CHAPTER XXVII 



THE INTERNAL FACTORS OF SEX DETERMINATION (Continued) 

 The Origin oj Gynandromorphs 



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 \vorker 



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