Monoecism and Intersexuality 459 



Seller insisted that the development of these intersexes did not follow 

 the time law but was an intersexual development, that is, intermediate 

 between the sexes. Only for the gonads the time law was accepted 

 more or less reluctantly. But recently Seiler (1949, 1951) has con- 

 vinced himself that there is no such thing as intersexual development 

 but that differentiation is exclusively male or female for each cell or 

 group of cells or organ. In view of the existence of a graduated series 

 of intersexes, also in Solenobia, this new solution demands the ac- 

 ceptance of the time law. But Seiler still thinks that the facts do not 

 agree with this. His first objection is that there is a greater tendency 

 for a mosaic type of organization in the Solenobia intersexes than in 

 Lymantria: organs which are homologous in both sexes (i.e., based 

 upon an alternative norm of reaction of the same anlage ) do not show 

 a structure of the type described for Lymantria (and also Drosophila) 

 as a mosaic in time but an actual mosaic of female and male parts. 

 This is even now assumed for the gonads, though these show, just as in 

 Lymantria, only a tendency in one or the other of the eight compart- 

 ments not to undergo the intersexual change. The mosaic condition is 

 most conspicuous in the ducts developed from homologous anlagen. 

 We have already discussed the details in a different context, namely, 

 variegation (see 1 2 C d ee). For the present discussion the important 

 point is that in such organs the mosaic of low-grade intersexes means 

 the addition of small cell groups of the other sex; with increasing 

 intersexuality, these patches increase in number and size up to final 

 prevalence. When we discussed the proper embryological interpreta- 

 tion of this fact and compared it with the situation in Lymantria (see 

 I 2 C d ee), we saw that this is clearly a consequence of the working 

 of the time law in the presence of a definite type of embryonic deter- 

 mination. Seiler, however, proposes a very difiFerent explanation, which 

 to my way of thinking is very unfortunate: in the intersexes that he 

 himself had proved to be 3A 2X (no Y), he assumes that the F and M 

 factors are equally balanced and that the local environment decides 

 the alternative. Apart from the fact that such a view is genetically 

 unfounded and irreconcilable with all other knowledge on intersexu- 

 ality, it does not account for the graduated series of intersexuality. 

 The second point in the morphology of the Solenobia intersexes 

 is that, just as the gonad does, the products of the so-called Herold's 

 organ behave exactly as the time law requires, as Seiler's student 

 Nuesch has shown (detailed discussion in Goldschmidt, 1949). But 

 Seiler regards this as less important than the fact that sexual charac- 

 ters which are developed from different anlagen may both be present 



