THE CAUSE OF GYNANDROMORPHISM IN INSECTS 



T. H. :morgax. 



In recent years many cases have been recorded in the ojroup of 

 insects in which parts of the body show the characters of the male 

 and other parts those of the female. Most frequently the separa- 

 tion lies along the middle line of the body, so that one side is like 

 the male and the other like the female. About two years ago I 

 attempted in the case of the bee to correlate this result with the 

 well known frequency of dispermy of the insects' egg.^ Two 

 spermatozoa having entered, one fuses with the egg nucleus and 

 its products produce the female characters; the other develops 

 alone and gives the characters of the male to the parts of the body- 

 it supplies with nuclei, etc. 



That the latter assumption is not arbitrary is shown by experi- 

 ments with thv eg<r of the sea-urchin in which it has been possible 

 to fertilize a, non-nucleattvl ])ivvv of the eu'u' with a single sperma- 

 tozoon. Hoveri lias attenij)te(l to proxc (hat under these condi- 

 tions the characters of the larvae aiv paiernal, wliieli is in accord 

 with our hypothesis for the hee. The evidtMiee h()\v(>vt>r on which 

 Boveri's conclusion rests has be(Mi dispnled. More nucntlv ( lod- 

 lewski has succeeded in cross-lVrtili/.inu- a n..n-nn<-leatc<l tVau'nient 

 of tiie egg of a sea-urchin with the sperm of a crinoid. The char- 

 acters of the yonnt;- hirvac are said id be maternal, indicating that 

 the protophisin I'ather than the nncleiis is the controlling factor 



<.nl> to th.- verv tarlicM Mauc of development, ^\here accor!l!,i- 

 to i)rieMl,\ n-ult. the maternal imluence. piedominate. 



A tc.t of tlu- xieu that I haxe .nuu<'.te.l ^l.onM lu- found for the 



nuclei shonld be female and hybrid in cliaract(>r. while those that 

 come from the single nucleus of the spermatozoon should be male 



ItiirriMctiition of the Origin of CJynandro- 



