General Introduction. 



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Fig. 1. — Types of Drosophila chromosome groups. (From Metz, 19166). All but type H 

 are found in the genus Drosophila. H is from Cladochaeta nebulosa Coq. 



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D.funebris D willistoni o D. obscura cC 



Fig. 2. — Chromosome groups of species of Drosophila which are being studied genetically. 



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