218 



T. H. MORGAN AND SABRA COLBY TICK. 



TABLE III. 



FROM STRAP cf X WILD 9 . 



are worthy of inspection. The ratios run more evenly and range 

 from I : 2.3 to i : 7.7 with one exceptionally high at I : 13.5. 

 The counts from day to day (not recorded here) show that the 2 

 strap-winged flies hatch later than the flies with normal w r ings, 

 so that as the cultures run out, the relative number of strap- 

 wing flies increases, and unless the cultures are exhausted when 

 the count stops there will be a deficiency of strap-wing flies. 

 An attempt was made to run the cultures to a finish, although 

 this cannot always be done. If the cultures dry up, a dispro- 

 portionately large number of strap-winged flies will be destroyed, 

 and this will account in part for the deficiency in this class. 

 These results are not affected by the age of the parents, as 

 shown by comparison of the ratios in the totals for the second 

 (i : 3.75) and third (i : 3.12) broods with that of the first 



The above pairs were mated in November and December, 1913. 

 In order to make a more exact comparison, a few mass cultures 

 were made in December from the same stocks. The results are 

 shown in the next table (IV.). 



In addition to the preceding data there were other crosses of 

 strap male by wild female that had been made nine months 



