THE THEORY OF SEX 603 



point occurs. For a further check we beg to compare an organ 

 as figured in figure 44 with the pictures which Meisenheimer'' 

 gives of male copulatory organs, developed after extirpation of 

 Herold's organ (from which penis and valvae derive). They 

 are identical, the explanation being that in our case development 

 was female and no Herold's organ was formed up to such a late 

 point that no time for its development was left; but the rest of 

 the development was purely male. 



The importance of this set of facts makes it desirable to illus- 

 trate them further with an other organ, leaving the complete 

 description of all details for a later monographic account. The 

 most interesting organ is, of course, the sex-gland. We have 

 shown in our former publications that, in the case of female 

 intersexuality, the ovary remains up to the highest grade of in- 

 tersexuality but becomes more and more rudimentary^ or, rather, 

 embryonic. And only in the highest types of female intersexu- 

 ality is the ovary finally transformed into a testis. This fact 

 agrees very well with the theory, since it is known that the sex- 

 glands in moths are perfectl}^ differentiated in very young cater- 

 pillars. If, therefore, the beginning of the male development 

 does not occur at a ver\^ early^ stage, the ovary persists, merely 

 stopping growth and remaining embryonic. But if this turning- 

 point arrives at a time in development when the stage of ovarian 

 differentiation still permits a dedifferentiation, the ovary may 

 still be transformed into a testis. We could indeed show, that 

 in crosses which yield the latest stage of female intersexuality; 

 young caterpillars are found with normal ovaries, whereas the 

 adult moths show every stage of the transformation of an em- 

 bryonic ovary into a testis. (The small variations, which are 

 always found in the time of the turning-point have, of course, 

 the result that, when development ends, some glands are com- 

 pletely transformed while others are not changed.) 



^ Meisenheimer, J. Experimentelle Studien zur Soma-und Geschlechts- 

 differenzierung. Jena, 1909. Fig. 11, p. 21. 



'' Woltereck, R. Ueber Veraenderung der Sexualitaet bei Daphniden. In- 

 ternat. Ztschr. Hydrol)iol. 4, 1911. P\irther in ^'el•handlg. deutsclio Zool. Gcs. 

 1911. 



