eyed. "In a word, the grandfather transmits his charact- 

 ers visibily to half of his grandsons but to none of his grand- 

 daughters." (Morgan). 



In the second case the characters appear in the females 

 and are transmitted by the males. That is, if a lacticolor 

 (Abraxas) female mates with a grossulariata male the pro- 

 geny are all grossulariata, but if these are inbred the male 

 progeny are grossulariata and half the females lacticolor. 

 "The lacticolor grandmother has transmitted her peculiarity 

 visibly to half of her grand-daughters but to none of her 

 sons" (Morgan), 



Laboratory Exercises with Drosophila 



The Drosophila fly is one of the most convenient 

 organisms to employ with classes in demonstrating the na- 

 ture of Mendelian inheritance. It can be readily secured 

 about fermenting fruit, and can be reared in large numbers 

 in sterilized vials containing bits of fermenting bananas. 



Ni:^/ 



Fig. 20. — Drosophila ampelophila. a. female and 

 b, male (After Morgan.). 



Precaution must be taken however, to prevent bacterial and 

 fungal infection of the bananas. Mutants will usually be 

 found where a large number of the flies are bred. The nor- 

 mal fly has a grayish-yellow body, long wings and red eyes, 

 but forms may be discovered having black, yellow or 

 ebony bodies; miniature or vestigial wings; and white or 

 sepia eyes. (Fig. 20). 



120 



