METHODS FOR TESTING LINKAGE 



79 



distances are recombinations and which are the result of subtractions. The linear order 

 of many of the genes is subject to some degree of uncertainty. Those indicated by 

 symbols in italics have not been critically tested to determine their position relative to 

 all other genes in the linkage group. The order of the other loci is established with a 

 fairly high probability of correctness. Many experiments disagree in the estimate of 

 recombination obtained. In combining estimates from different experiments the usual 

 procedure has been to weight the recombination fraction by the amount of information 

 in the body of data contributing the estimate. In linkage groups VI and XIII, how- 

 ever, where there are striking differences in amount of recombination between the 

 sexes, weighted averages for each sex separately were calculated, and the unweighted 

 average of the sexes was taken. There are differences between the sexes in other regions 

 of the linkage map also, but the differences are either small enough or the estimates 

 from the two sexes well enough balanced, so that the unweighted method of averaging 

 would have made very little difference. In general when sex differences occur recom- 

 bination is higher in females than in males, but in linkage group VI and between sh-2 

 and wa-2 in linkage group VII the reverse is true. 



Following is a list of the names of the genes used in the map. The numerous 

 alleles at the histocompatibility loci and at the t locus have not been listed. For the 

 other multiple allelic series, the mutants which have been given names are listed. 

 The references cited all give information on linkage, with the exception of a few, cited 

 for members of a multiple allelic series, which contain the original description of the 

 allele. Where no reference is cited, a description has been given by Griineberg. 507 



Symbol for 

 Gene 



Name of Gene 



References 



p-sterile 



425. 493, 498, 500, 518. 1112, 1244, 1267, 1466 

 594 



