276 THE THEORY OF THE GENE 



of the sex-chromosomes, because only very rarely is there 

 indication of asymmetry of the accessory organs outside 

 the gonads, and the gonad tissue is frequently irregu- 

 larly distributed. Furthermore, if the evidence that the 

 sperm and eggs of hermaphrodites are both homogametic 

 is valid, the ground of a possible explanation due to chro- 

 mosome elimination is removed. 



From a hermaphrodite (Hh) Witschi was able to ob- 

 tain ripe sperm and eggs. He tested these with sperm 

 and eggs from a differentiated race with the following 

 results 



(1) Eggs dif. 9 by sperm from herm.= 5 5 



(2) Eggs herm. by sperm from dif. 5 = 50% $ -f 50% 5 



The eggs of the hermaphrodite were also fertilized by 

 sperm of the same individual and gave 45 9 and one her- 

 maphrodite, thus 



(3) Eggs herm. by sperm from herm.=45 5 -j-l herm. 



These results can be interpreted to mean that the original 

 hermaphroditic female was XX. Each ripe egg carried 

 one X. Likewise each functional sperm must also have 

 carried one X. There seems to be no escape from one or 

 the other conclusion, either that every sperm carries an 

 X, or else half carry X, half no X, but the latter die in the 

 female {i.e., never become functional).* 



4 Crew (1921) reports that he has succeeded in fertilizing eggs of a nor- 

 mal female -with sperm of an hermaphrodite. In each tadpole the develop- 

 ment of the gonad was direct. All the offspring (774) that were sufficiently 

 developed to determine the sex were female. The mother may be regarded as 

 a true XX female that produced eggs and sperm, each with an X-chromo- 

 some. 



Witschi (1928) has caused the transformation of the ovaries of all the 

 female tadpoles of Eana sylvatica into testes (with spermatogonia) by keep- 

 ing them at 32° C. after the seventh week. The males remained unchanged. 

 [Added 1928.] 



