INTRODUCTORY. 



21 



The sex-linked factors of Drosophila. 



Gen. 



White 



Rudimentary 

 Miniature. . . 

 Vermilion. . . 



Yellow 



Abnormal . . . 



Eosin 



Bifid 



Reduplicated 



Lethal 1 



Lethal la*. . . 



Spot* 



Sable* 



Dot* 



Bow* 



Lemon* 



Lethal 2 



Cherry 



Fused* 



Forked* 



Shifted* 



Lethal sa. . . . 



Bar 



Notch 



Depressed* . . 

 Lethal sb. . . . 



Club* 



Green* 



Chrome* .... 



Lethal 3 



Lethal 3a. . . . 

 Lethal li*... 



Facet* 



Lethal sc . . . . 

 Lethal sd. . . . 

 Furrowed. . . . 



Part affected. 



Eye-color. . . 



Wings 



Wings 



Eye-color. . . 

 Body-color. 

 Abdomen. . . 

 Eye-color. . . 



Wings 



Legs 



Life 



Life 



Body-color. 

 Body-color . 



Thorax 



Wings 



Body-color . 



Life 



Eye-color. . . 

 Venation . . . 

 Bristles. . . . 

 Venation . . . 



Life 



Eye-shape. . 



Wing 



Wing 



Life 



Wings 



Body-color. . 

 Body-color. . 



Life 



Life 



Life 



Eye 



Life 



Life 



Eye 



Figure 



II 

 A 



7-8 



lO 



5 



4 



7-8 



B 



14-17 



2 



C 



3 



9 

 D 



E 

 F 



12-13 



H 



Symbol. 



r 

 m 



V 



y 



A' 



we 



bi 



h 



ha 



ys 

 s 



Im 



•2 

 WC 



fu 



f 



Sh 

 Isa 



B' 



N' 

 dp 



isb 

 Cf 



I3 



I16 



fa 



Isc 



Isd 

 fw 



^ocus. 



I . I 



55-1 

 36.1 

 33.0 



0.0 



2.4 



I . 



6. 



34- 

 o. 



3. 

 o. 



43- 

 33 



I 



■3 

 ■7 

 ■7 

 ■3 

 .0 

 .0 



175 

 12.5 = 



I . I 



59-5 

 56. 5 

 17.8 

 23.7 

 57. o 

 2.6 

 18.0 

 16.7 

 14.6 



26.5 



195 

 I 



2.2 



66.2 



I — 



38. 



Found by. 



Morgan. 



Morgan. 



Morgan. 



Morgan. 



Wallace. 



Morgan. 



Morgan. 



Morgan. 



Hoge. 



Rawls. 



Rawls. 



Cattell. 



Bridges. 



Bridges. 



Bridges. 



Wallace. 



Morgan. 



Safir. 



Bridges. 



Bridges. 



Bridges. 



Stark. 



Tice. 



Dexter. 



Bridges. 



Stark. 



Morgan. 



Bridges. 



Bridges. 



Morgan. 



Morgan 



Morgan. 



Bridges. 



Stark. 



Stark. 



Duncan. 



the zero, with white at i, and with bifid at 6. If we know the cross- 

 over values given by a new mutant with any two mutants of the same 

 chromosome whose positions are already determined, then we can 

 locate the new factor with accuracy, and be able to predict the cross- 

 over value which the new factor will give with any other factor whose 

 position is plotted. 



The factors are located preferably by short distances (i. e., by those 

 cases in which the amount of crossing-over is small), because when the 

 amount of crossing-over is large a correction must be made for double 

 crossing-over, and the correction can be best found through breaking up 

 the long distances into short ones, by using intermediate pomts. 



Conversely, when a long distance is indicated on the chromosome 

 diagram, the actual cross-over value found by experiment (;. e., the 



