i 9 n] SHULL REVERSIBLE SEX-MUTANTS 365 



from the genetic hermaphrodites, but when used as pollen parents 

 they produce no hermaphrodite offspring, but only females and 

 normal males. 



The fact that males can be modified so as to produce functional 

 organs of both sexes, indicates that they are sex heterozygotes, 

 and the production of both females and hermaphrodites by self- 

 fertilized hermaphrodites strongly supports the same interpretation. 



The hermaphrodite character can neither find expression in 

 the females, nor can it be transmitted by their eggs to the male 

 offspring. Consequently it is not determined by an independent 

 gene, H, but by a modification of the male sex gene, M, or of the 

 "synaptic mate" of the female gene, F. 



If the males and hermaphrodites are heterozygous, it follows 

 that the females are homozygous; but this does not offer an ulti- 

 mate solution to the relationship between females and males, 

 since there may be several different kinds of homozygotes and 

 heterozygotes. As applied to the relation of the sexes, these may 

 be indicated by the following formulae: (a) The female may be a 

 " positive " homozygote; then FF= ?, Ff= $, *Ff H or FH= $. (b) If 

 the female is a " negative" homozygote, FFmm = $, FFMm=$, 

 FFM H m=$. (c) When the female is a "neutral" homozygote, 

 FF=$, FM=$, FM H =$. In each of these formulae the subscript 

 H is intended to represent a modification of the gene to whose 

 symbol it is appended, such that the male is changed to a her- 

 maphrodite. Which of these formulae correctly represents the con- 

 dition in Lychnis can not be determined, but the modified gene 

 which results in hermaphroditism is allelomorphic to F unless 

 the female is a negative homozygote. 



Among the offspring of genetic hermaphrodites were a small 

 number of male mutants (n in 5467), which on breeding proved 

 to be normal males. The occurrence of these male mutants indi- 

 cates that the modification to the hermaphrodite condition, and 

 back again to the male condition, occurs with but slightly unequal 

 facility, and this circumstance is believed to favor the view that 

 mutation in this case depends upon reversible modifications of 

 some permanent element or organ, rather than upon the origina- 

 tion of a new unit, and its disappearance. This interpretation 



