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THE AMERICAN NATURALIST [Vol. XLII1 



a few external organs added to the normal set the causes 

 may lie in conditions not found till late, after fertilization. 



Just as the determination of sex may be due to dif- 

 ferent conditions in various animals and plants, so the 

 repression or the expression of one or another sex organ 

 may be due to diverse causes acting at various periods 

 of ontogeny, and not to any single factor. Moreover, we 

 do not know how far the gynandromorph may be the 

 result of aberrations independent of the causes of deter- 

 mination of the gonads. 



However amongst the insects, where gynandromorphs 

 are well known, there are reasons for restricting our 

 surmises as to the time of origin of the mixed expression 

 of sex organs. Here the mixing seems to be associated 

 with the period of fertilization. In the honey bee the 

 sex is determined, apparently, in fertilization and the 

 phenomenal cases of gynandromorphs, such as those 

 studied by V. Siebold in 1863, in the Eugster hive, have 

 often been explained as due to abnormal fertilizations. 

 This interpretation has been most acutely elaborated by 

 T. H. Morgan on the basis of the facts of experiments 

 upon echinoderms and the results of Toyama upon 

 hybrid moths. He is finally led to the view 3 that the 

 egg nucleus by itself would produce male, the sperm 

 nucleus by itself also male, but the two combined produce 

 female. The gynandromorph would be the result of 

 polyspermy. It would be a sort of combination of indi- 

 viduals, the one female, arising from the part of the egg 

 containing the fused egg and sperm nucleus; the other, 

 male, arising from the part of the egg in which extra 

 sperms developed without contact with the egg nucleus. 

 The female parts of the gynandromorph would have two 

 parents and should be mixed in a hybrid, the male parts 

 would have but one parent and should be pure in a hybrid. 



The hypothesis of polyspermic origin of gynandro- 

 morphs might be applied to the crayfish with the common 

 assumption of two sorts of sperm, male producing and 



3 This journal, November, 1907. 



