462 Genetics of Sex Determination 



definite external conditions, for example, position of sex cells in gonads, 

 age Qf the individual, metal ions (BoncUia), hormone-like secretion 

 (proboscis secretion in BonelUa, etc.); and (3) any one of the pos- 

 sible variants that can influence the genie action of F and M. The 

 sooner the term "phenogenetic sex determination" disappears from 

 genetic literature, together with the superfluous A and G factors, the 

 better for the clarity of our understanding. 



The correctness of the conclusion can be illustrated by the realiza- 

 tion that all imaginable conditions of transition exist within the phe- 

 nomenon of monoecism or hermaphroditism, which is the genetic basis 

 of Hartmann's group of phenotypic sex determination. Let us take a 

 monoecious plant, that is, a plant in which F/M is in sufficient balance 

 to make the plant as a whole a hermaphrodite. However, within the 

 flower anlage the local internal conditions (probably of genically con- 

 trolled hormonic type) are such that the inner circle of anlagen pro- 

 duces only gynoecia; the outer one, androecia. In another such her- 

 maphrodite, only a few of the outer circle anlagen produce androecia; 

 the rest, staminodia. Again, in another hermaphrodite the internal 

 environment (hormone titer?) in some flowers is such that the outer 

 circle anlagen are more or less suppressed in their differentiation, while 

 in other flowers it is the inner circle which is suppressed. Now we 

 know genetic monoecists in which comparable suppressions are pro- 

 duced by modifiers, that is, by the genetic environment, or under the 

 influence of a definite plasmon, or by the interaction of modifiers and 

 plasmon (as discussed in the foregoing chapter). Finally, the sex of 

 the anlagen can be shifted independent of their position when such 

 modifying genetic conditions produce intersexuality superimposed 

 upon monoecism. Where does phenotypic sex determination belong 

 in this series? Why is a modification of genie action by, say, a hormonic 

 titer or another gradient and the same efifect by the action of a genetic 

 modifier, possibly by way of the same chemical channel, different in 

 principle? The only clear-cut difference is between genetic monoecism, 

 that is, F = M, and genetic dioecism by development of the 2X-1X 

 mechanism, that is, MM F(X) or MM F(X) F(X). However, even 

 here transitional conditions are found. 



The same argument applies to animals. There are true hermaphro- 

 dites which we can understand only as based upon a F/M balance, 

 where F = M. The differentiation of the male and female apparatus 

 is a problem of embryonic differentiation through diversification of 

 areas, just like any other differentiation. Thus we would have to 

 speak of two types of phenotypic sex determination within the same 



