232 THE AMERICAN NATURALIST [Vol. LVI 



est. In most cases the decision was confirmed by several 

 subsequent experiments made for other purposes. Tiny 

 and square have not been definitely located with refer- 

 ence to forked since they proved unsuitable characters 

 for use in linkage experiments. Similarly, the loci of 

 triple and deformed are known to be between rough and 

 rimmed, but the relative positions of the two could not 

 be determined on account of the impossibility of using 

 the two characters together. Pale, morula, and rosette 

 are also only tentatively placed. 



With the order of the genes established, the "dis- 

 tances,'' or crossover values, between them were obtain- 

 ed by combining the data from all the experiments given 

 in Tables II-VI. Table VII gives the summary of all 

 data between any two loci in the *'map" from those ex- 

 periments in which no intermediate genes were concerned. 

 This differs from the usual method of summarizing the 

 data in that it includes only experiments in which no 

 intermediate point was used. 



