No. 610] LINKAGE IN LYCOPEESICUM 



615 



by 1.73, the figures given in column 3 of Table III are ob- 

 tained. The figures in this column represent the number 

 of plants which presumably should have been obtained 

 in the four different categories, if the expected number of 

 dwarf plants had been obtained. 



These corrected numbers can then be compared with 

 the closest theoretical ratio where the gametes, instead 

 of being produced in the equal proportion of 1 AB : 1 Ab : 

 1 aB : 1 ab, were produced in unequal proportions (where 

 A and B represent the two dominant factors— standard 

 vine and non-constricted fruit). In this case if the 

 gametes were formed in the proportion of 1 AB:4 Ab: 

 4 aB : 1 ab, the agreement between the corrected result 

 and the theoretical expectation is surprisingly close. 



It is seen that the data obtained by Hedrick and Booth 

 give a clear indication of linkage of the factor for stand- 

 ard vine with that for constricted fruit and dwarf vine 

 with non-constricted fruit. Frequent breaks in the linkage 

 occur to form the two new combinations. On the chromo- 

 some hypothesis the data show, in this case, that crossing 

 over occurs in 20 per cent, of the gametes formed. 



TABLE IV 



Habit of Vine and Color of Fruit— Characters which 













AB.... 

 aB ' 



Standard vine, red fruit 



Standard vine, yellow fruit 



Dwarf vine, red fruit. 



Dwarf vine, yellow fruit 



TotaT.~77.".T.'. 







