CHAPTER XXVII 
THE INTERNAL FACTORS OF SEX DETERMINATION (Continued) 
The Origin of Gynandromor phs 
THERE are occasionally found, especially in certain groups of 
insects, individuals that have the characters of the male on one 
side of the body and of the female on the other. Such cases 
occur most often in bees, ants, and butterflies; and since in the 
first, at least, it has been shown that the female sex is determined 
by fertilization, and the male by the lack of fertilization, it seems 
probable that when both sexes appear in the same individual 
that this may be brought into connection with the fertilization. 
These mixed sexual individuals are known as gynandromorphs. 
The most celebrated case of this sort is that of the Eugster hive 
of honey bees, studied by von Siebold. Similar instances had 
been seen before, but von Siebold studied the forms more thor- 
oughly, and brought his results into connection with Dzierzon’s 
theory in regard to sex determination in bees. 
The hive in which these gynandromorphous bees occurred 
contained an Italian queen bee and German drones. The 
workers that were produced were therefore hybrids. It is not 
known whether the hybrid character of the workers had any- 
thing to do with the frequent occurrence of gynandromorphism 
amongst them. Purely bred colonies have also produced these 
abnormal forms. The gynandromorphs showed the male 
characters sometimes on the right side of the body and the fe- 
male characters on the left, or vice versa; sometimes the ante- 
rior end was male and the posterior female. Sometimes the 
male and female character occurred in different parts of the 
same organ, as in an eye or in an antenna. The normal worker 
407 . 
