342 



Morgan. 



Females. 



CRlIXCRmX = Red Lon^ 

 cRMXCRmX = ,, 

 CRmXCRmX = Red Rud 

 cRmXCRmX = ,, 

 crMXCRmX = Red Long 

 CrMXCRmX = ,, 

 crmXCRmX = Red Rud 

 CrmXCRmX = ,, ,, 



Males. 



CRMXcrm = Red Long 

 cRMXcrm = White Long 

 CRmXcrm = Red Rud. 

 cRmXcrm = White Rud. 

 crlMXcrm = White Min. 

 CrMXcrm = Red Min. 

 crmXcrm = White Rud.- min. 

 CrmXcrm = Red ,, 



The miniature white males (500) are to the miniature red males 

 (254) as 2 to I. The rudimentary red males (249) are to the rudi- 

 mentary white males (93) as 2.7 to i. The statements made for the 

 preceding case in connection with the relation between C and R, etc., 

 hold here also. In both cases the discrepancy in the ratio in the 

 miniature red to white and rudimentary red to white would seem to 

 be due to relative viability. 



The Infertility of Rudimentary Winged Flies. 



Tlie following facts challenge attention : 



1. No offspring were produced when rudimentary females were 

 mated to rudimentary males, although several hundred matings were 

 made. 



2. But rudimentary males fertilized readily long winged females. 



3. And rudimentary females may be fertilized by normal males, 

 but with difficulty. Only long winged females are produced, with 

 rarely a rudimentary winged male, as 300 : i. 



It is evident that the failure in the first case to obtain any 

 offspring cannot be due to total lack of fertility on the part of either 

 sex, but must depend on some condition relating to the union of like 

 to like gametes. 



Another fact of significance should be added to the foregoing: — 

 When the heterozygous females, that are produced by the union of 



