Internal Factors of Sex Determination 409 
other kind resulting from the united nuclei. The former should 
produce only male parts, because this is what happens when the 
egg is not fertilized; the latter should produce female parts, 
as does a fertilized egg. In other words, the results in the differ- 
ent parts of the single, imperfectly fertilized egg are the same as 
those formed in unfertilized and fertilized eggs. 
I have pointed out that the results are capable of being equally 
well explained in another way. It has frequently been noted 
that two spermatozoa occasionally enter the egg of the bee. If 
we suppose one of these only conjugates with the female nucleus, 
its products should produce female parts, while the other sperm 
nucleus that fails to conjugate will, if it divides and produces 
nuclei, give rise to male parts. Boveri’s view and my own are 
not mutually exclusive: either process may at times take place 
and produce gynandromorphs. Ihave pointed out how it might 
be possible under certain conditions to determine whether the one 
or the other process has taken place. In a case like that de- 
scribed by von Siebold, in which the mother belongs to one race 
and the father to another, the parts of the embryo that contain 
the single nucleus should be like the mother on Boveri’s view, 
and like the father on my own; in both, the parts supplied by 
the conjugated nuclei produce a hybrid result. An example 
may make this clearer. Let us suppose, as in von Siebold’s 
case, that the queen is Italian and the male a German drone. 
If one spermatozoén enters the egg and conjugates with one 
of the first two segmentation nuclei, as on Boveri’s view, the 
male parts of the embryo that come from the single segmentation 
nucleus must be like the mother, z.e. they should have the char- 
acter of the Italian bees; the parts that come from the conjugat- 
ing nuclei should be hybrid. On my view two spermatozoa enter 
the egg, one only conjugating with the egg nucleus. The male 
parts will come from the single sperm nucleus, and will, there- 
fore, be like the father, z.e. they will have the character of the 
German bees; the parts that come from the conjugating nuclei 
will be hybrid in character. Thus on my view the male parts of 
the gynandromorphous hybrid will be paternal; on Boveri’s 
