No. 642] VARIATION IN SEX CHARACTERS 61 



intersexes correspond to the presence of three or of two 

 fourth-chromosomes respectively. 



There is another connection in which the wide fluctua- 

 tions of the intersexes are interesting, namely, the action 



of environmental factors. The slight range <>f tliu-ni 

 tion in such a character as miniature-wings in Di n><,j,]ii 

 probably means that there is a critical bahuice or rat 

 of plus to minus modifiers beyond which all bahuuM 

 give miniature, at least until the overbalance proceeds \ 

 far that a new critical ratio is passed and a new supe 

 miniature character is realized. Tlie l)al;ni(*e iii mini 

 ture is so far beyond the critical balance that ouIn raiv 

 are the environmental factors strong eiiouuh i<» (•ntwfii. 

 this overbalance and thus cause fhietnnt k'h. In inut.m 

 in which the overbalanee is slight tln-rr ^^ill 1m' hnlh ^^H 

 fluctuation due to ( ii\ i roiniicntal iiitrrt.'ifii''*' .iim .i h- 

 susceptibility to modi licat ion 1)\ ot hfi- ,u»'iu a- n 

 toriouslv the case with r.caihMl ;ni<l with I niiu-;itf. 



In normal males an<l fmiah'S ihnv aiv luuh o^vv\M 

 ances bevond the eritieal p<.ints, and eoii>r<iuentl> oii 

 slight genetical or fluctuating variations. 15ut in the i 



