152 



OTTO L. MOH« 



the total offspring of all the femak's tested are taken together we get 

 877 granddaughters, 566 non-singed and 218 singed grandsons of the 

 mosaic. 



The test presented in Table 3 shows moreover, that the new 

 mutation is not allelomorphic to forked, since all the daughters had 

 normal wild-type bristles. The fact that singed sons appeared among 

 the offspring demonstrates that some of the females fertilized were 



TABLE 2. Pi; /;/ pr cii $$ >< Sk cii ^, exception. Fi; 7i bl pr cu ÇÇ 

 ex 2702 X Sk cu ^^, (mass culture). 



TABLE 3. Pi; bl pr cu $2 X Sk cu ^, exception. 16 Fi Sk cu $? X 

 W^ i> f <^<^', mass culture. (In the classification the Sk character is 



disregarded). 



heterozygous for the new mutant gene. If this gene were allelomor- 

 phic to forked we would therefore have obtained some daughters that 

 show a bristle alteration, since the fathers used in this cross were 

 forked. 



V. THE SOMATIC MUTATION AN ALLELOMORPH 

 OF SINGED, (Singed'). 



It has been mentioned above that two previously known sex- 

 linked récessives, viz., singed (at 20,9) and an allelomorph of forked, 

 called forked* (at 56,5) both produce bristle and hair alterations stri- 

 kingly similar to those produced by the new mutant gene here descri- 

 bed. When it had been demonstrated through the test just mentioned, 

 that the new mutation was not allelomorphic to forked, there was 

 every reason to believe, that we were dealing with a reappearance 



