANICA. 
female is heterozygous for a sex factor not contained in the male, 
and that this sex factor may, on segregation of the gametes, repel 
the factor for some other character for which the female is also 
heterozygous. From the beautiful experiments of Doncaster and 
Rayner* it has been inferred that inheritance of this type occurs in 
the common currant moth (Abraxas grossulariata), where a distinct 
colour variety, var. lacticolor, occurs. The factor for the grossula- 
riata pattern appears to segregate against the female sex factor, 
with the consequence that in only one type of mating, and that a 
necessarily rare one, is the lacticolor pattern transmitted to the male 
sex.t Itis not difficult to conceive of an extension of these principles 
to cover cases of polymorphism among the females of a species, and 
the next few paragraphs are devoted to the consideration of an 
imaginary scheme of this nature. In the absence of experimental 
evidence such a scheme can of course have only a suggestive value, 
and I have ventured upon these speculations, after some hesitation, 
with the idea that they may attract the attention of some who have 
opportunities for breeding from species with polymorphic females. If 
any such are led to regard the problem from a rather different stand- 
point to that which has hitherto been customary, these speculations 
will not have failed of their purpose. 
Let us then suppose our imaginary case to be a species in which 
there are three distinct forms of female, «, 8, and y, of which the 
first (? «) is like the male. Let us suppose also that the forms 
@ and y have arisen from the original form @ by the elimination of 
factors through some mutational process, and that 6 and y are each 
heterozygous for a factor (A) for which ¥ « and the male are homo- 
zygous. Further, let it be assumed that the factor A segregates 
against the factor for femaleness in the way that the grossulariata 
factor behaves in the female of the currant moth (Abraxas). Lastly, 
let it be supposed that the difference between ¢ g and ? y depends 
upon the presence or absence of the factor B, which is not affected 
by the sex factor in segregation. Then we may represent the various 
individuals of our imaginary species as having one or other of the 
following zygotic constitutions :-— 
6 Fa 2 gy 
66 AA BB 6? AA BB 6? Aa BB 62 Aa bb 
or or or 
ég AA Bb 62 AA Bb 62 Aa Bb 
or or : 
66 AA bb 62 AA bb 

* Proc. Zool. Soc., 1906. 
+ In addition to the above instance this peculiar sex-limited form of inherit- 
ance has now been worked out in canaries and fowls. Inheritance of this 
form is certainly to be found in man also, while analogous phenomena have 
been met with in sweet peas. For a general account the reader may be referred 
to Bateson’s work on ‘‘ Mendels’ Principles of Heredity,’ Cambridge, 1909, 
chap. X. 
