62 



Comparison of Characters 



It remains, then, to determine whether or not forked and singed 

 in virilis and forked in funebris will fit into the above series. The 

 resemblance between the forked characters in the latter two species 

 has been noted under the description of forked (see also Sturtevant, 

 I.e.)- The resemblance is very close in nearly all respects, hence these 

 two may tentatively be classed as parallels. 



D.obscura 



D. melanogabter 



D. wiMi5toni 



singed 



- forked 



- stubby 



■ forked 



-smged 



■ stubby 



Figure 14. 

 X-chroraosome maps of three species of Drosophila, indicating loci of forked, singed, and stubby. 



We need to consider, therefore, only the singed and forked in 

 virilis in relation to the others. In doing this it is evident at the 

 outset that the most important criteria — sterility and egg modifica- 

 tions — can not be used. Fortunately, however, the two characters 

 are well marked (i. e., fairly extreme) and are different in several 

 respects. In singed the bristles are twisted and depressed, so that 

 they lie almost flat, especially on the thorax. The hairs are curled 

 and are also depressed. In forked the bristles and hairs are little 

 if any depressed, and are not noticeably curled. The bristles likewise 

 tend to be of the sharply forked rather than the curled type. 



None of these features is diagnostic, but they all tend to put 

 singed with the singed series. If a singed allelomorph with sterile 

 females were present in virilis the case would be much stronger, but 

 until some supporting or contradicting evidence is obtained the 

 above relationships may be considered as at least probable. 



This view receives considerable support from the relations of other 

 characters and the sequence of the loci on the map, as discussed 

 below. 



