696 General arid Applied Biology 



B 



C A 



D D 



C A 



B D 



B 



Fig. 342. — Diagram showing the crossing ov^er of genes from one homologous 

 chromosome to the other during synapsis. Observe the exchange of the genes A-C 

 and B-D. Crossing over may occur at more than one point in much the same 

 raianner as shown. (From Potter: Textbook of Zoology, The C. V. Mosby Co.) 



I(X) 



KY) 



-■XELLOW BODY 

 -WHITE EYE 

 -RUBY EYE 



— rCOT WING 

 — TAN BODY 



--DUSKY WINO 

 --SABLE BODY 



SMALL WING 



-CLEFT WINO 

 __ BOBBED HAIR 

 --MALE FERTILITY t 



i ^LONG BRISTLES t 



M 



'^-- ROUGHOID EYE 



--A-MALE FERTILITY T 



/--STAR BYE 

 ./-■-GULL WINO 

 "STREAK BODY 



-/—JAMMED WING 



-BLACK BODY 

 -PURPLE EYE 



-V — VESTIGIAL WING 

 A — FRINGED WING 



-LETHAL 

 --SPECK BODY 



-DIVERGENT WING 



-SEPIA EYE 

 /—HAIRY BODY 



SCARLET EYE 

 -MAROON EYE 



^\-i- SPINELESS HAIR 



\- -EBONY BODY 

 A--WHITE OCELLI 



-\ — ROUGH EYE 

 -CLARET EYE 



BENT WING 

 7 EYELESS 



:^-7 MINUTE HAIRS 



Fig. 343. — Chromosome map of the fruit fiy (Drosophila sp.), showing the 

 locations (loci) of some of the genes in the autosomes (11, III, IV) and in the sex 

 chromosomes {I, X) and (/, Y). The name applied to the gene is given to the 

 right of its locus, and the distances between them are approximate. 



