CHROMOSOME I 



The Cellular Basis 



CHROMOSOME II CHROMOSOME III 



195 



CHROMOSOME IV 



FIG. 67. MAPS OF THE FOUR CHROMOSOMES OF Drosophila melanogaster 

 showing positions of a few of the nearly 400 mutant genes ; those that have 

 been most accurately located are marked with a star. (From information 

 furnished by Morgan and Bridges.) Figures of several of these Droso- 

 phila Mutuals will be found on pp. 286-288. 



