364 BOTANICAL GAZETTE [NOVEMBER 



is conceivable that the alternative sexual types may be determined 

 in different cases by very different methods, some qualitative, 

 some quantitative, and others both qualitative and quantitative. 

 In some species the sexes appear to represent a much more strongly 

 polarized ( ?) condition than in other species, and a transition from 

 the characters of the one sex to those of the other is attained 

 only with the greatest rarity, if at all ; while in other species the 

 sex conditions may be so nearly balanced or neutral that individuals 

 are not so absolutely determined in their sex relations by their 

 genotypic nature, thus resulting in ever-sporting varieties in 

 respect to sex, such as CORRENS (7) has found in Plantago lanceo- 

 lata. 



With such a conception of sex, it also appears probable that 

 sex may be influenced sometimes by external factors as well as 

 by internal ones, and in this case the preponderance of one sex 

 over the other, which has been observed in many animals and 

 plants, need not be attributed alone to a selective disorganization 

 of germ cells, a selective fertilization, or a selective death rate, 

 but might conceivably be controlled to a certain extent by environ- 

 mental conditions acting at some particular " sensitive period" 

 in the ontogeny of the organism in question. However this may 

 be, there is little or no evidence at present that such environmental 

 influences on sex can be more than relatively slight in the case of 

 dioecious plants and animals. In such organisms recent genetic 

 and cytological studies prove conclusively that sex is generally 

 determined by the genotypic nature of the individual. 



Summary 



'The hermaphrodites of Lychnis dioica are modified males. 

 They are of two kinds, which are here distinguished as " gene tic" 

 and " somatic" hermaphrodites. 



When the genetic hermaphrodites are used as pollen parents, 

 either when self -fertilized or in crosses with females, their prog- 

 enies consist of females and hermaphrodites. When they are used 

 as pistil parents, and fertilized by normal males, they produce 

 females and normal males. 



Somatic hermaphrodites may be externally indistinguishable 



